[Federal Register: January 9, 2004 (Volume 69, Number 6)]
[Rules and Regulations]
[Page 1619-1641]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr09ja04-20]
[[Page 1619]]
-----------------------------------------------------------------------
Part II
Department of Transportation
-----------------------------------------------------------------------
Federal Aviation Administration
-----------------------------------------------------------------------
14 CFR Parts 1, 91, et al.
Enhanced Flight Vision Systems; Final Rule
[[Page 1620]]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Parts 1, 91, 121, 125, and 135
[Docket No. FAA-2003-14449; Amendment Nos. 1-52; 91-281; 121-303; 125-
45; 135-93]
RIN 2120-AH78
Enhanced Flight Vision Systems
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The FAA is revising its regulations for landing under
instrument flight rules to allow aircraft to operate below certain
specified altitudes during instrument approach procedures, even when
the airport environment is not visible using natural vision, if the
pilot uses certain FAA-certified enhanced flight vision systems. This
action informs the public and the aviation industry of the approval of
the use of new technology for certain operational benefits.
DATE: Effective February 9, 2004.
FOR FURTHER INFORMATION CONTACT: Les Smith, Flight Technologies and
Procedures Division, Flight Standards Service, AFS-400, Federal
Aviation Administration, 800 Independence Ave. SW., Washington, DC
20591; telephone: (202) 385-4586.
SUPPLEMENTARY INFORMATION:
Availability of Rulemaking Documents
You can get an electronic copy of this document using the Internet
by:
(1) Searching the Department of Transportation's electronic Docket
Management System (DMS) Web page (http://dms.dot.gov); do a Simple
Search for ``14449.''
(2) Visiting the Office of Rulemaking's Web page at http://www.faa.gov/avr/arm/index.htm
or
(3) Accessing the Government Printing Office's Web page at http://www.access.gpo.gov/su_docs/aces/aces140.html
.
You can also get a copy by submitting a request to the Federal
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence
Avenue, SW., Washington, DC 20591, or by calling (202) 267-9680. Be
sure to identify docket number FAA-2003-14449, or the title of this
final rule, ``Enhanced Flight Vision Systems.''
Anyone is able to search the electronic form of all comments
received into any of our dockets by the name of the individual
submitting the comment (or signing the comment, if submitted on behalf
of an association, business, labor union, etc.). You may review DOT's
complete Privacy Act statement in the Federal Register published on
April 11, 2000 (Volume 65, Number 70, pages 19477-78) or you may visit
http://dms.dot.gov.
Small Business Regulatory Enforcement Fairness Act
The Small Business Regulatory Enforcement Fairness Act (SBREFA) of
1996 requires the FAA to comply with small entity requests for
information or advice about compliance with statutes and regulations
within its jurisdiction. Therefore, any small entity that has a
question regarding this document may contact its local FAA official, or
the Office of Rulemaking at (202) 267-8487. You can find out more about
SBREFA on the Internet at http://www.faa.gov/avr/arm/sbrefa.htm, or by
e-mailing us at 9-AWA-SBREFA@faa.gov.
List of Abbreviations Used in This Document
AC--Advisory circular
AGL--Above ground level
ASR--Airport surveillance radar
AWO--All-weather operations
DH--Decision height
EFV--Enhanced flight visibility
EFVS--Enhanced flight vision system
EVS--Enhanced vision system
FPV--Flight path vector
FSB--Flight Standardization Board
HAT--Height above touchdown
HUD--Head-up display
IFR--Instrument flight rules
ILS--Instrument landing system
JAA--Joint Aviation Authorities
MDA-Minimum descent altitude
PAR--Precision approach radar
RNAV--Area navigation
SAE--Society of Automotive Engineers
SVS--Synthetic vision system
TAOARC--Terminal Area Operations Aviation Rulemaking Committee
TERPS--U.S. Standard for Terminal Instrument Procedures
TSO--Technical Standard Order
VOR--Very high frequency omnirange station
VDP--Visual descent point
Outline of Preamble
I. Background
II. Discussion of the Proposed Rule
III. Related Rulemaking Actions
IV. Discussion of Comments
IV.1. General
IV.2. Flight visibility and visual references
IV.3. Visual cues (visual references)
IV.4. Restricted visual references
IV.5. Harmonization
IV.6. Airport lighting systems
IV.7. Electromagnetic spectrum
IV.8. Limitations of systems
IV.9. Other technologies
IV.10. Regulatory Bar To Use of Systems Such as SVS
IV.11. Differentiation between runway and taxiway
IV.12. Obstacle clearance
IV.13. Weather-related comments
IV.14. Equipment-related weather minimums
IV.15. Operational intent of the rule
IV.16. Operational benefits for part 121, part 125, and part 135
operations
IV.17. Part 121, part 135, and part 129 operations
IV.18. Operational experience before credit for lower minimums
IV.19. Takeoff minimums for EFVS
IV.20. Rule should be an advisory circular (AC)
IV.21. Terminology: Category I and Advisory Circulars
IV.22. Coordination through TAOARC and AWO process
IV.23. EFVS flight path performance
IV.24. Inconsistency with terminology in AC 120.28D or AC
120.29A
IV.25. EFVS use for Category II and Category III approaches
IV.26. Compliance with Sec. 91.1039
IV.27. Definitions--Italicization and capitalization
IV.28. Definitions--Scope of enhanced flight vision systems
IV.29. Definitions--Examples of enhanced flight vision systems
IV.30. Definitions--Enhanced flight vision systems
IV.31. Definitions--Topography and enhanced flight vision
systems
IV.32. Synthetic vision systems
IV.33. Enhanced ground visibility systems
IV.34. Straight-in approaches
IV.35. Flight visibility or enhanced flight visibility
IV.36. Reduced approach minima
IV.37. Natural vision
IV.38. AC 120-29A
IV.39. Reduced environment as a visual reference
IV.40. Barometric altitude
IV.41. Reliance on EFVS
IV.42. Touchdown zone determination
IV.43. Training
IV.43.a. AFS and RFM limitations
IV.43.b. No additional training
IV.43.c. Additional training and proficiency
IV.43.d. Crew training
IV.44. Requirements for the Airplane Flight Manual (AFM)
IV.45. Air carrier operations specifications requirements
IV.46. Foreign aircraft certification
IV.47. Equipment requirements for subpart C
IV.48. Clarification on maneuvering
IV.49. Certification of an EFVS
IV.50. Performance-based advisory materials
IV.51. Display comments
IV.51.a. Head-up or head-down displays
IV.51.b. Head-up display
IV.51.c. Guidance, flight path vector (FPV) and other symbology
IV.51.d. EFVS for situational awareness
IV.51.e. Design eye position
IV.51.f. Display conformality and parallax errors
[[Page 1621]]
IV.51.g. Power system for an EFVS
IV.51.h. Independent displays
IV.52. Comments on economic evaluation
V. Contact with Aircraft Manufacturer for Confirmation of
Performance Capabilities
VI. Differences Between the NPRM and Final Rule
VII. Discussion of Final Rule
VIII. Paperwork Reduction Act
IX. International Compatibility
X. Economic Evaluation
XI. Regulatory Flexibility Determination
XII. International Trade Impact Analysis
XIII. Unfunded Mandates Assessment
XIV. Executive Order 13132, Federalism
XV. Environmental Analysis
XVI. Energy Impact
I. Background
Section 91.175 of 14 CFR contains the flight visibility
requirements for conducting operations to civil airports using natural
vision to identify the approach lights and runway environment. These
instrument approach requirements have been modified over the years to
provide for operating an aircraft during reduced visibility conditions
while maintaining a high level of safety. The current rules on
instrument approach procedures do not allow aircraft to operate below
the decision height (DH) or minimum descent altitude (MDA) if the
airport environment cannot be seen with natural vision. This final rule
allows operators conducting other than Category II or Category III
straight-in instrument approach procedures to operate below the DH and
MDA when new technologies, such as an enhanced flight vision system
(EFVS), use imaging-sensor technology that provides a real-time image
of the external topography. During some reduced visibility conditions,
an EFVS can display imagery that may significantly improve the pilot's
capability to detect objects, such as approach lights and visual
references of the runway environment that may not be visible. This
final rule will allow, but not mandate, the use of this kind of
technology.
II. Discussion of the Proposed Rule
By notice of proposed rulemaking (NPRM) Notice No. 03-03, February
10, 2003 (68 FR 6801), the FAA proposed to amend its rules to allow for
the operational use of an EFVS, which can display imagery that may
significantly improve the pilot's capability to detect objects that may
not otherwise be visible. The FAA proposed that the provisions of this
NPRM would apply to operations conducted under parts 91, 121, 125, 129,
and 135. The comment period on the proposal closed March 27, 2003.
In the NPRM, the FAA also proposed that the pilot of an aircraft
could use this system to determine ``enhanced flight visibility'' while
flying a straight-in standard instrument approach procedure. An EFVS
would enable the pilot to determine ``enhanced flight visibility'' at
the decision height (DH) or MDA, in lieu of ``flight visibility'' (as
currently defined), by using a head-up display (HUD) to display sensor
imagery of the approach lights or other visual references for the
runway environment at a distance no less than the visibility prescribed
in the instrument approach procedure being used.
The FAA proposed to define ``enhanced flight visibility'' as the
average forward horizontal distance, from the cockpit of an aircraft in
flight, at which prominent topographical objects may be clearly
distinguished and identified by day or night by a pilot using an EFVS.
This definition would be substantially equivalent to the definition of
flight visibility in part 1. The pilot would use this enhanced flight
visibility and go through a similar decisionmaking process as required
by existing Sec. 91.175 (c) to continue the approach from the DH or
MDA down to 100 feet above the touchdown zone elevation of the runway
of intended landing. At that point and below, certain things would have
to be visible to the pilot without using the EFVS in order for the
aircraft to proceed to a landing on the intended runway. This rule will
permit but will not require the use of this technology.
The proposed rule, therefore, could allow for operational benefits,
reduced costs, and increased safety for aircraft equipped with an EFVS.
Use of an EFVS with a HUD may improve the level of safety by improving
position awareness, providing visual cues to maintain a stabilized
approach, and minimizing missed approach situations. In addition to
using an EFVS to satisfy new Sec. 91.175 (l) requirements, an EFVS may
allow the pilot to observe an obstruction on the runway, such as an
aircraft or vehicle, earlier in the approach, and observe potential
runway incursions during ground operations in reduced visibility
conditions. Even in situations where the pilot experiences the required
flight visibility at the DH or MDA, he or she could still use an EFVS
to have better situational awareness than may be possible without it
especially in marginal visibility conditions.
However, it should be noted that the NPRM did not propose to allow
the use of a ``synthetic vision'' system as a means of determining the
required enhanced flight visibility or to identify one of the visual
references for the intended runway. Synthetic vision is a computer-
generated image of the external scene topography from the perspective
of the flight deck that is derived from aircraft attitude, a high-
precision navigation solution, and a database of terrain, obstacles,
and relevant cultural features. A synthetic vision system is an
electronic means used to display a synthetic vision image of the
external scene topography to the flight crew.
III. Related Rulemaking Actions
In a separate rulemaking project, the FAA conducted a thorough
review of its rules to ensure consistency between the operating rules
of 14 CFR and future proposed area navigation (RNAV) operations for the
National Airspace System (NAS). On December 17, 2002, the FAA published
a proposed rule entitled, ``Area Navigation (RNAV) and Miscellaneous
Amendments'' (67 FR 77326; Dec. 17, 2002). In that NPRM, the FAA
proposed to enable the use of space-based navigation aid sensors for
aircraft RNAV systems through all phases of flight (departure, en
route, arrival, and approach) to enhance the safety and efficiency of
the national airspace system.
Because at the time the EFVS NPRM was issued, the comment period
for the RNAV NPRM was still open, the FAA incorporated certain proposed
terminology, such as ``approach procedure with vertical guidance
(APV)'' and ``decision altitude (DA),'' from the RNAV NPRM into the
EFVS NPRM. This is discussed in detail in the preamble to the EFVS NPRM
(under ``Related NPRM'' at 68 FR 6803). The comment period on the RNAV
proposed rule closed on July 7, 2003. The FAA received numerous
comments on the terminology proposed in the RNAV NPRM, and must
consider those comments before issuing a final rule. Since those
comments are still under review, and the RNAV rulemaking action is not
yet a final rule, the FAA is not adopting the RNAV-related language in
the EFVS final rule.
In addition, on April 8, 2003, the FAA adopted certain terms from
the December 2002 RNAV NPRM by publishing a final rule, ``Designation
of Class A, B, C, D, and E Airspace Areas; Air Traffic Service Routes;
and Reporting Points' (68 FR 16943). The FAA also reorganized the
structure of its regulations concerning the Designation of Class A, B,
C, D, and E airspace areas, and it incorporated by reference two FAA
Orders--8260.3, U.S. Standard for Terminal Instrument Procedures
[[Page 1622]]
(TERPS) and 8260.19, Flight Procedures and Airspace. These portions of
the December 2002 RNAV NPRM were issued as a final rule to facilitate
the development of RNAV routes that are not restricted to ground-based
navigation systems.
IV. Discussion of Comments
IV.1. General
The FAA received more than 40 comments in response to the NPRM.
Commenters supporting the proposed rule commended the FAA for
developing a regulation to enable the use of enhanced visibility
technology that will increase levels of safety, provide operational
benefits, and increase aircraft operational efficiency. Some commenters
also believed that through the use of EFVS, aircrews will experience
increased situational awareness, improve approach completion rates,
reduce operational costs and significantly increase IFR safety margins.
Commenters opposed to the changes in the proposal requested that
the FAA withdraw the NPRM because they asserted that the NPRM is
inconsistent with current FAA advisory materials and the NPRM should be
coordinated through one of the FAA's rulemaking committees, that have
aviation industry participants. Some believed that the use of EFVS as
proposed in the NPRM would be so restrictive that it would limit
investment in vision system technologies and would limit the safety
benefits of such systems.
FAA's response: The FAA believes that the use of EFVS-equipped
aircraft will provide operational benefits and increase aircraft
operational efficiency in reduced visibility conditions. The FAA
believes that the NPRM is consistent with advisory materials and that
the best course for approval is to use the rulemaking process. The FAA
does not believe that this rule limits investment in vision-sensor
technologies. Responses to these and other issues are provided in
greater detail in the following subject-by-subject discussions.
IV.2. Flight Visibility and Visual References
Comment: There were several comments recommending the deletion of
Sec. 91.175(c)(2) on flight visibility because the visibility
determination is readily established in Sec. 91.175(c)(3) via
identifiable airport lighting systems and/or environment. Commenters
pointed out that the additional requirement of a pilot quantifying
flight visibility (as defined in 14 CFR part 1) with no other means
than a subjective determination adds an undue burden to the flight crew
and no means of substantiation. A commenter asserted that this flight
visibility requisite is especially an undue burden when the requirement
of Sec. 91.175(c)(3) has been accomplished. Conversely, commenters
suggested, continuation with an approach below the MDA or DH should be
predicated on the ability to see the runway environment, not a
numerical determination of the current flight visibility.
FAA's response: The FAA disagrees with the recommendation to delete
the ``flight visibility'' requirement of Sec. 91.175(c)(2) because the
requirement still applies to instrument approach procedures not
involving the use of EFVS. Not all operators will install an EFVS.
However, in accordance with the requirements in Sec. 91.175(l)(2),
this rule will allow the use of an EFVS to meet the requirement for
determining enhanced flight visibility, which is substantially
equivalent to the requirements in Sec. 91.175(c)(2). The intent of
this rulemaking is to allow the use of enhanced flight vision systems
to operate an aircraft below DH or MDA even when ``flight visibility''
requirements are not met. The FAA did not propose to change
requirements that apply to non-EFVS operations. The origin of the term
``flight visibility'' and ``visual references'' can be found in
Amendment No. 91-173, (46 FR 2280, January 8, 1981). In that amendment
of former Sec. 91.116 (recodified as Sec. 91.175 in 1989), the term
``visibility'' was clarified with the introduction of the term ``flight
visibility.'' Guidance was also provided for the specific ``visual
references'' that the pilot must identify at the MDA or DH to continue
the approach.
Amendment No. 91-173 clarified the term ``visibility'' in Sec.
91.116(c)(2) to specify that ``no pilot may operate an aircraft below
MDA or DH unless the flight visibility is not less than the visibility
prescribed in the standard instrument approach procedure being used.''
This revised requirement was necessary to make it clear that the
visibility referred to is the visibility from the aircraft and not
ground visibility. To simply state that, if the pilot has the runway in
sight, the flight visibility requirement is satisfied, is not always
valid. This concept may be valid for a Category I ILS approach but
would not be valid for other straight-in approaches such as a very high
frequency omnirange station (VOR) approach where the missed approach
point (the VOR navaid) is located on the airport. For example, if the
visibility for the VOR approach is 1 statute mile and the MDA is 600
feet (assuming no approach light system), and the pilot of an airplane
does not see the runway environment until passing over the runway
threshold at 600 feet, the pilot would have met the criteria for
identifying the runway, but with only 600 feet of visibility assured
would typically not be in a position to safely maneuver the aircraft
for a landing. In this hypothetical situation, the flight visibility is
less than 1 statute mile. However, if the flight visibility had been 1
statute mile, the pilot would have been able to identify the runway
threshold or runway lights at a distance sufficient to make a normal
rate of descent, using normal maneuvers from a visual descent point
(depicted on the approach chart or determined by the pilot) and
maneuver the aircraft for a landing. Simply saying that by identifying
one of the visual references of Sec. 91.175(c)(3) satisfies the
requirement for flight visibility, as stated on the instrument approach
procedure, is not enough for a safe operation.
It should be noted that the amendment to former Sec. 91.116 also
made it clear that the pilot must have the prescribed flight visibility
from descent below MDA or DH until touchdown by using as reference
items such as approach lights, threshold, threshold markings, etc.,
instead of towers, smoke stacks, buildings, and other landmarks that
may be located far from the end of the runway.
The objective of this rulemaking is to allow the use of any FAA-
certified EFVS that can display a real-time image of the external scene
topography and meet the requirements of Sec. 91.175(l) and (m). A
proposed EFVS could meet the requirements of Sec. 91.175(l) and (m)
and yet not be capable of distinguishing colors, and may not even be
capable of detecting the approach light system or runway lights, but
will provide an image of the runway surface and the metal structures
that encompass the approach lights or runway lights.
IV.3. Visual Cues (Visual References)
Comment: Several commenters also stated that the visual cues should
not be restricted to the two listed in the EFVS NPRM for the final
descent, but broadened to include any of those listed in Sec.
91.175(c)(3).
FAA's response: The FAA disagrees with these commenters. In the
NPRM, the FAA proposed that in order for the pilot to descend below the
DH or MDA when using the EFVS, one of two requirements had to be met:
(1) The approach light system (if installed) had
[[Page 1623]]
to be seen; or (2) both the threshold and the touchdown zone had to be
seen. If the approach light system was not seen (e.g., because it was
not installed or because it was not operating), the proposed rule would
have required that the pilot see both the threshold and the touchdown
zone in order to proceed below the DH or MDA. The FAA proposed a
compound requirement (i.e., the threshold and the touchdown zone) to
have a more stringent standard than what is allowed under existing
Sec. 91.175(c)(3) when using natural vision. The FAA proposed and
adopts in this final rule a more stringent standard because these EFVS
devices might not display the color of the lights or the runway
markings.
As proposed and as adopted in this final rule, the FAA's safety
goal was to specify certain visual references that would help the pilot
determine whether the aircraft was properly aligned with the runway of
intended landing. Thus, if the pilot using the EFVS can see the
approach light system, this is adequate to determine whether the
aircraft is properly aligned to continue the approach. If, on the other
hand, for whatever reason, the approach light system cannot be seen,
the FAA proposed, and finds that it is necessary, to have a compound
visual cue (visual references) requirement of the threshold and the
touchdown zone. The safety reason for this compound visual cue
requirement is that EFVS may not be capable of displaying runway
markings and the color of lights to identify the touchdown zone area of
the runway. Having a threshold identifying cue in sight and a touchdown
zone cue in sight should give the pilot an adequate pattern of
recognition to determine whether the aircraft is properly aligned with
a runway and thus, enable the pilot to determine whether to continue or
to execute a missed approach.
In the proposed Sec. 91.175(l)(3)(ii), the FAA used the language,
``the runway threshold and the touchdown zone.'' In the final rule, for
clarification purposes, the FAA is specifying those items that it
considers as identifiers of the runway threshold and touchdown zone.
Thus, in order to identify the runway threshold, the pilot needs to be
able to see the beginning of the runway landing surface, the threshold
lights, or the runway end identifier lights. In addition, in order to
identify the runway touchdown zone, the pilot needs to see the runway
touchdown zone landing surface, the touchdown zone lights, the
touchdown zone markings, or the runway lights. When the FAA refers to
``runway lights'' in Sec. 91.175(l)(3)(ii)(B)(4), this does not mean
all of the runway lights. Instead, it means only those runway lights
that together with the threshold identifier would help the pilot
recognize whether he or she is approaching the runway of intended
landing. Therefore, in this final rule, Sec. 91.175(l)(3) is revised
to read as follows:
(3) The following visual references for the intended runway are
distinctly visible and identifiable to the pilot using the enhanced
flight vision system:
(i) The approach light system (if installed); or
(ii) The following visual references in both paragraphs
(l)(3)(ii)(A) and (B) of this section:
(A) The runway threshold, identified by at least one of the
following:
(1) The beginning of the runway landing surface;
(2) The threshold lights; or
(3) The runway end identifier lights.
(B) The touchdown zone, identified by at least one of the
following:
(1) The runway touchdown zone landing surface;
(2) The touchdown zone lights;
(3) The touchdown zone markings; or
(4) The runway lights.
IV.4. Restricted Visual References
Comment: One commenter noted that some visual references currently
present in Sec. 91.175(c)(3) (for example, the runway end identifier
lights, the runway or runway markings, and runway lights) would be lost
to EFVS users under proposed Sec. 91.175(l)(4).
FAA's response: The FAA does not agree. Section 91.175(c)(3) of the
current regulations relate to a different set of circumstances than
proposed Sec. 91.175(l)(4). In the EFVS NPRM and this rule, the pilot
at 100 feet above the touchdown zone elevation of the runway of
intended landing must see the lights or markings of the threshold or
the lights or markings of the touchdown zone using natural vision. Some
of the items listed in Sec. 91.175(c)(3) would not be visible at 100
feet above the touchdown zone elevation.
IV.5. Harmonization
Comment: A commenter pointed out that a stated goal of both the
Joint Aviation Authorities (JAA) and the FAA is harmonization. This
commenter believed that deleting the reference to flight visibility and
continuing to use the visual references of Sec. 91.175(c)(3) would
harmonize the FAA and JAA regulations.
FAA's response: The topic of ``flight visibility'' could be a
subject for future JAA harmonization discussions, but at this time
there is no corresponding JAA provision. This comment is not within the
scope of this rulemaking because the FAA did not propose to remove the
requirement for flight visibility in Sec. 91.175(c)(2).
IV.6. Airport Lighting Systems
Comment: Several commenters stated that the EFVS should be
compatible with the airport lighting systems. One commenter noted that
recent information indicates that some newly installed airport lighting
systems will use current technology light emitting diode (LED) systems
that do not have a large infrared signature. According to the
commenter, these LED systems potentially are not visible to current
enhanced vision systems (EVS).
FAA's response: The FAA acknowledges that some EFVS may perform
differently in detecting airport lighting systems. However, the rule
provides the pilot with various other identifiers to meet the visual
reference requirement of Sec. 91.175(l)(3). If the pilot is unable to
identify any of the required visual references in Sec. 91.175(l)(3)
with the EFVS at the DH or MDA, a missed approach must be conducted.
IV.7. Electromagnetic Spectrum
Comment: One commenter noted that an EFVS may not be limited to
operations outside the visible frequencies of the electromagnetic
spectrum. This system restriction is omitted for the proposed
definition of EFVS in 14 CFR part 1. This commenter recommends that the
FAA disregard the last phrase in the NPRM preamble background
discussion for ``Previous type designs'' that states `` * * * which
operates outside the visible portion of the electromagnetic spectrum''
and allow the proposed EFVS definition to provide the description.
FAA's response: The FAA agrees with this commenter that an EFVS may
be designed to operate within the visible portion of the
electromagnetic spectrum. The definition of an EFVS in part 1 does not
prohibit these types of EFVS and therefore the rule does not have to be
amended.
IV.8. Limitations of Systems
Comment: One commenter proposed that the FAA add a concluding
paragraph to the revision of proposed Sec. 91.175 in lieu of the
proposed language that stated: ``Notwithstanding provisions of
paragraphs above, the Administrator may approve the use of Enhanced
Vision Systems (EVS) and procedures meeting requirements other than
those specified, if: (1) The systems and procedures proposed are shown
to have equivalent or better performance than other approved systems,
are operationally safe, effective, and reliable for ground and flight
operations
[[Page 1624]]
including: Taxi, takeoff, climb, cruise, descent, approach, landing,
roll-out, or missed approach as applicable, and, (2) if visual
reference requirements apply, the pilot is able to determine that
flight visibility is adequate for safe takeoff or landing.'' The
commenter stated that realization of EVS benefits and other
significant, technology driven, operational and safety enhancements are
dependent on structuring language within the NPRM that encourages
further technological development and does not specifically limit
system design. It is important to avoid rulemaking language that
narrowly defines systems or technologies, but instead addresses
fundamental requirements. The commenter believed that approval of EVS
or other systems should be based on demonstrating equivalent levels of
safety and performance to that of currently approved instrument
approach and landing systems.
FAA's response: The FAA disagrees with the commenter and believes
that the regulatory language proposed by the commenter is too open-
ended and non-specific to be applied as a rule. This final rule will
allow an aircraft to be operated to lower altitudes (DH or MDA) than
presently permitted for straight-in instrument approach procedures
other than Category II or Category III if the conditions of the
proposed language are met. Thus, this final rule provides an
operational benefit (operations to lower altitudes in marginal weather)
for those who equip their aircraft with this new technology and who
meet the other conditions of the new rule. In addition, many of the
commenters' proposed uses of an EFVS are beyond the scope of this
rulemaking because the FAA did not propose to allow the use of EFVS to
meet any other regulatory requirements. However, the proposed
rulemaking does not impose restrictions on other voluntary uses of an
FAA certified EFVS where the pilot is not using the EFVS to meet a
regulatory requirement, i.e., situational awareness.
The FAA does not intend to discourage technical innovation, and
this rule does nothing to hinder innovation. Instead, this rule
provides a way for a new technology that has been developed, tested,
and certified by the FAA to be used in a way that provides operational
and safety benefits. The rule provides an acceptable alternative to the
previously existing requirements for flight visibility and allows
operations below the DH or MDA without affecting the standard
instrument procedures or the prescribed visibility minima. Without the
use of EFVS, it would not be possible to offer these significant
operational benefits. The operational concepts for using other
innovative technology may differ from that underlying this rule.
IV.9. Other Technologies
Comment: Several commenters stated that the NPRM excluded the use
of other types of technology that can achieve the same results as EFVS,
and that the NPRM would discourage technology and innovation by
precluding or seriously discouraging the use of other technologies such
as synthetic vision systems (SVS). Another commenter noted several
potential advantages of an SVS over an EFVS. EFVS unpredictably has a
limited vision capability while SVS capability would be reliably
available for much farther distances (such as full scene capability
from the final approach fix), allowing for improved approach stability
and lower crew workloads.
A commenter noted that an EVS is currently using a raster
(television) display technology, while SVS can be implemented in
``Stroke'' (line drawing) technology. Raster inherently obscures the
entire view of the outside world through the HUD while Stroke has no
obscuration at all except where the actual relevant material, such as
runway outlines, are being displayed. The FAA/USAF Synthetic Vision
Technology Demonstration Program documented instances where the crew
using HUD EVS were unable to see real visual cues due to the EVS raster
obscuration of the visual runway view, forcing unnecessary go-arounds.
This commenter also stated that EVS images in minimal weather will
be limited to ``improved eyesight'' giving only a few runway lights. An
SVS-enhanced solution would give complete approach lead-in, as well as
outline of the load bearing boundaries of the runway.
This commenter believed that at most runways in wet, icy, or snowy
weather, EVS is unpredictably incapable of providing any indication of
where the desired touchdown point is on the runway or the extent of the
touchdown zone (typically extending from 500 feet to 3,000 feet down
the runway). SVS technology would be able to reliably provide both.
FAA's response: The FAA acknowledges that a synthetic vision system
could have certain display advantages in comparison to EFVS with
respect to information content and method of presentation and does not
intend to prohibit future implementation of standard SVS instrument
approach procedures. However, the proposed rule was intended to provide
an analogous alternative to Sec. 91.175(c)(2) (flight visibility) for
descent and operation below DH or MDA, to conduct straight-in
instrument approaches, other than Category II or Category III, with
standard minima. The key difference between SVS and EFVS is that an
EFVS provides an independent real-time view for the pilot. Whereas, an
SVS is comprised, in part, of a database component, a precise
navigation component, instrument data interfaces and a processing
component that would compute and ``draw'' the forward view based on
what the external view should be if the data base and navigation
components are valid. The database-derived SVS display is not a real-
time source of forward scene information as is the EFVS sensor-based
image. Although an SVS may display a synthetic view of the runway, it
is incapable of displaying a real-time view of the external scene and
the pilot would not be able to determine if the runway were
contaminated by water, ice, or snow. Therefore, an SVS display cannot
serve as an alternative means of complying with Sec. 91.175(l)(3) for
descending below DH or MDA.
IV.10. Regulatory Bar To Use of Systems Such as SVS
Comment: One commenter stated there is no regulatory bar to use of
systems such as SVS. In fact, systems having the characteristics of SVS
were also developed and implemented for use in the 1960s and 1970s.
Specific U.S. civil examples are available. Further, according to the
commenter, the NPRM provided no technically sound basis to justifiably
and inherently discriminate between the merits of SVS, EVS, and other
systems for certain specific low-visibility related tasks or
applications.
FAA's response: An SVS cannot provide enhanced flight visibility,
especially the capability to show a real-time image of an aircraft or
vehicle on the runway of intended landing. Although an SVS has been
approved for flying an instrument approach procedure, it has not been
approved for operations below the authorized DH or MDA. Therefore, an
SVS cannot be used below the DH or MDA unless the flight visibility is
not less than the visibility prescribed in the standard instrument
approach procedure being used (Sec. 91.175(c)(2) and unless at least
one of the items in Sec. 91.175(c)(3) is distinguishable. Operations
below the DH or MDA are only authorized if the requirements of Sec.
91.175 (c)(2) and (c)(3) are met or the requirements of Sec.
91.175(l)(2) and (l)(3) are met. There is a bar to using an SVS to fly
a standard
[[Page 1625]]
instrument approach procedure and descend below the authorized minima
(DH or MDA) without having the required flight visibility or enhanced
flight visibility. There is also a bar to using an SVS, even above the
DH or MDA, unless the FAA has specifically approved the operation.
IV.11. Differentiation Between Runway and Taxiway
Comment: A commenter stated that the NPRM would not have required
that a capability exist to differentiate a taxiway or other runway
similar environment (e.g., lighted highway or drag-strip) from a runway
environment. EVS systems are usually incapable of distinguishing
taxiway lighting or even taxiway environments from runway environments,
especially when considering nonprecision runways. Examples of these
difficulties include that the sensor cannot determine the visual color
of the lighting system, and for imaging radar-based systems, the
radiated heat pattern is different than the visual light distribution
(taxiway lights do not project light upwards at the same angle as
runway lights). To mitigate this problem, the pilot must see the runway
visually at 100 feet above the touchdown zone elevation to land the
aircraft.
FAA's response: The FAA acknowledges that some enhanced flight
visibility systems may not work as well as others to adequately portray
the forward scene and the visual references listed in the rule. During
certification of the EFVS installation, the applicant must demonstrate
that pilots will be able to use the EFVS to distinctly see and identify
these visual references and determine whether the enhanced flight
visibility is no less than the prescribed minimum. The EFVS will be
tested in a variety of environmental conditions and at several
different runways. The FAA will not approve a system that is found to
be prone to misidentification of the listed visual references or in
other ways does not perform its intended function.
The FAA believes it is not necessary to explicitly require the EFVS
to distinguish runways from taxiways. However, the rule does list
specific visual references of an approach light system or a runway and
touchdown zone that would distinguish a runway from other features of
the airport environment, at least one of which must be distinctly
visible and identifiable using the EFVS and the rule requires that the
touchdown zone be distinctly visible and identifiable to the pilot. By
meeting these requirements, the pilot can know that the aircraft is
approaching the desired runway, and not a taxiway. If a runway feature
and a touchdown zone feature cannot be distinguished from a taxiway
feature, then the runway is not distinctly visible and identifiable.
The rule provides for a safe operation, because the pilot must
execute a missed approach if at any time between the DH or MDA and 100
feet above the touchdown zone elevation the visual references are not
distinctly visible and identifiable by using the EFVS. Furthermore,
upon reaching 100 feet above the touchdown zone elevation, the pilot
must be able to see and identify, without reliance on EFVS, the
threshold (lights or markings) or touchdown zone (lights or markings)
of the intended runway. If at 100 feet above the touchdown zone
elevation, the pilot cannot see the threshold (lights or markings) or
the touchdown zone (lights or markings), the pilot must execute a
missed approach.
IV.12. Obstacle Clearance
Comment: One commenter stated that giving obstacle avoidance credit
to EFVS is incorrect. Many nonprecision approaches are constructed such
that the MDA and visibility charted provide the crew with the
capability to see and avoid obstacles or obstructions in the possible
paths descending from the MDA or from the terminating point of the
approach.
This commenter asserted that allowing EFVS to be used in lieu of
charted flight visibility may put the aircraft at serious risk, since
many obstructions or obstacles are not visible to EVS sensors and thus
would not be displayed to a crew relying on an EFVS to transit the area
below the MDA and 100 feet above the touchdown zone elevation. Worse,
according to the commenter, is the ability of EVS to see many types of
natural or cultural features is generally unpredictable due to thermal
characteristics.
FAA's response: The FAA agrees with the commenter that some EFVSs
may not be able to consistently detect obstacles in the visual segment
of an instrument approach procedure under certain conditions. Many of
the obstacles the commenter refers to would not be a problem if the
pilot complies with the same three requirements as Sec. 91.175 (c) for
a pilot to descend from the MDA on a nonprecision approach. The three
requirements applicable to Sec. 91.175 (c) and (l) are: (1) Pilot must
observe that the enhanced flight visibility (or flight visibility) is
not less than the visibility specified for the procedure; (2) at least
one of the specifically listed visual references must be distinctly
visible and; (3) the aircraft must continuously be in a position from
which a descent to a landing on the intended runway can be made at a
normal rate of descent using normal maneuvers.
If a pilot meets all of the requirements of Sec. 91.175 (l), the
pilot should have adequate visibility to see the runway environment. In
addition, while an EFVS may not detect all of the obstacles the
commenter refers to, an EFVS may reveal some of them. For example,
there may be cues observable in the EFVS display that would indicate
that an obstacle exists, other than a distinct image of an obstacle.
For example, a partial obstruction of the runway may indicate terrain
between the aircraft and the runway.
The FAA acknowledges a key point made by the commenter, that it is
uncertain that the EFVS will always enable the pilot to detect all
obstacles in the visual segment of the approach. A similar risk is
present today because it is also uncertain that pilots will always be
able to detect obstacles visually when operating conventionally under
Sec. 91.175 (c). Adverse visual conditions, such as low contrast,
shadows, snow cover (especially coupled with falling snow and/or
overcast conditions, i.e., ``whiteout''), and situations of similar
obstacle and background coloring can occur even when flight visibility
and the other requirements for descent below MDA are satisfied.
The risk for a nonprecision approach using EFVS is significantly
mitigated by the rule by only permitting reliance on an EFVS to
straight-in approaches. The FAA believes it is unlikely that a pilot
following straight-in instrument approach procedures will encounter an
object in the flight path. The FAA does acknowledge that it is possible
for an EFVS to not detect obstacles in the visual segment of an
approach even if the pilot has the required enhanced flight visibility.
However, the FAA believes that obstacle clearance can be maintained, if
the pilot uses the recommended procedures below to fly a straight-in
instrument approach procedure with a MDA, and uses the flight path
vector and flight path angle reference cue displayed by the EFVS to
monitor and maintain the desired vertical path and begins descent below
the MDA:
(1) At the VDP, if charted, or a reasonably calculated visual
descent point; or
(2) Using the descent angle published on the instrument approach
procedure or if a descent angle is not published, a descent angle as
high as suitable for that type of aircraft.
[[Page 1626]]
To clarify the FAA's intent as to which topographical features that
an EFVS must detect and display, the FAA is amending proposed Sec.
91.175 (m)(1) to state that an EFVS must be able to display
topographical features of the airport environment. It is not the FAA's
intent to require an EFVS to detect all obstacles while transiting the
visual portion of the final approach segment.
IV.13. Weather-Related Comments
Comment: One commenter recommended that the FAA modify Sec.
135.225 (b) and associated paragraphs to accommodate authorized
operators using EFVS by allowing an approach to be initiated if
reported weather minimums are lower than the minimums established for a
specific EFVS. The commenter stated that reported visibility, measured
by a transmissometer, is not a reliable indicator of EFVS performance
at or below DH or MDA because it does not measure visibility in the
same part of the electromagnetic spectrum as the EFVS. The commenter
stated that this recommendation would increase the probability of a
successful landing with operational and safety benefits.
FAA's Response: The FAA disagrees that modifying the reported
visibility requirement for commencing the approach would increase
safety. While the FAA agrees that the transmissometer does not operate
in the same portion of the electromagnetic spectrum as the EFVS, its
measurements are just as representative of the visibility conditions
at/below 100 feet height above touchdown zone elevation as they are
today. Even today, in conventional approaches, the reported visibility
is not a totally reliable indicator of flight visibility at the DH or
MDA, but is more representative close to the runway, where the pilot
must use the visual references to complete the manual landing. This
commenter's recommendations are outside the scope of the NPRM.
IV.14. Equipment-Related Weather Minimums
Comment: A commenter stated that the altitude criterion for EFVS is
not based on the capability of the equipment and that specifying an
absolute altitude as a minimum altitude for EFVS usage during approach
and landing inhibits the incentive to advance optics technology to a
level at which weather obscurations will be transparent to the EFVS.
The commenter stated that by providing latitude for EFVS minimum
altitude usage, the FAA could preclude additional changes to the
regulation in the future or the need for imposing special conditions on
equipment certification.
This commenter recommended that the minimum altitude for operation
with an EFVS be predicated on the specific equipment installed and
certified by the FAA (or approved by the FAA for foreign registered
aircraft). The commenter proposed that the FAA change to Sec.
91.175(l)(4) to say: ``At and below the minimum altitude at which the
EFVS was certified or approved by the FAA, the * * *.''
Another commenter stated that once the performance limit for a
particular EFVS is reached, the use of that particular EFVS is no
longer approved for landing credits, and the requirements of Sec.
91.175(c)(3) become applicable. As a result, Sec. 91.175(l)(4) is no
longer necessary.
FAA's response: The FAA disagrees with the commenter's premise that
the transition to outside visual references at 100 feet above the
touchdown zone elevation is an altitude criterion for EFVS. The rule
does not establish an altitude criterion for use of EFVS, per se, nor
does it establish a minimum use height, in the same sense that such
limitations are placed on autopilots, for example. The purpose of the
rule is to apply the same DH or MDA and visibility minima prescribed in
the standard instrument approach procedure when EFVS is used (i.e.,
EFVS does not reduce the minima), so it would be inconsistent to base
an altitude criterion on the capability of a particular EFVS.
The FAA also disagrees with the comment that the rule establishes a
performance limit for EFVS. Section 91.175(l)(4) requires that the
pilot transition to the actual outside view by 100 feet above the
touchdown zone elevation. The requirement is based on the operational
need for the pilot to obtain visual contact (through the window) with
the runway features to land, and is consistent with the time-tested
operational concept of Sec. 91.175(c)(3)(i). Section 91.175(l)(4) is
necessary because it identifies the requirement for pilots using EFVS
to make the transition to outside references by 100 feet above the
touchdown zone elevation. While the commenter is correct that the
references listed in (l)(4) are similar to those in listed in (c)(3),
the focus of (l)(4) is on the transition to outside visual references
that are especially needed for the manual landing (e.g., runway
threshold and touchdown zone).
The FAA recognizes that some enhanced flight vision systems may
perform better than others. If, during certification, an EFVS is not
found safe to use down to 100 feet above the touchdown zone elevation,
then it will not be approved because it cannot perform its intended
function.
IV.15. Operational Intent of the Rule
Comment: One commenter stated that in normal IFR operations,
current Sec. 91.175 requires that the pilot have clear and
unobstructed visibility of the approach lights to continue below the DH
or MDA. The NPRM seeks to augment the visibility requirement by
permitting the use of a sensor-based imaging device in conjunction with
a HUD to enhance the pilot's visibility down to the 100-foot level, at
which altitude the existing visibility requirements of Sec. 91.175
again become the operant rule, and the pilot must make the decision
whether to go around or to land the airplane based on unassisted visual
references only (not based on the EFVS imagery). According to this
commenter, the proposed rule would apply primarily to ``fly down and
take a look'' approach operations. In order to avoid controversy in
application of the proposed rule, this commenter recommends that the
FAA clarify the operational intent of the proposal, to include specific
visibility.
FAA's response: The rule does not augment the visibility
requirements of Sec. 91.175(c), but instead provides an alternative
requirement (e.g., enhanced flight visibility) for operation below the
DH or MDA. The use of EFVS does not alter the visibility requirements
for commencing the approach. Today, part 121, 125, and 135 operators
may not initiate an instrument approach procedure (Sec. 121.651(b),
Sec. 125.381(b), or Sec. 135.225(b)) unless the reported visibility
is equal to or more than the visibility minimums prescribed for that
procedure. This requirement does not exist for part 91 operators, which
implies that they may commence the approach when reported visibility is
below minimums. In addition, EFVS does not affect the visibility or
systems and pilot qualification requirements for Category II/III
operations. By 100 feet above the touchdown zone elevation, the pilot
must be able to see and identify visual references without reliance on
EFVS. While use of EFVS during Category II and III operations may be
permissible, such use must be specifically authorized as part of the
operator's authorization for Category II and III approaches either by
operations specifications for part 121, 125, or 135 operations or per
Sec. 91.189.
[[Page 1627]]
IV.16. Operational Benefits for Part 121, Part 125, and Part 135
Operations
Comment: Several commenters stated that there should not be any
difference between part 91 and parts 121, 125, and 135 with respect to
the requirements for commencing the approach with EFVS. Several
commenters recommended that pilots operating under parts 121, 125, and
135 should be able to begin the approach based on having an EFVS
regardless of the reported weather.
Another commenter proposed that, for part 121 and part 135,
operations equipped with a certified EFVS be allowed to initiate the
approach in weather conditions reported as low as 1,200 feet RVR or \1/
4\ mile visibility.
Another commenter recommended deleting Sec. 121.651(b)
(requirements for commencing an approach) if the operator has a
certified EFVS.
FAA's response: The FAA disagrees. The commenters' recommendations
are outside the scope of the NPRM and would not provide for an adequate
level of safety for operations conducted for compensation or hire for
the following reasons. The proposal would undermine the current safety
standards of not permitting a pilot to begin an instrument approach
procedure if current weather reports are not available for the
procedure or they report a below-authorized weather condition for
operations conducted under parts 121, 125, or 135. These weather
reports provide necessary safety information to pilots in addition to
visibility information.
IV.17. Part 121, Part 135, and Part 129 Operations
Comment: One commenter stated that extending the NPRM text to parts
121, 135, and 129 would be potentially unsafe as written (e.g., systems
strictly meeting this rule could nonetheless lead pilots and aircraft
into unsafe conditions), and are as yet operationally unsupported and
unjustified. It would be most inappropriate to include specific EVS
provisions in parts 121, 135, and 129 in the proposal at this time.
Operational utility and safety of operations as implied by the NPRM, as
well as legitimate ``proof of concept,'' are far from established at
this point.
The commenter stated that part 129 operators, JAA, and other
European representatives recently expressed concerns about such
operations, particularly considering that those EVS operations are more
appropriately termed Category II or III, than Category I.
FAA's response: The FAA disagrees that part 121, part 129, and part
135 operators cannot operate safely under this rule. This rule
parallels the well-tested safe approach procedures of Sec. 91.175(c).
The commenter did not identify how these operations will be unsafe. The
FAA did not receive any response from the JAA or European
representatives regarding this rule.
IV.18. Operational Experience Before Credit for Lower Minimums
Comment: A commenter stated that, as with any new aircraft system,
EFVS operational experience must be documented prior to further
consideration for EFVS credit for lower minimums. Any EFVS operational
limitation should be documented within the operator's AFM supplement.
FAA's response: The FAA does not believe that operational
experience is necessary for an approved EFVS used in accordance with
the rule because this rule does not provide for the use of EFVS to
obtain credit for lower minima. The FAA agrees that any EFVS operating
limitations found during certification should be stated in the AFM/RFM
supplement.
IV.19. Takeoff Minimums for EFVS
Comment: Several commenters stated that proposed Sec. Sec. 91.175,
121.651, 125.381, and 135.225 make no provisions for the enhanced
vision flight vision system to be used to meet takeoff visibility
requirements. Given that the system can be used to meet flight
visibility requirements during approach, it follows that some credit
should be able to be derived for takeoff operations below the
established takeoff visibility.
FAA's response: The use of EFVS to meet takeoff visibility is
beyond the scope of this rulemaking. This rule applies only to approach
to straight-in landing operations below DH or MDA using an EFVS. The
FAA did not propose the use of EFVS during takeoff.
IV.20. Rule Should Be an Advisory Circular (AC)
Comment: Several commenters asked why the FAA proceeded by
rulemaking action instead of by AC. One commenter also stated that the
NPRM could inappropriately set a precedent that rulemaking is required
to implement new technology when rulemaking is not required.
FAA's response: The FAA is proceeding by rule instead of AC because
this rule permits the use of new technology for straight-in approach
landings by in essence creating an exception to the existing regulatory
prohibitions in Sec. 91.175(c)(2). An agency is required to conduct
rulemaking when it considers changing an existing policy limitation in
the rules. In this case, if an EFVS is approved by the FAA, meets all
the requirements of Sec. 91.175(m) and is determined to provide an
equivalent level of safety, this operational rule will provide an
alternative to the flight visibility requirement of Sec. 91.175(c)(2)
and allow the operator to descend below the DH or MDA if the
requirements of Sec. 91.175(l)(2) and (l)(3) are met.
IV.21. Terminology: Category I and Advisory Circulars
Comment: Several commenters stated that in accordance with the
recently published AC 120-29A, ``Criteria for Approval of Category I
and Category II Weather Minima for Approach,'' dated August 12, 2002,
terminology for approach categories have been changed. A Category I
approach is any approach that has a DH of not less than 200 feet AGL
and a visibility requirement of not less than \1/2\ statute mile. The
reference to precision and nonprecision approaches is no longer
applicable and the terminology has been redefined. These commenters
believed that conforming to a common terminology, as presented in AC
120-29A, provides additional clarity in the regulation.
FAA Response: The FAA disagrees with the comment that the NPRM was
not consistent with the intent and direction of AC 120-29A. That
advisory circular discusses the terms for Category I approaches which
includes nonprecision approaches, more specifically, an approach
without vertical guidance. Although this definition for a Category I
approach has been more commonly used in operations specifications for
part 121, part 125, part 129 and part 135 operators, the FAA wants to
make it clear that an EFVS could be used with a nonprecision approach
for operators not using operations specifications.
AC 120-29A also mentions the generic term ``enhanced vision
system'' (EVS). While this rule does not preclude the limited use of
EFVS as described in AC 120-29A, it does permit an approved EFVS to be
used to determine ``enhanced flight visibility'' which is a significant
additional benefit for operators who were limited to using EFVS for the
purposes described in the AC.
IV.22. Coordination Through TAOARC and AWO Process
Comment: Some commenters stated that the NPRM should not be issued
in its current form and any subsequent revisions to the NPRM should be
coordinated through both the All-Weather Operations (AWO)
[[Page 1628]]
harmonization process and the FAA TAOARC processes and be consistent
with other related NPRMs (e.g., RNAV, Docket No. FAA-2002-14002, and
Special Operating Rules for the Conduct of Instrument Flight Rules
(IFR) Area Navigation Systems (RNAV) in Alaska, Docket No. FAA-2003-
14305).
FAA's response: The comments about the proposed changes in
terminology for approach categories in the RNAV NPRM (Docket No. FAA-
2002-14002) are not within the scope of the notice for this rulemaking
and are not incorporated into this final rule. The Alaska Special
Federal Aviation Regulation (SFAR) only addressed en route requirements
for RNAV equipment and training and did not address RNAV instrument
approach procedures.
The FAA disagrees with the comment that the current wording,
especially definitions, of the NPRM and any subsequent revisions to the
NPRM proposals should be coordinated through both the AWO harmonization
and FAA TAOARC processes, and be consistent with the other noted NPRMs.
This final rule action does not preclude persons from submitting
recommendations concerning EFVS through their representatives on the
AWO working group.
IV.23. EFVS Flight Path Performance
Comment: One commenter stated that the proposed requirements of the
NPRM pose safety concerns. According to the commenter, representatives
of European authorities, and others, correctly identify that some of
the proposed operations with the above systems are, and should be
appropriately classified and recognized as, Category II and Category
III operations. Yet the proposed EFVS do not appear to come close to
meeting the path performance standards necessary for safety for such
operations. (See AC 120-28D, ``Criteria for Approval of Category III
Weather Minima for Takeoff, Landing, and Rollout.'') The NPRM cited no
evidence that adequate flight path performance can be demonstrated with
imaging systems alone, whether TV, imaging radar (IR), or radar based.
The commenter stated that current operating history with such systems
in research and development programs and military operations indicates
the opposite conclusion, which is why such operations often rely on use
of autoland. Further, this commenter believed, there is no evidence
presented in the NPRM that the ``aircraft state or guidance elements''
cited can perform to the levels necessary for either Category II or
III, and particularly not for operations below 100 feet height above
touchdown (HAT), flare, and rollout, or for missed approach, where such
EVS systems are likely to lead a pilot without guidance assistance.
FAA's response: The FAA disagrees. The FAA believes the commenter
misunderstood the purpose and applicability of the NPRM regarding the
use of EFVS in the conduct of instrument approach procedures. This rule
does not permit an operator to rely on an EFVS for category II or
category III type approaches when an EFVS is relied upon for enhanced
flight visibility pursuant to Sec. 91.175(l). Use of the EFVS is an
alternative means to comply with flight visibility requirements. To
clarify any misunderstandings concerning the applicability of this
rule, the FAA is adding language in the text of the rule in Sec.
91.175(l)(1) to limit the application of this rule to straight-in
instrument approach procedures other than category II and category III
operations. Advisory Circular 120-28D and AC 120-29A both provide
guidance for the criteria for approval of weather minima (Category I,
II, III) and the use of enhanced vision systems (EVS). The guidance
provided in the ACs describe the functionality of EVS to ensure the
accuracy or integrity of other flight guidance or control systems in
use during Category I, II, or III operations. The proposals in the NPRM
described a new kind of functionality for EVS/EFVS.
EFVS can be used to enable pilots to determine ``enhanced flight
visibility'' in lieu of ``flight visibility.'' Whether EFVS approved
for determining ``enhanced flight visibility'' can also be approved for
ensuring the accuracy or integrity of other flight guidance or control
systems will depend upon whether the candidate system can be
demonstrated to be acceptable to the FAA in a proof of concept
evaluation as well as meeting the approval criteria in AC 120-28D or AC
120-29A.
IV.24. Inconsistency With Terminology in AC 120.28D or AC 120.29A
Comment: One commenter stated that the NPRM terminology presented
an inappropriate use and meaning of Category I. Since the 1980s in
operations specifications, and since 1999 in FAA criteria, this use of
Category I terminology is incorrect and inappropriate. Since the 1980s,
Category I applies not only to United States ILS, GLS, and other
instrument approaches in operations specifications, but since 1999 has
been additionally recognized in other appropriate FAA advisory circular
criteria. Hence, the use of Category I and II terminology in the NPRM
is incorrect and inappropriate and should be withdrawn. Accordingly,
Category I, II and III definitions should be retained for U.S. use as
currently described in FAA ACs 120-29A and 120-28D, and current
operations specifications. If and when ICAO definitions for Category I,
II, and III are updated through FAA/JAA AWO or other harmonization
activities, or otherwise agreed in ICAO, the United States should
consider further amendments of these terms. Hence, these provisions are
much too technology-specific, misleading, and potentially unsafe as
written (e.g., systems strictly meeting this rule could nonetheless
lead pilots and aircraft into unsafe Category II and III conditions)
and are operationally unsupported and unjustified. Other commenters
made similar statements.
FAA's response: The FAA disagrees with this comment for the reasons
discussed in the response to the EFVS flight path performance comment.
(See ``IV.23. EFVS flight path performance'' above.) In addition, the
FAA disagrees that this final rule will potentially result in unsafe
operations as written. The FAA believes that the use of EFVS will
result in an equivalent level of safety for those operators who choose
to equip their aircraft with that equipment. As with any aircraft
system, to ensure the safety of operations in which EFVS is used, the
operator must comply with the operating limitations specified in the
Airplane or Rotorcraft Flight Manual and, for commercial operators, any
conditions and limitations regarding its use are specified in the
operator's operations specifications.
The rule will not lead pilots and aircraft into unsafe Category II
or Category III conditions. The safety of the EFVS concept of
operations, unlike the concept for Category II or Category III
operations (e.g., higher integrity, more rigorous guidance and
navigation accuracy to achieve lower minima), is that EFVS provides an
alternate means to satisfy the visibility requirements without reducing
the visibility minima. The rule, following an operational concept
analogous to that of Sec. 91.175(c), requires the pilot to meet the
prescribed visibility minima, based on ``enhanced flight visibility''
in lieu of ``flight visibility;'' to distinctly see and identify either
(1) the runway threshold and the touchdown zone, or (2) the approach
light system; and, by 100 feet above touchdown elevation to see the
runway references needed for a manual landing without reliance on EFVS.
Further, the rule does not relieve commercial operators from the
visibility requirements for commencing the
[[Page 1629]]
approach. Based on these facts and the clarifying language added to
Sec. 91.175(l)(1), the FAA does not believe the rule will mislead a
pilot into unsafe conditions.
IV.25. EFVS Use for Category II & Category III Approaches
Comment: Several commenters recommended that EFVS be used for
Category II and III approaches, which the proposed rule did not seem to
permit. The EFVS use should be permitted for situational awareness and
for visual approach conditions as well as for Category I, II, and III
approach conditions. This should apply to autoland and to hand-flown
approaches.
Commenters recommended that the FAA:
[sbull] Clarify the intended usage of a certified EFVS during a
Category II or III approach.
[sbull] Allow the EFVS to be operated during a Category II or III
approach.
[sbull] Clarify what is meant by ``the stringent reliability,
redundancy and other criteria that would be applicable for use of EFVS
for Category II and III approaches'' as stated in the EFVS NPRM.
Another commenter proposed that the rule state: ``Any approach
using EFVS will de facto be equivalent to a CAT2+ type of approach, as
there is no more flight visibility requirements and EFVS can be used
down to 100 ft.'' The commenter stated that in order to be consistent
with current rules and to ensure a correct level of safety, approaches
conducted with EFVS systems should offer a sufficient safety level and
architecture compatible with current Category II rules. The commenter
stated that EFVS software design assurance levels should be the same as
for equipment used to support Category II and Category III operations.
Therefore, the commenter stated, EFVS-based operations should require
that: (1) The aircraft is equipped with at least 2 DO-178B Level B
qualified ILS receivers, with comparison monitors; (2) ILS or MLS
ground transmitters used during an EFVS approach should comply with
Category II safety level; and (3) EFVS sensor imaging process should
ensure that no picture lockup can happen. EFVS sensor image processing
software should be at least DO-178B level C qualified.
FAA's response: The final rule does not permit an operator to rely
on an EFVS for Category II and III approach procedures, and the final
rule does not change the requirements for Category II and III
operations. Any future proposed use of EFVS for Category II and III
operations must comply with current regulatory requirements found in
Sec. Sec. 61.67 and 61.68, 91.189 through 91.193, 121.651(d)(3),
121.567, 125.325 or 135.78 that Category II and Category III operations
must be authorized by the Administrator. Advisory Circulars AC 120.29A
and AC 120.28D provide guidance concerning the stringent reliability,
redundancy and other criteria for equipment used in Category II and
Category III operations.
Proposed revisions to Sec. 91.175(l) do not have provisions for
Category II and III operations because that section only applies to
straight-in approach operations, i.e., approaches with a DH or MDA no
less than 200 feet HAT. The NPRM did not intend to unconditionally
prohibit the use of EFVS during Category II and Category III
approaches. If EFVS is used during Category II or Category III
operations, it is only in addition to the other required equipment,
procedures, crew qualifications and so on, provided that the EFVS does
not interfere or degrade the low visibility operation. The requirements
and criteria for the equipment, procedures, training, maintenance, and
airport features to be used for Category II and Category III approaches
are well established and must still be complied with, regardless of
EFVS. The use of EFVS in Category II or III operations, unlike its use
for operations under Sec. 91.175(l), does not result in operational
credit (e.g., a pilot using an EFVS on a Category II or III operation
cannot fly lower than a pilot not using an EFVS in a Category II or III
operation.)
The operational approval that permits an operator to conduct
Category II and/or Category III approach operations must include
specific provisions for the use of EFVS during such operations. EFVS
must first be demonstrated to be suitable during such operations.
Airborne systems used for Category II and III operations were first
certified to comply with airworthiness criteria found in AC 120-28D or
AC 120-29A, as applicable. EFVS changes the installed configuration of
those airborne systems, and there should be airworthiness
demonstrations to show that the new system configuration still complies
with the applicable criteria. The FAA anticipates that there will be
visibility conditions where ``flight visibility,'' but not ``enhanced
flight visibility,'' is lower than the prescribed approach minima. It
is important to recognize the differences between a Category II
approach and an instrument approach using an EFVS under Sec.
91.175(l), even when flown in such conditions. Category II approaches
require a runway facility that satisfies the Type II criteria found in
ICAO Annex 10. The Category II instrument approach procedure specifies
decision height and visibility minima that are less than for a Category
I ILS approach to the same runway. The airborne equipment must meet
specific performance and integrity criteria outlined in AC120-29A and
its Appendix 3.
Essentially, Category II and Category III operations depend on
improved flight path performance and integrity as mitigation for lower
visibility conditions. Instrument approach procedures other than
Category II or Category III that are based on compliance with Sec.
91.175 (l) and (m), use EFVS as an alternative means that would allow
the use of an EFVS to determine enhanced flight visibility and would
permit the descent and operation below the DH. The Category I ILS
instrument approach procedure, which specifies a decision height and
minimum visibility, is not changed when using EFVS in compliance with
the rule change proposed in the NPRM. Essentially, the rule permits
descent based on ``enhanced flight visibility'' rather than ``flight
visibility'' being no less than the visibility prescribed in the
instrument approach procedure. The FAA disagrees that an approach using
EFVS is the de facto equivalent of a Category II or Category III
approach.
Advisory Circular guidance for certification of EFVS, and perhaps
even a technical standard order (TSO), might be issued in future. In
the mean time, issue papers and special conditions may be used to
certify EFVS based on its ability to perform its intended function and
the required characteristics as specified in the rule, a system safety
assessment, and existing certification criteria for software,
programmed logic devices, head-up displays, and other criteria, as
applicable to the EFVS design. In addition to criteria contained in
issue papers from previous certifications, industry documents, such as
Society of Automotive Engineers (SAE) Aerospace Standard (AS) 8055 and
Aerospace Recommended Practices (ARP) 5288, provide a useful starting
point for guidance material.
The FAA will consider the commenter's proposed minimum software
design assurance level A for certain EFVS functions during the
certification process. The FAA requires a system safety analysis,
including a functional hazard assessment that will provide a basis for
the design assurance levels of software-based functions, in accordance
with well-established certification processes. As many commenters
stated, part 91 is not the
[[Page 1630]]
place for certification requirements. The FAA limits its list of
required features and characteristics of EFVS in Sec. 91.175 (m) to
the minimum needed to satisfy operational requirements.
IV.26. Compliance With Sec. 91.1039
Comment: A commenter states that it has a strong interest in the
NPRM's applicability to Sec. 91.1039 IFR takeoff, approach, and
landing minimums, under ``Subpart K--Fractional Ownership Operations''
as proposed on July 18, 2001 (66 FR 37520). This commenter believed
that the community regulated under that proposed subpart K would
achieve significant safety benefits and operational efficiencies given
access to the full use of EFVS.
FAA's response: The FAA agrees. The amendment to Sec. 91.175
applies to operators conducting operations under part 91 subpart K (see
final rule at 68 FR 54568). The requirements in Sec. 91.1039 will
supplement those in Sec. 91.175.
IV.27. Definitions--Italics and Capitalization
Comment: One commenter requested clarification of the italics and
capitalization in the definition of EFVS.
FAA's response: The definition of EFVS contains no italics or
capitalization, except for the title. The title was italicized in the
same format as all part 1 definitions.
IV.28. Definitions--Scope of Enhanced Flight Vision Systems
Comment: One commenter recommended broadening the definition of
EFVS and stated the definition of enhanced flight visibility is
unjustified and inappropriate. Also, the commenter said that it
unfairly targets or favors one technology and without more operating
experience could be unsafe.
FAA's response: The FAA disagrees with this comment because the
intent of this rule is to provide a basis for the use of imaging sensor
technologies that can provide a real time display of the external
scene. The FAA will ensure the safety of an EFVS system during the
certification process.
IV.29. Definitions--Examples of Enhanced Flight Vision Systems
Comment: A commenter recommended deleting examples of EFVS
technology listed in the definition of EFVS, because including those
examples would inhibit the development of new technologies due to a
lack of regulation and future certification guidelines.
FAA's response: The FAA disagrees with this comment. Simply listing
examples of current EFVS technology in the definition of EFVS does not
preclude the use of other EFVS technologies.
IV.30. Definitions--Enhanced Vision Systems
Comment: Several commenters suggested using the term enhanced
vision system (EVS) instead of EFVS because EVS is an industry-
recognized term.
FAA's response: The FAA considered the terminology to be used for
EFVS, including alternatives such as the commonly used ``enhanced
vision system.'' There are a variety of systems labeled EVS and a
number of EVS definitions which the FAA believes could be confused with
the system definition and operational concept found in Sec. 91.175 (l)
and (m). The FAA needed to define the term ``enhanced flight
visibility'' and the system that provides it, so it was logical to
label that system with a name that built on enhanced flight visibility;
hence ``enhanced flight vision system.'' To be clear that not all
systems now called EVS would necessarily be capable of supporting
compliance with Sec. 91.175 (l) and (m), the FAA will continue to use
the term EFVS.
IV.31. Definitions--Topography and Enhanced Flight Vision Systems
Comment: Another commenter recommended removing the term topography
from the definition of EFVS.
FAA's response: The FAA disagrees with this comment. The term
topography was included in the definition of EFVS to be clear that the
system would display objects on the ground and landscape.
IV.32. Synthetic Vision Systems
Comment: Several commenters suggested changing the definition of
synthetic vision. One commenter asked that the FAA begin to identify
the enabling benefits of lower-cost computer-generated SVS for use in
smaller general aviation airplanes, and to ensure that SVS operational
capabilities occur in concert with the development of SVS equipment.
FAA's response: As stated in the NPRM, synthetic vision system is
defined to distinguish it from enhanced flight vision system; this
rulemaking applies only to enhanced flight vision system. The FAA did
not propose the situation where SVS might be authorized in the future.
IV.33. Enhanced Ground Visibility Systems
Comment: One commenter suggested adding the term ``enhanced ground
visibility.'' The commenter proposed defining enhanced ground
visibility as the average forward horizontal distance, from the cockpit
of an aircraft on the ground, at which prominent topographical objects
or buildings may be clearly distinguished and identified by day or
night by a pilot using an EFVS.
FAA's response: The FAA disagrees because this is not within the
scope of this rulemaking.
IV.34. Straight-in Approaches
Comment: One commenter stated that the NPRM would allow EVS to be
used on all straight-in approaches. These are allowed to be up to +/-30
degrees to the runway centerline. TERPS allow the angular intercept to
be displaced from the threshold for Category I approaches. The vast
majority of HUD visual systems have only +/-15 degrees of visual (30
degrees total) of display capability. EVS as defined in the NPRM may
not be capable of even imaging or displaying the runway environment of
many ``straight-in'' approaches.
FAA's response: The rule is not limiting or predicated upon the
field-of-view from a specific system. The rule simply states that if
the pilot can see the required visual references at the DH or MDA using
the EFVS, then he or she can continue the approach. If the field-of-
view on the proposed system is limiting, the pilot would not be able to
see the required visual references and could not continue the approach
below the DH or MDA.
IV.35. Flight Visibility or Enhanced Flight Visibility
Comment: A commenter noted that the NPRM would require that the
pilot must deliberately choose which, differing rule--Sec. 91.175(c)
or Sec. 91.175(l)--he or she will use to conduct an approach. This
imposes upon each general aviation or commercial/transport pilot the
need to mentally maintain the differences between two highly similar
rules on an approach-by-approach basis. Further, the rules do not
specify if the pilot is free to switch between the requirements of the
two differing rules during the approach to his best advantage or if he
must choose a rule set before the approach and then stick with it
regardless of the advantage to switching to the other rule set.
FAA's response: This rule was written to parallel existing Sec.
91.175(c),
[[Page 1631]]
therefore, for a pilot to gain the benefit of using an EFVS, he or she
must know and comply with the different, but parallel requirements of
Sec. 91.175(l). If a pilot begins an approach using a certified EFVS
and the visual references using natural vision become more prominent,
the pilot may continue the approach by satisfying the requirements of
Sec. 91.175(c).
Conversely, if a pilot begins an approach using natural vision, and
the visual references using natural vision appear less prominent, the
pilot may continue the approach by satisfying the requirements of Sec.
91.175(l).
IV.36. Reduced Approach Minima
Comment: One commenter proposed an alternative revision of Sec.
91.175 and claimed that it updates certain outdated provisions and
provides a basis for approval of future system or capabilities that can
be shown to provide equivalent or better performance than currently
acceptable systems or procedures. The commenter noted that the
successful provisions of Sec. 91.175 were developed, used, and
improved over many years to achieve a high level of safety when
operating an aircraft during reduced visibility conditions.
Additionally, the commenter stated that current rules related to
instrument approach procedures implicitly allow (e.g., by use of
Administrator authorizations under Sec. 91.175(a) or provisions such
as Sec. 121.567 operations specifications) for the use of new
technologies such as enhanced flight vision systems, required
navigation performance, certain forms of GPS-related augmentation, or
visual reference enhancing sensors, without having to directly address
a specific performance standard for such authorizations.
FAA's response: The FAA disagrees with the commenter's proposed
rule amendment and believes it would be incorrect to predicate
authorization for EFVS to be used in lieu of the current provisions of
Sec. 91.175(c) based solely on the limited authority stated in Sec.
91.175(a) for the Administrator to authorize instrument approach
procedures other than those prescribed in part 97. The FAA believes it
is more appropriate and more helpful to the public to publish the
amended rule because it more clearly describes the requirements for
operations using the EFVS to achieve an equivalent level of safety to
the provisions of Sec. 91.175(c).
IV.37. Natural Vision
Comment: One commenter questioned the validity of comparisons,
stated in the NPRM, of EFVS imagery to natural vision for satisfying
the visual requirements for continuing the approach. In particular, the
commenter asked why the visual references as viewed in the EFVS imagery
(using an imaging sensor operating in either infrared (IR) sensor or
millimeter (mm) wave parts of the electromagnetic spectrum) may be any
less natural if displayed to the pilot in the visual part of the
spectrum.
FAA's response: The FAA believes the comparisons of EFVS imagery
and natural vision to be valid rationale for publishing the amended
rule. Section 91.175(l) provides an option to use EFVS to satisfy
visual requirements for the approach that are analogous to the time-
tested provisions of Sec. 91.175(c), and thereby makes operational
benefits available to those who wish to equip with an EFVS.
IV.38. AC 120-29A
Comment: Another commenter noted that AC 120-29A, section
4.3.4.4(b), Specified Visual Reference, provides some credit to HUD
synthetic symbology as supplemental information to external red lights.
The commenter suggested that in the future, when the combination of a
HUD and EFVS will be certified as an airborne equipment, it may be that
some other supplemental aids will be identified, and that criteria to
establish practicable minima (i.e., visibility prescribed) will have to
be defined.
FAA's response: AC 120-29A, paragraph 4.3.4.4, describes concepts
upon which FAA Order 8400.13a, Procedures for the Approval of Category
II Operations and Lower Than Standard Category I Operations on Type I
Facilities, is founded for approving Category I ILS operations with
lower than standard minima and Category II operations at Type I
facilities. Unlike the provisions of the amended rule, authorizations
based on FAA Order 8400.13a require, as a prerequisite, flight crew
members and installed airborne systems that are approved and authorized
for Category III operations. Unlike operations authorized per FAA Order
8400.13a, operations conducted under provisions of the amended rule do
not reduce the approach minima.
IV.39. Runway Environment as a Visual Reference
Comment: One commenter asked if the pilot can descend below basic
minimums (usually 200 feet) on a Category I glide slope beam, using
runway-environment cues obtained solely from the EFVS.
FAA's response: If the visual references of Sec. 91.175(l)(3), the
approach light system (if installed) or the runway threshold and the
touchdown zone of the intended runway, are distinctly visible and
identifiable to the pilot at the DH or MDA using an EFVS, the pilot can
continue the descent to an altitude of 100 feet above the touchdown
zone elevation. The pilot must then see, using natural vision, the
required visual references of Sec. 91.175(l)(4) that identify the
runway environment without reliance upon the EFVS to land the aircraft.
IV.40. Barometric Altitude
Comment: One commenter stated that no criteria are given on an
acceptable means to determine the altitude at 100 feet above the
touchdown zone elevation. Radar altitude may be inappropriate since
there are no controls on terrain prior to the runway threshold for
nonprecision approaches and not appropriate controls for Category I ILS
approaches.
FAA's response: The pilot may use the barometric altimeter to
determine when the airplane has reached 100 feet above the touchdown
zone elevation of the runway of intended landing.
IV.41. Reliance on EFVS
Comment: A commenter requested clarification of the words ``without
reliance on the EFVS'' as stated in Sec. 97.175(l)(4). Would this
require turning off the EFVS?
FAA's response: The rule does not require the EFVS to be ``turned
off.'' The HUD/EFVS displays aircraft performance and navigation
information, while the normal visual cues are being enhanced for
increased situational awareness and safety. However, the pilot cannot
rely on the EFVS to display the required visual references in Sec.
91.175(l)(4), once the pilot descends below 100 feet above the
touchdown zone elevation.
IV.42. Touchdown Zone Determination
Comment: One commenter stated that EFVS as defined by the rule is
not capable of allowing part 121 and part 135 operators to make the
determination to touchdown within the touchdown zone of the runway of
intended landing. HUD-style inertial flight path vector symbology can
be utilized to determine where current descent rates are taking the
aircraft, but they require that the EVS sensor provide indications as
to the beginning and end of the touchdown zone.
FAA's response: As is true today, parts 121 and 135 operators must
manage the descent rate so that the touchdown will occur within the
touchdown zone of the runway of intended landing. The FAA believes
[[Page 1632]]
that an EFVS can provide sufficient imagery so that the pilot can
define the touchdown zone. If the pilot does not have sufficient
required visual cues either with the EFVS display or looking out of the
window to satisfy this requirement, then a missed approach must be
executed.
IV.43. Training
IV.43.a. AFM & RFM Limitations
Comment: One commenter asked the FAA to consider removing the
reference in Sec. 91.175(l)(5)(iii) to compliance with the AFM and RFM
limitations section, because it is redundant to an existing rule.
Section 91.9 already requires that a pilot comply with the operating
limitations specified in the AFM or RFM. Restating it here might cause
part 121, part 125, and part 135 operators, listed in Sec.
91.175(l)(5)(i), to think they do not have to comply with the AFM
limitations.
FAA's response: The FAA agrees and has changed Sec.
91.175(l)(5)(iii) to delete references to the AFM and RFM. The
additional requirements of parts 121, 125 and 135 are addressed in each
of those respective parts and are mandated in the operator's operations
specifications. The operators, once certified, are required to comply
with the provisions of the operations specifications and all approved
or accepted training and/or checking programs. The operator is
responsible for the training and checking of each pilot using the EFVS
if authorized under the pertinent and applicable parts of the Code of
Federal Regulations. Operations conducted under part 91 do not require
training or checking on the EFVS, although pilots who operate EFVS
equipped aircraft are potentially subject to being checked on such EFVS
equipment during currency and proficiency checks of part 61.
IV.43.b. No Additional Training
Comment: A commenter noted that no additional training for the use
of EFVS should be required under part 61 for general aviation pilots
operating under part 91.
FAA's response: FAA agrees that a specific training requirement for
the use of EFVS for part 91 operators does not need to be added to the
rule. However, a Flight Standardization Board (FSB) did evaluate one
system and determined that additional crew training was required,
documented the required training in the FSB report and all pilots
operating aircraft subject to that FSB report with the FAA evaluated
EFVS system will have an operating limitation in the AFM requiring
pilot training.
IV.43.c. Additional Training and Proficiency
Comment: One commenter stated that the rule does not address part
61 as far as pilot training requirements, but does address parts 121,
125, and 135 and states that operations under 91 would be authorized.
The rule requires pilots to be proficient and qualified in accordance
with part 61. Part 61 covers basic instrument qualifications under
Sec. 61.57 and an additional requirement for Category II operations
under Sec. 61.67. The commenter suggested that additional training and
proficiency requirements for operations (involving) EFVS should be
established to ensure the same level of safety as for Category II
operations, since this new technology is going to allow pilots to
operate at lower than normal minimums.
FAA's response: The FAA believes that pilot training requirements
for applicants under the Airline Transport Pilot and Aircraft Type
Rating, Practical Test Standards for Airplane and Airline Transport
Pilot and Aircraft Type Rating, Practical Test Standards for Helicopter
should remain pilot certificate specific. Pilots obtaining certificates
under the provisions of part 61 are subject to testing and proficiency
checks under Sec. 61.58, may need to obtain training in order to pass
the check on all of the installed equipment on an aircraft, and must,
at the least, demonstrate proficiency in the use of the installed
equipment to the same standards required for the original issuance of
the certificate. Also, all pilots who conduct operations under part 91
must meet the currency requirement of Sec. 61.56, which may include
the aircraft and equipment. The FAA is not proposing to modify the
existing pilot requirements of part 61.
The FAA disagrees with the commenter's reasoning that additional
training and proficiency requirements are necessary for EFVS operations
because the new technology will enable pilots to operate at lower than
normal minimums. The use of EFVS does not reduce approach minimums;
EFVS is an alternate to the requirements of Sec. 91.175(c).
Part 61 does not require training prior to authorizing Category II/
III operations or other procedures beyond the initial pilot
certification process. Nor does the FAA believe that it is appropriate
to mandate training requirements beyond that of the initial
certification process or flight review process for operators under part
91 conducting standard instrument approach procedures.
IV.43.d. Crew Training
Comment: One commenter stated that due to the specifics of
interpreting an IR image, crew training will be an important issue and
needs to be carefully addressed. The commenter comments that specific
simulation models need to be defined as they exist for Category III HUD
landing system qualifications, and that typical and worst case
situations must be defined for simulator use (windshear, crosswind,
visibility, obstructions, etc.) in order to ensure that the crew can
reach an acceptable proficiency level with the system. Crew
qualification should be based on performance obtained in the simulator.
FAA's response: The FAA disagrees with limiting crew training to
the simulator. Holders of air carrier certificates and commercial
operator's certificates are held to higher standards and are therefore
required to provide FAA-approved training programs developed for the
type of operation to be conducted. Such programs, whether training or
checking and testing, may take advantage of any appropriate FSB Report
issued.
While the FSB Report is not regulatory in nature it provides the
FAA principal inspector with guidance as to the proper content,
duration, and intent of any training program submitted for approval or
acceptance in accordance with the operating rule. In addition,
facilities that provide training on behalf of manufacturers rely on
recommended training such as an FSB Report when developing training and
checking programs for their customers.
IV.44. Requirements for the Airplane Flight Manual (AFM)
Comment: One commenter stated that the operational limitations for
an EFVS should be included in the AFM and not included in a rule.
FAA's response: The FAA agrees with the commenter that some
operating limitations, in addition to those specified in this final
rule, may be placed in an AFM or RFM, depending on the certification
evaluation of a particular applicant's EFVS. The FAA disagrees that all
operating limitations should be specified in the AFM or RFM.
IV.45. Air Carrier Operations Specifications Requirements
Comment: One commenter stated that the NPRM includes a proposed
requirement to obtain operations specifications authorization for air
carriers (proposed Sec. 91.175(l)(6)). Operations specifications
approval is always required for decreased
[[Page 1633]]
minimums, but EFVS does not change the minimums. The EFVS allows the
pilot to visually acquire the cues specified in Sec. 91.175 to descend
below DH, but does not affect the minimums given on the approach
procedure. Therefore, operations specifications approval should not be
required. The requirement for operations specifications approval adds
an unwarranted financial burden on the operator, and may take a very
long time to achieve because most principal operations inspectors do
not have the background knowledge to make this evaluation. The FAA
certification pilots and engineers are required to accomplish extensive
testing to validate the EFVS. The commenter considers that there is no
reason to require an additional approval, beyond that achieved by STC.
FAA's response: The FAA agrees that use of EFVS does not change the
instrument approach minima. However, the FAA believes that Sec.
91.175(l)(6) should not be revised to incorporate the commenter's
recommendation. Part 119 and part 125 certificate holders and part 129
operations specifications holders that use a HUD today for the conduct
of instrument approach procedures require authorization in their
operations specifications. This authorization includes training on the
equipment and procedures to fly instrument approach procedures.
Likewise, the EFVS, which also includes a HUD, will require training in
the use of a HUD symbology and procedures developed by the operator for
the specific equipment being used. The FAA also does not agree that
this is an unwarranted financial burden on the operator or that
principal inspectors will not have the background or knowledge to
evaluate the air carrier's program. Principal inspectors routinely
authorize operations that require a HUD and in fact work directly with
the operator to develop these programs and procedures. To assist the
principal inspectors, the FAA will provide handbook guidance.
IV.46. Foreign Aircraft Certification
Comment: One commenter states that the proposed rule violated
existing bilateral agreements, and precludes the possibility of the FAA
ever accepting an EFVS approval by another authority through the
bilateral process without additional rulemaking. Another commenter
stated that this proposed rulemaking seems to introduce discrimination
towards non-U.S. manufacturers.
FAA's response: The intent of the rule, referenced in Sec.
91.175(l)(7), was to be fully consistent with the provisions of
existing bilateral agreements for aircraft certification. Under such an
agreement, a non-U.S. aviation authority may, on behalf of the FAA,
find compliance to FAA certification requirements. The FAA would
validate such findings and issue a U.S. type certificate (i.e., type
certificate, amended type certificate, or supplemental type
certificate, as applicable). U.S. type certificates would be available
for installation of non-U.S. manufactured EFVS, just as they are for
installation of other types of equipment today, whether manufactured in
the U.S. or not.
The FAA revises the language in Sec. 91.175(l)(7) to clarify that
the FAA does not discriminate against foreign operators or non-U.S.
manufacturers.
IV.47. Equipment Requirements for Subpart C
Comment: One commenter stated that the proposed rulemaking did not
clearly define equipment requirements, and that there was no proposed
rulemaking regarding EFVS in subpart C of part 91. The commenter asked
the FAA to clarify EFVS equipment requirements and establish an EFVS
TSO that clarifies the design requirements for enhanced flight vision
sensors or equipment, excluding the HUD.
FAA's response: The FAA disagrees that a requirement for EFVS
equipment should be added to part 91 subpart C. The rule allows for the
use of an EFVS to determine ``enhanced flight visibility'' in lieu of
``flight visibility.'' An EFVS is not required equipment, except for
those operators choosing to use this alternative method of operation
below DH or MDA.
Advisory Circular guidance for certification of EFVS, and perhaps
even a TSO, might be issued in the future. In the meantime issue papers
and special conditions may be used to certify EFVS based on its ability
to perform its intended function and the required characteristics as
specified in the rule, a system safety assessment, and existing
certification criteria for software, programmed logic devices, head-up
displays, and other criteria, as applicable to the EFVS design. In
addition to criteria contained in issue papers from previous
certifications, industry documents, such as Society of Automotive
Engineers (SAE) Aerospace Standard (AS) 8055 and Aerospace Recommended
Practices (ARP) 5288 provide a useful starting point.
IV.48. Clarification on Maneuvering
Comment: A commenter requested that the FAA clarify the meaning of
the phrase ``which is suitable for maneuvering the aircraft'' as stated
in Sec. 91.175(l)(7).
FAA's response: The FAA means that the EFVS display, because it is
being used as the pilot's primary flight reference during the approach,
at least down to 100 feet above the touchdown zone elevation, needs to
provide effective visual feedback to the pilot for manual control of
the airplane. In particular, the alignment and motion of the EFVS
imagery, attitude and guidance symbology must faithfully represent
airplane motions, without significant jitter, jerkiness, or latency
(i.e., display lag, slow update rate) that would adversely affect the
pilot's ability to manually control the airplane with satisfactory
precision, stability and workload. In addition to EFVS display
dynamics, many other factors such as field of view, control of display
luminance, clutter, and display blooming could significantly degrade
pilot performance and workload while manually controlling the airplane
in the approach.
IV.49. Certification of an EFVS
Comment: Several commenters noted that the EFVS features and
characteristics specified in the proposed Sec. 91.175(m) were
certification requirements, not operational requirements, and should be
deleted from the rule and moved to parts 23 and 25 and/or associated
advisory material. Another commenter said that the specified
characteristics are not quantified and lack detail without reference to
a Minimum Operational Performance Specification (MOPS) or some other
technical standard. Certification requirements, processes, and
regulations need to be developed and issued expeditiously.
FAA's Response: The FAA believes that in order to safely and
effectively perform approach operations under the provisions of Sec.
91.175(l), there are certain essential characteristics and features
that must comprise the EFVS. Therefore, the FAA believes this list
specified in paragraph (m) constitute operational requirements. The
items in this list were deliberately stated in general terms, well
enough to capture the essential requirements but without over-
specifying the system design to permit as much design flexibility as
possible.
The operationally essential features of the EFVS are that the image
and spatially referenced flight symbology is displayed so that they are
aligned with and scaled to the external view (conformally) on a HUD
with essential flight instrument information. The image must be
conformal because it
[[Page 1634]]
provides an alternative, enhanced forward view that could be used in
lieu of flight visibility to meet the prescribed visibility
requirements.
The imagery must be displayed on a HUD because the FAA believes
that the safety of an approach operation conducted under Sec.
91.175(l) depends on the pilot looking forward along the flight path
(i.e., looking at and through the imagery to the out-of-the window
view) to readily enable a transition from reliance on the EFVS imagery
above 100 feet height above the touchdown zone elevation to reliance on
the out-the-window view without reliance on EFVS. The FAA believes that
if the pilot must scan up and down between a head down display of the
image and the out-the-window view, then the transition would be
hindered by the delay of repeatedly re-focusing from one view to the
other.
The imagery must be displayed with essential flight instrument
information because the FAA believes that once the EFVS is being relied
on for descent and operation below DH, or MDA, it should become the de
facto primary flight reference. The pilot requires continuous awareness
of the flight information while using the EFVS imagery. This awareness
would be unsatisfactorily degraded by repeated scanning from head up,
to head down, and back.
IV.50. Performance-Based Advisory Materials
Comment: Several commenters said that an advisory circular or
advisory material is needed to support the rule, but that the
development of new advisory material need not delay adoption of a
suitable enhanced vision system rule. Another commenter recommended the
FAA begin work on an AC to establish airborne equipment certification
standards, training, and AFM endorsements that ensure that the items
referenced in Sec. 91.175 are distinctly visible with the EVS.
Another commenter requested that the FAA draft specific EVS
technical and system design language, along with suggested
certification methodologies and place in appropriate advisory material.
Still another commenter saw advisory material as the means for
certification through performance standards. This commenter noted that
the proposed Sec. 91.175(m)(1) of the rule, which addresses features
and characteristics, states: ``An electronic means to provide a display
of the forward external scene topography (natural or manmade features
of a place or region especially in a way to show their relative
positions and elevation) through the use of imaging sensors, such as a
forward looking infrared, millimeter wave radiometry, millimeter wave
radar, and low-light level image intensifying.'' Similar wording also
appears in the EFVS definition in part 1. Neither the rule nor the
definition should cite specific current-generation technology, but
rather should reflect a performance or implementation requirement that
can be further developed in advisory material. For example, the sensor-
based imaging elements of the EFVS shall be appropriately located on
the aircraft, shall employ a sensor technology appropriate to the
intended function, and the combination of the sensor and HUD shall
provide resolution and other system attributes coincident with the
generation of a high-quality conformal image. Certification criteria
for future EFVS should be the subject of an AC. As an example, the use
of a HUD system is required in the proposed rule. The commenter
believed this language may not stand the test of time and therefore
requests that the language be changed to reflect the use of a display
and symbology set certified for the intended function.
FAA's response: The FAA believes that Sec. 91.175(l) and (m)
provide operational requirements that are not specific to a particular
technology design. The FAA agrees that advisory material for
certification of EFVS will be useful, but not that such material should
replace Sec. 91.175(m), which specifies essential operational
requirements for EFVS. At this time, until more experience is gained
with the potential variations of EFVS designs, it is premature to
establish such guidance. Until such guidance is available, issue papers
and special conditions may be used to certify EFVS based on its ability
to perform its intended function and required characteristics as
specified in the rule, a system safety assessment, and existing
certification criteria for software, programmed logic devices, head-up
displays, and other criteria, as applicable to the EFVS design. In
addition to criteria contained in issue papers from previous
certifications, industry documents, such as Society of Automotive
Engineers (SAE) Aerospace Standard (AS) 8055 and Aerospace Recommended
Practices (ARP) 5288 provide a useful starting point. The FAA expects
that a working committee of the Society of Automotive Engineers (SAE)
or similar group will undertake further efforts to develop industry
certification standards for EFVS that could support EFVS advisory
material.
The FAA believes it is necessary to include Sec. 91.175(m) in the
rule because the alternative means outlined in Sec. 91.175(l) for
descent and operation below DH or MDA requires an EFVS with such
features and characteristics. Other technology solutions for conducting
low visibility approach and landing operations, such as SVS, would
require a different operational.
IV.51. Display Comments
IV.51.a. Head-Up or Head-Down Displays
Comment: There were several comments stating that the FAA should
allow both a head-up display or a head-down display for EFVS in
paragraph (m) and should permit alternate display locations. One
commenter suggested revising paragraph (m)(2) to say, ``The EFVS sensor
imagery and aircraft flight symbology (i.e., at least airspeed,
vertical speed, aircraft attitude, heading, altitude) are presented on
head-up display or other certified display within the pilot's primary
field of view and clearly visible to the pilot flying in his or her
normal position and line of vision and looking forward along the flight
path.'' This commenter also stated that when transitioning from
``enhanced flight visibility'' to ``flight visibility'' the pilot would
only make a slight change in focus, very similar to the transition
taking place when conducting currently regulated approaches down to low
minimums.
FAA's response: The FAA disagrees with the recommendation to permit
any certified head-down display for EFVS.
The rule requires that EFVS include a head-up display rather than
the alternative of a head-down display because the pilot is conducting
an instrument approach procedure in lower visibility conditions, but
with no change in the prescribed instrument approach minima and must
accomplish several visually-related judgments and control tasks in
quick succession. While the regulatory requirements for the use of EFVS
are analogous to the conventional requirements for descent and
operation below DH or MDA, the pilot needs to use the imagery, the
flight reference information, and eventually the outside view, at the
same time. The pilot must be able to look for the outside visual
references in the same location as they appear in the EFVS image and
readily see them as soon as visibility conditions permit, without any
delays or distraction due to multiple head-up/head-down transitions.
When scanning between the head-up and head-down views, it takes
additional time for the pilot to reacquire the information in each view
and for the pilot's eyes to readjust for differences in light level and
changes in focus between
[[Page 1635]]
optical infinity and the distance to the instrument panel (on the order
of 24 inches). Repeated scanning between the head-up and head-down
views would be distracting, increase pilot workload and potentially
degrade path performance during a critical phase of flight.
These effects are avoided by displaying the EFVS imagery and flight
information on the HUD. Between the DH or MDA and 100 feet, the pilot
will be able to look for the outside visual references in the same
location as they appear in the EFVS image and readily see them as soon
as visibility conditions permit, without any delays or distraction due
to multiple head-up/head-down transitions and without interruption of
the view of essential flight information.
IV.51.b. Head-Up Display
Comment: One commenter stated that HUD presentation and modern
display symbols including flight path vector, reference flight path
angle, and horizon marks (and ideally airspeed error and trend) have
been repeatedly shown to dramatically decrease workload and increase
landing accuracy when overlaying the actual runway environment.
FAA's response: The FAA agrees with the commenter that additional
head-up display symbology should be required for the EFVS. Section
91.175(m)(2) is therefore amended to require a FPV and a flight path
angle reference cue. Because this rulemaking has created an exception
to the time-tested existing safety standards in Sec. 91.175(c), it is
within the scope of the notice to tighten the conditions for such an
exception at the final rule stage when, as here, potential safety
problems and solutions are identified by commenters. In other words,
the exception language as originally proposed would not have required
FPV as a condition for the EFVS to be used, adding FPV as a required
feature narrows the proposed exception and thus is within the scope of
the proposed exceptions.
IV.51.c. Guidance, Flight Path Vector (FPV), and Other Symbology
Comment: Several commenters stated that the rule should
specifically require additional items of flight information, including
the flight path, guidance, conformal flight path vector (FPV) and cues
for energy state control.
One commenter stated that the rule is not clear about the need for
guidance in the EFVS display and recommends that the rule be amended to
include a requirement for flight director or some form of command
guidance, conformal presentation of FPV, and cues for energy state
control.
In a related comment, another person stated that the FAA should
continue to require the use of HUD, that ILS guidance should also be
displayed on the HUD, and that the EFVS should have a head-up guidance
system, not just a HUD.
Similarly, other commenters stated that the FAA omitted the FPV, an
important symbology cue, in its list of required features and
characteristics of EFVS in paragraph (m). This symbology cue combines
drift angle and flight path angle to show where the aircraft is
actually going (also known as velocity vector) as opposed to where the
nose is pointed (longitudinal axis).
FAA's response: The FAA agrees with the comments that the rule
should be revised to require EFVS to display flight path (i.e., the
intended approach path as shown by lateral and vertical path deviation
indications), command guidance, a conformal FPV, and a flight path
angle reference cue. The FAA does not agree that the rule should be
revised to mandate other suggested symbology cues, such as cues for
energy state control, airspeed error and trend.
The FAA has revised the rule to require that the EFVS display
lateral and vertical approach path deviation indications (e.g.,
localizer, glideslope or course deviation indications (CDI)) and
command guidance (e.g., repeat display of head down flight director, or
HUD unique command guidance cue) as appropriate for the kind of
approach to be flown. The rule requires approach path deviations
because they are essential to conduct the approach and the pilot must
not be required to scan head down for the information. The rule
requires command guidance because, when available and appropriate for
the approach being flown, it reduces pilot workload, increases path
tracking performance, and was found essential for ILS approaches during
proof of concept evaluation of a previously certified enhanced vision
system. For types of approaches without a vertical navigation aid,
(e.g., localizer-only, or VHF omni-range station (VOR)), neither
vertical path deviation indications nor vertical guidance is required.
The FAA believes that the addition of a FPV and a flight path angle
reference cue provides effective tools to monitor and maintain a safe
vertical path from the DH/MDA to the desired touchdown point on the
runway. These changes are within the scope of the notice because in
proposed Sec. 91.175(m)(2) the FAA listed broad examples of the types
of flight symbology that would be required for safety purposes. The
items listed in Sec. 91.175(m)(2) were intended to be the minimum
flight symbology features on the HUD. The FAA is adding similar flight
symbology requirements to the final rule. By adding these additional
required features, the FAA is narrowing the circumstances under which
an EFVS could be used as an exception to the existing standards in
Sec. 91.175(c).
The rule does not explicitly specify other flight symbology cues,
such as those recommended by the commenters, because the FAA does not
have sufficient data to mandate them unconditionally. Such cues have
been essential features of previously approved HUD landing guidance
systems, but the intended function of these systems (e.g., Category III
landings) is different from EFVS, which is used to satisfy Sec.
91.175(l). Nevertheless, the FAA recognizes that such cues have been
found to enhance pilot performance, reduce workload, and believes they
might mitigate characteristics of EFVS imagery, compared to natural
vision in visual meteorological conditions (VMC), that are significant
for maneuvering the airplane. The FAA believes that the entire EFVS,
which includes the image, flight information and graphic symbology, not
just the imagery alone, must be suitable for maneuvering the airplane.
The FAA will evaluate each EFVS, including the symbology cues, for its
ability to satisfy the operational and safety objectives of the rule,
including its suitability for maneuvering the airplane. Based on
products already certified, the FAA anticipates that most, if not all
EFVS designs would include such features anyway.
IV.51.d. EFVS for Situational Awareness
Comment: One commenter stated that the FAA should not preclude the
use of EFVS for situational awareness.
FAA's response: This rule addresses only EFVS used to permit
descent and operation below the DH or MDA, when flight visibility
minima are not met.
IV.51.e. Design Eye Position
Comment: One commenter stated that a pilot's normal seating
position may not coincide with the design eye point, the position at
which the cockpit equipment was designed and certified. The commenter
stated that the position from which the pilot views the EFVS HUD is
critical to clearly seeing the EFVS imagery and flight symbology and
recommended that Sec. 91.175(m)(2) be revised to read: ``The EFVS
sensor imagery and aircraft flight symbology (i.e., at least airspeed,
vertical speed, aircraft attitude, heading, altitude) are presented on
a head-up display so that
[[Page 1636]]
they are clearly visible to the pilot viewing from the design eye
position and looking forward along the flight path.''
FAA's response: The FAA agrees with the commenter that the position
from which the pilot views the EFVS HUD is significant. The most
significant effect of a displacement from design eye position is that
some displayed information may not be visible to the pilot. For
certification of head-up displays, the FAA uses criteria described in
AC 25.773-1 (Pilot compartment view design considerations) and an FAA
issue paper titled ``Head-up display (HUD) installation, system design
policy and guidance,'' which will also be applied to EFVS, that
concerns variations of the pilot's viewpoint that constitute what has
been called the ``head motion box.'' This head motion box has minimum
dimensions in three axes and when the pilot's eyes view the HUD while
located in this volume, all essential information must be visible in
the HUD. The FAA agrees with the intent of the commenter's
recommendation, but believes that the recommended revision is not
necessary, because current HUD certification criteria will be applied
to EFVS and if the essential information is not clearly visible from
the design eye point, the EFVS could not perform its intended function.
IV.51.f. Display Conformality and Parallax Errors
Comment: One commenter noted that there is no requirement in Sec.
91.175 (m) regarding where the EFVS sensor is installed on the
airplane. The commenter stated that it is of the utmost importance that
EFVS imagery is displayed conformally with the outside view and that
parallax error must be very small, as it is with currently-certified
HUD guidance systems. The commenter recommended that the FAA revise the
rule to add a requirement that the EFVS sensor be installed in a
location such that the image is conformal to the outside view with no
more than 4 milliradians (mrad) of parallax error.
FAA's response: The FAA agrees with the commenter that the EFVS HUD
display must be conformal and that excessive parallax error, due to the
displacement of the sensor location from the pilot's line of sight,
would not be acceptable. Parallax is one error source that degrades
conformality. In fact, all HUD's currently certified for approach and
landing operations, with and without imagery, have this design feature.
Therefore, the FAA revised Sec. 91.175 (m)(2) to require that the EFVS
imagery, attitude symbology, FPV and other cues referenced in the
imagery and outside view must be presented aligned with, and scaled to,
the external view. This change is within the scope of the rulemaking
because an identified shortcoming in the draft exception (i.e., Sec.
91.175(l)), to the longstanding Sec. 91.175(c) standard, is being
corrected by narrowing the kinds of devices that would meet the
exception criteria.
As the commenter stated, conformality of the image and any
associated symbology means, that the angular orientation and scale
match the external view. Objects visible both in the image and out the
window would line up exactly when viewed by the pilot in the normal
seated position (i.e., at the design eye point). As the runway
threshold, approach light system, and so forth come into view out the
window, they would show up in the same location as they already appear
in the EFVS image.
This operational rule will not quantitatively specify the maximum
parallax (i.e., alignment) error, because the error can vary with
distance (i.e., more angular error at short distances) and an
acceptable limit may depend on the intended function. The amount of
parallax error that is acceptable for an approach with a transition to
outside visual cues no lower than 100 feet above the touchdown zone
elevation might differ from what is needed for a landing system.
Industry standards, for example Society of Automotive Engineers (SAE)
Aerospace Standard AS8055 ``Minimum Performance Standards for Head-Up
Display (HUD),'' contain different values than those recommended by the
commenter.
During EFVS certification, the FAA will evaluate the display to
determine that the display is sufficiently conformal to the outside
view for its intended function, and that parallax error, if any, is not
excessive or misleading to the pilot.
Some information displayed in the HUD is not ``spatially
referenced'' and therefore does not need to be conformal. For example,
airspeed, vertical speed, altitude and some other data can be shown in
a variety of non-conformal formats, such as linear tapes and round
dials. Both conformal and non-conformal heading formats have been found
acceptable.
IV.51.g. Power System for an EFVS
Comment: One commenter stated that in case of a single failure
between 200 feet and l00 feet (engine or generator), a total loss of
enhanced vision would occur while the pilot most needs the EFVS to
maintain clearance with obstacles and to maintain runway alignment. The
commenter proposed that the rule should specify that the EFVS design
would guarantee the segregation between EFVS failures and failures
affecting aircraft path control and performance (ILS and HUD should not
be powered by the same electrical source as the EFVS for instance).
FAA's response: The FAA disagrees that this requirement should be
added to the operational rule. In cases where the EFVS fails between
the decision height and 100 feet above the touchdown zone elevation,
the rule, Sec. 91.175(e), requires that a missed approach be executed
if the requirements of (c) or (l) are not met. However, airworthiness
certification requirements for EFVS system architecture, redundancy and
independence of power supplies may result from compliance with the
system safety requirements (e.g., Sec. 23.1309, Sec. 25.1309, etc.).
IV.51.h. Independent Displays
Comment: One commenter requested clarification as to whether the
HUD must be independent of the head-down primary instruments.
FAA's response: Flight information (e.g., airspeed, altitude,
direction, attitude, path deviation) displayed on a pilot's EFVS HUD
does not need to be independent from the flight information displayed
on the pilot's head down primary flight references. Based on past
experience with HUD's approved as flight display for Category II and
Category III approach operations, this independence is not necessary.
However, as the certification rules require, the pilot's and co-pilot's
displays of flight information must be independent.
IV.52. Comments on Economic Evaluation
Comment: A commenter stated that the NPRM could create significant
unnecessary cost obstacles for both operators and manufacturers in the
United States by inappropriately and unfairly favoring technology that
is not mature, may not work, and may not be safe, compared with other
proven technologies. This situation has significant indirect
competitive costs, design costs, liability costs, and aircraft
operating penalty costs, which are not addressed by the NPRM.
FAA's response: The FAA disagrees. Because the rule is optional,
the FAA believes that the available technology should be allowed,
especially when it can enhance safety during low visibility conditions.
The FAA disagrees with the statement that this technology is unsafe
[[Page 1637]]
when used in accordance with the operating rules adopted today.
V. Contact With Aircraft Manufacturer for Confirmation of Performance
Capabilities
During the comment period, several FAA employees worked with one
aircraft manufacturer to evaluate the operational and technical
performance in the use of an EVS-equipped aircraft and simulator
system. This was necessary to confirm performance and limitations of
this technology in an operational environment.
VI. Differences Between the NPRM and Final Rule
As discussed under ``III. Related Rulemaking Actions,'' the FAA
included some terminology in the EFVS NPRM that had been proposed
earlier in the RNAV NPRM. Because, as of the issuance of this final
rule, the RNAV rulemaking action has not been completed, those proposed
changes are not being adopted. Specifically those proposed changes are
as follows.
In Sec. Sec. 91.175(c), 121.651(c) and (d), 125.381(c)(2), and
135.225(c)(3)(ii) the terms ``DA'' and ``DA/DH'' are not adopted in
this final rule. Therefore, all proposed references to ``DA'' and ``DA/
DH'' read ``DH.''
In Sec. Sec. 125.381(c)(1)(i) and 135.225(c)(1)(i) the words
``precision approaches'' are replaced with the abbreviation ``ILS.''
In Sec. 121.651(d), the word ``person'' is replaced by the word
``pilot.'' Also, the proposed change replacing the words ``an
instrument approach procedure other than a Category II or Category
III'' with ``a Category I precision approach'' is not adopted. In
addition, the proposed change replacing the words ``a operative ILS and
an operative PAR, and both'' with ``an operative PAR and another
operative precision instrument approach system, and both the PAR and
the precision approach'' is not adopted.
In Sec. Sec. 125.381(c)(1)(i) and 135.225(c)(1)(i) the term
``APV'' is not adopted in this final rule. Therefore, all proposed uses
of the term APV are deleted.
In addition, as a result of comments received, the FAA revises the
final rule as follows:
Category I operations--Section 91.175(l) is amended to include in
the rule text that this exception only applies to a ``* * * straight-in
instrument approach procedures other than Category II or Category III *
* *.''
Visual references--Under Sec. 91.175 (l)(3) of this final rule,
the visual references that the pilot can use at the DH or MDA to
continue the approach are clarified such that ``runway threshold and
the touchdown zone,'' as proposed in the NPRM, includes the approach
light system, if installed, or both the runway threshold and the
touchdown zone. This is discussed in detail under ``IV.3. Visual cues
(visual references)'' above. Combined, these references form a pattern
of recognition whereby the pilot may safely continue the descent to 100
feet above the touchdown zone elevation.
Qualification requirement--Section 91.175(l)(5) is revised to
change the qualification requirement to one of currency and to delete
reference to the limitations specified in the Airplane or Rotorcraft
Flight Manual.
Additional operational requirements--Section 91.175(m)(2) is
revised to include the additional operational requirements of command
guidance, path deviation indications, and flight path vector, flight
path angle reference cue to be displayed on the HUD. This change
narrows the scope of acceptable EFVSs by stating only those systems
that have these additional features will be permitted to operate under
Sec. 91.175(l).
EFVS display--Section 91.175 (m)(2)(i) is added to include the
additional operational requirement that the EFVS imagery and external
scene topography must be presented so that they are aligned with and
scaled to the external view. The FAA is also adding (m)(2)(ii) to
specify the essential features and intended function of the ``flight
path angle reference cue.'' In order to perform its intended function,
the cue needs to be set by the pilot to the desired value for the
approach, the pilot needs to see the cue in the context of pitch scale
to verify that it is correctly set, and it needs to be shaped and
located so as to allow the pilot to monitor the airplane's vertical
path. This is a descending path along the selected glide path angle and
is anchored to the desired touchdown point. To accommodate these
changes, paragraph (m)(3) is redesignated as (m)(2)(iii); paragraph
(m)(4) is redesignated as (m)(3); and (m)(5) is redesignated as (m)(4).
Topographical features--The FAA is amending Sec. 91.175 (m)(1) to
state that an EFVS must be able to display topographical features of
the airport environment. It is not the FAA's intent to require an EFVS
to detect all obstacles to ensure obstacle clearance in the visual
portion of the final approach segment.
VII. Discussion of the Final Rule
Possible operational benefits--This final rule will not require the
use of an EFVS. However, using an EFVS would allow operations in
reduced visibility conditions that would not otherwise be possible.
Category I operations--This final rule will retain the existing
straight-in-landing instrument approach minima for other than a
Category II or III approach, and will authorize the pilot to use FAA-
certified EFVS imaging-sensor technologies to determine enhanced flight
visibility. This final rule will allow a pilot to fly straight-in-
landing instrument approach procedures other than Category II and III
procedures and descend below the DH or MDA using an EFVS.
Category II and Category III ILS approach procedures--The final
rule does not prohibit the use of an EFVS for Category II and III ILS
approach procedures. The use of EFVS during Category II or Category III
operations must be specifically authorized by the Administrator. Any
future proposed enhanced flight vision systems for these approaches
would have to comply with the more stringent reliability, redundancy,
other criteria as discussed in the FAA's response to comments and as
prescribed in applicable sections of 14 CFR and applicable advisory
circulars. But the use of EFVS in Category II or III ILS approaches
does not lower minimums that would otherwise apply for aircraft not
equipped with EFVS conducting Category II or III ILS approaches.
Visual references--Section 91.175 (c)(3) lists ten visual
references, of which only one is required for the pilot to descend
below the DH or MDA. The visual references are: (1) The approach light
system, (2) threshold, (3) threshold markings, (4) threshold lights,
(5) runway end identifier lights, (6) visual glideslope indicator, (7)
touchdown zone or touch down zone markings, (8) touchdown zone lights,
(9) runway or runway markings, and (10) the runway lights identifying
the approach end of the runway. If the approach light system is used as
the reference, the pilot may not descend below 100 feet above the
touchdown zone elevation unless the red terminating bars or the red
side row bars are also distinctly visible and identifiable. As a
parallel, under paragraph (l)(3), the final rule states that, when
using an EFVS, the approach light system (if installed), or the runway
threshold (lights or markings), and the runway touchdown zone (lights
or markings) would have to be distinctly visible and identifiable to
the pilot before descending below the DH or MDA for the pilot to
continue the approach. See the discussion under
[[Page 1638]]
``IV.3. Visual cues (visual references)'' above.
Because the imaging-sensor technologies may not sense or display
all of the identifying features of the visual references (e.g., may not
distinguish colors of lights), the FAA in this final rule is clarifying
the visual references listed in Sec. 91.175(l)(3), as discussed under
``IV.3. Visual cues (visual references)'' above. Taken together, these
visual references form a pattern of recognition for the pilot to safely
continue the approach to 100 feet. At 100 feet above the touchdown zone
elevation and below, there would have to be sufficient flight
visibility (without reliance on an EFVS) for the lights or markings of
the threshold; or the lights or markings of the touchdown zone of the
intended runway to be distinctly visible and identifiable to the pilot
to continue to a landing.
Pilot qualifications--To use the EFVS equipment while conducting an
instrument approach procedure under this final rule, the pilot(s) must
be current and proficient in accordance with existing applicable
requirements in part 61, 121, 125 or 135. Each foreign pilot would have
to be qualified in accordance with the requirements of the operator's
State civil aviation authority. Foreign air carriers will be required
to comply with this rule and their operations specifications. For all
operators, this will include knowledge of the EFVS requirements,
operational procedures, and limitations as prescribed in the approved
Airplane or Rotorcraft Flight Manual for the specific system.
Certification process--An EFVS used under this final rule would
have to provide the pilot with sufficient guidance and visual cues so
that the pilot could manually maneuver the aircraft to a landing on the
intended runway. The sensor image alone may not be suitable to maneuver
the aircraft. For the pilot(s) to maximize situational awareness while
maneuvering the aircraft in the visual segment of the instrument
approach procedure, at low altitudes and reduced visibility conditions,
the FAA requires that several key components be provided by an EFVS to
provide an adequate level of safety. The EFVS sensor imagery must be
presented on a HUD that is centrally located in the pilot's primary
field of view and in the pilot's line of vision along the flight path.
The imagery must be real-time, independent of the navigation solution
derived from the aircraft avionics, and must be clearly displayed so
that it does not adversely obscure the pilot field of view through the
cockpit window.
Aircraft flight symbology, such as airspeed, vertical speed,
attitude, heading, altitude, command guidance (e.g., repeat display of
head down flight director, or HUD unique command guidance cue) as
appropriate for the kind of approach to be flown, and lateral and
vertical approach path deviation indications (e.g., localizer,
glideslope or course deviation indications (CDI)) must be provided. A
flight path angle reference cue and FPV also must be displayed on the
HUD and be clearly visible so that the pilot can monitor and maintain a
safe vertical path from the DH/MDA to the desired touchdown point on
the runway.
The displayed sensor imagery and aircraft symbology may not
adversely obstruct the pilot's vision looking through the aircraft's
forward windshield. The EFVS imagery, attitude symbology, FPV and other
cues which are referenced to the imagery and outside view must be
presented so that they are aligned with and scaled to the external
view.
The FAA will conduct the certification and evaluation process in
accordance with published guidance and current policy. The FAA will
also evaluate the capabilities, operational procedures, training and
limitations for the specific system as it is designed and flight-
tested. In all cases, the applicant for an airworthiness type design
will provide the FAA's Aircraft Certification Office (ACO) with a
certification plan. The FAA will evaluate the plan to determine if it
is addressed by current regulations or if special conditions would have
to be established for the certification. The EFVS will be evaluated in
an operational context to determine if the system provides an
equivalent level of safety when in operation compared to the present
rules. The operator of a foreign-registered aircraft must comply with
all of the applicable EFVS requirements of this rule.
VIII. Paperwork Reduction Act
The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires
that the FAA consider the impact of paperwork and other information
collection burdens imposed on the public. The FAA has determined that
there are no new information collection requirements associated with
this final rule.
IX. International Compatibility
In keeping with United States obligations under the Convention on
International Civil Aviation, it is the FAA's policy to comply with
International Civil Aviation Organization (ICAO) Standards and
Recommended Practices to the maximum extent practicable. The FAA has
determined that there are no ICAO Standards and Recommended Practices
that corresponded to these regulations.
X. Economic Evaluation
Changes to regulations must undergo several economic analyses.
First, Executive Order 12866 directs each Federal agency proposing or
adopting a regulation to only upon a reasoned determination that the
benefits of the intended regulation justify its costs. Second, the
Regulatory Flexibility Act of 1980 requires agencies to analyze the
economic impact of the regulatory changes on small entities. Third, the
Trade Agreements Act (19 U.S.C. 2531-2533) prohibits agencies from
setting standards that create unnecessary obstacles to the foreign
commerce of the United States. In developing U.S. standards, the Trade
Agreements Act requires agencies to consider international standards
and, where appropriate, as the basis of U.S. standards. Fourth, the
Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires agencies
to prepare a written assessment of the costs, benefits, and other
effects of proposed or final rules that include a Federal mandate
likely to result in the expenditure by State, local, or tribal
governments, in the aggregate, or by the private sector, of $100
million or more annually (adjusted for inflation).
In conducting these analyses, FAA has determined that this rule:
(1) Has benefits that justify its costs, is not a ``significant
regulatory action'' as defined in section 3(f) of Executive Order
12866, and is not ``significant'' as defined in DOT's Regulatory
Policies and Procedures; (2) will not have a significant economic
impact on a substantial number of small entities; (3) will not create
barriers to international trade; and (4) does not impose an unfunded
mandate on state, local, or tribal governments, or on the private
sector.
For regulations with an expected minimal impact the above-specified
analyses are not required. The Department of Transportation Order DOT
2100.5 prescribes policies and procedures for simplification, analysis,
and review or regulations. If it is determined that the expected impact
is so minimal that the proposal does not warrant a full evaluation, a
statement to that effect and the basis for it is included in proposed
regulation.
This rule will allow, but does not require, operators to use an
enhanced flight vision system on board their
[[Page 1639]]
aircraft. Therefore, this final rule will not impose any cost on any
operator. As discussed above under ``II. Discussion of the Proposed
Rule,'' the FAA believes that this final rule will provide operational
benefits and improve the level of safety.
XI. Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (RFA) establishes ``as a
principle of regulatory issuance that agencies shall endeavor,
consistent with the objective of the rule and of applicable statutes,
to fit regulatory and informational requirements to the scale of the
business, organizations, and governmental jurisdictions subject to
regulation.'' To achieve that principle, the RFA requires agencies to
solicit and consider flexible regulatory proposals and to explain the
rationale for their actions. The RFA covers a wide-range of small
entities, including small businesses, not-for-profit organizations and
small governmental jurisdictions.
Agencies must perform a review to determine whether a proposed or
final rule will have a significant impact on a substantial number of
small entities. If the determination is that it will, the agency must
prepare a regulatory flexibility analysis as described in the RFA.
However, if an agency determines that a proposed or final rule is
not expected to have a significant economic impact on a substantial
number of small entities, section 605(b) of the RFA provides that the
head of the agency may so certify and a regulatory flexibility analysis
is not required. The certification must include a statement providing
the factual basis for this determination, and the reasoning should be
clear.
The FAA certifies that this rule will not have a significant
economic impact on a substantial number of small entities. This
rulemaking will allow the operators the option of using an EFVS but the
use of such a system is not mandated. Therefore, this rulemaking will
not impose any cost on any operators
XII. International Trade Impact Analysis
The Trade Agreement Act of 1979 prohibits Federal agencies from
establishing any standards or engaging in related activities that
create unnecessary obstacles to the foreign commerce of the United
States. Legitimate domestic objectives, such as safety, are not
considered unnecessary obstacles. The statute also requires
consideration of international standards and, where appropriate, that
they be the basis for U.S. standards.
This final rule allows EFVS to be used by foreign as well as U.S.
operators; therefore, there is a neutral effect on foreign operators.
In addition, the rule imposes no unnecessary obstacles to the foreign
commerce of the United States.
XIII. Unfunded Mandates Assessment
The Unfunded Mandates Reform Act of 1995 (the Act), enacted as Pub.
L. 104-4 on March 22, 1995 is intended, among other things, to curb the
practice of imposing unfunded Federal mandates on State, local, and
tribal governments. Title II of the Act requires each Federal agency to
prepare a written statement assessing the effects of any Federal
mandate in a proposed final agency rule that may result in an
expenditure of $100 million or more expenditure (adjusted annually for
inflation) in any one year by State, local, and tribal governments, in
the aggregate, or by the private sector; such a mandate is deemed to be
a ``significant regulatory action.''
The final rule does not contain such a mandate. Therefore, the
requirements of Title II of the Unfunded Mandates Reform Act of 1995 do
not apply.
XIV. Executive Order 13132, Federalism
The FAA has analyzed this proposed rule under the principles and
criteria of Executive Order 13132, Federalism. The FAA has determined
that this action would not have a substantial direct effect on the
States, on the relationship between the national government and the
States, or on the distribution of power and responsibilities among the
various levels of government. Therefore, we determined that this notice
does not have federalism implications.
XV. Environmental Analysis
FAA Order 1050.1D defines FAA action as that may be categorically
excluded from preparation of a National Environmental Policy Act (NEPA)
environmental impact statement. In accordance with FAA Order 1050.1D,
appendix 4, paragraph 4(j), this proposed rulemaking action qualifies
for a categorical exclusion.
XVI. Energy Impact
The energy impact of this proposed rule has been assessed in
accordance with the Energy Policy and Conservation Act (EPCA) (Pub. L.
94-163, as amended; 42 U.S.C. 6362) and FAA Order 1053.1. The FAA has
determined that the proposed rule is not a major regulatory action
under the provisions of the EPCA.
List of Subjects
14 CFR Part 1
Air transportation.
14 CFR Part 91
Agriculture, Air traffic control, Aircraft, Airmen, Airports,
Aviation safety, Freight.
14 CFR Part 121
Air carriers, Aircraft, Airmen, Aviation safety, Charter Flights,
Safety, Transportation.
14 CFR Parts 125 and 135
Aircraft, Airmen, Aviation safety.
The Amendments
0
In consideration of the foregoing, the Federal Administration Aviation
amends chapter I of 14 CFR as follows:
PART 1--DEFINITIONS AND ABBREVIATIONS
0
1. The authority for part 1 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
0
2. Amend Sec. 1.1 by adding the following definitions in alphabetical
order to read as follows:
Sec. 1.1 General definitions.
* * * * *
Enhanced flight visibility (EFV) means the average forward
horizontal distance, from the cockpit of an aircraft in flight, at
which prominent topographical objects may be clearly distinguished and
identified by day or night by a pilot using an enhanced flight vision
system.
Enhanced flight vision system (EFVS) means an electronic means to
provide a display of the forward external scene topography (the natural
or manmade features of a place or region especially in a way to show
their relative positions and elevation) through the use of imaging
sensors, such as a forward looking infrared, millimeter wave
radiometry, millimeter wave radar, low light level image intensifying.
* * * * *
Synthetic vision means a computer-generated image of the external
scene topography from the perspective of the flight deck that is
derived from aircraft attitude, high-precision navigation solution, and
database of terrain, obstacles and relevant cultural features.
Synthetic vision system means an electronic means to display a
synthetic vision image of the external scene topography to the flight
crew.
* * * * *
0
3. Amend Sec. 1.2 by adding the following abbreviation in alphabetical
order to read as follows:
[[Page 1640]]
Sec. 1.2 Abbreviations and symbols.
* * * * *
EFVS means enhanced flight vision system.
* * * * *
PART 91--GENERAL OPERATING AND FLIGHT RULES
0
4. The authority citation for part 91 continues to read as follows:
Authority: 49 U.S.C. 106(g), 1155, 40103, 40113, 40120, 44101,
44111, 44701, 44709, 44711, 44712, 44715, 44716, 44717, 44722,
46306, 46315, 46316, 46504, 46506-46507, 47122, 47508, 47528-47531,
articles 12 and 29 of the Convention on International Civil Aviation
(61 Stat. 1180).
0
5. Amend Sec. 91.175 by revising paragraphs (c) introductory text,
(d), and (e)(1) introductory text, and by adding paragraphs (l) and (m)
to read as follows:
Sec. 91.175 Takeoff and landing under IFR.
* * * * *
(c) Operation below DH or MDA. Except as provided in paragraph (l)
of this section, where a DH or MDA is applicable, no pilot may operate
an aircraft, except a military aircraft of the United States, at any
airport below the authorized MDA or continue an approach below the
authorized DH unless--
* * * * *
(d) Landing. No pilot operating an aircraft, except a military
aircraft of the United States, may land that aircraft when--
(1) For operations conducted under paragraph (l) of this section,
the requirements of (l)(4) of this section are not met; or
(2) For all other part 91 operations and parts 121, 125, 129, and
135 operations, the flight visibility is less than the visibility
prescribed in the standard instrument approach procedure being used.
(e) * * *
(1) Whenever operating an aircraft pursuant to paragraph (c) or (l)
of this section and the requirements of that paragraph are not met at
either of the following times:
* * * * *
(l) Approach to straight-in landing operations below DH, or MDA
using an enhanced flight vision system (EFVS). For straight-in
instrument approach procedures other than Category II or Category III,
no pilot operating under this section or Sec. Sec. 121.651, 125.381,
and 135.225 of this chapter may operate an aircraft at any airport
below the authorized MDA or continue an approach below the authorized
DH and land unless--
(1) The aircraft is continuously in a position from which a descent
to a landing on the intended runway can be made at a normal rate of
descent using normal maneuvers, and, for operations conducted under
part 121 or part 135 of this chapter, the descent rate will allow
touchdown to occur within the touchdown zone of the runway of intended
landing;
(2) The pilot determines that the enhanced flight visibility
observed by use of a certified enhanced flight vision system is not
less than the visibility prescribed in the standard instrument approach
procedure being used;
(3) The following visual references for the intended runway are
distinctly visible and identifiable to the pilot using the enhanced
flight vision system:
(i) The approach light system (if installed); or
(ii) The following visual references in both paragraphs
(l)(3)(ii)(A) and (B) of this section:
(A) The runway threshold, identified by at least one of the
following:
(1) The beginning of the runway landing surface;
(2) The threshold lights; or
(3) The runway end identifier lights.
(B) The touchdown zone, identified by at least one of the
following:
(1) The runway touchdown zone landing surface;
(2) The touchdown zone lights;
(3) The touchdown zone markings; or
(4) The runway lights.
(4) At 100 feet above the touchdown zone elevation of the runway of
intended landing and below that altitude, the flight visibility must be
sufficient for the following to be distinctly visible and identifiable
to the pilot without reliance on the enhanced flight vision system to
continue to a landing:
(i) The lights or markings of the threshold; or
(ii) The lights or markings of the touchdown zone;
(5) The pilot(s) is qualified to use an EFVS as follows--
(i) For parts 119 and 125 certificate holders, the applicable
training, testing and qualification provisions of parts 121, 125, and
135 of this chapter;
(ii) For foreign persons, in accordance with the requirements of
the civil aviation authority of the State of the operator; or
(iii) For persons conducting any other operation, in accordance
with the applicable currency and proficiency requirements of part 61 of
this chapter;
(6) For parts 119 and 125 certificate holders, and part 129
operations specifications holders, their operations specifications
authorize use of EFVS; and
(7) The aircraft is equipped with, and the pilot uses, an enhanced
flight vision system, the display of which is suitable for maneuvering
the aircraft and has either an FAA type design approval or, for a
foreign-registered aircraft, the EFVS complies with all of the EFVS
requirements of this chapter.
(m) For purposes of this section, ``enhanced flight vision system''
(EFVS) is an installed airborne system comprised of the following
features and characteristics:
(1) An electronic means to provide a display of the forward
external scene topography (the natural or manmade features of a place
or region especially in a way to show their relative positions and
elevation) through the use of imaging sensors, such as a forward-
looking infrared, millimeter wave radiometry, millimeter wave radar,
and low-light level image intensifying;
(2) The EFVS sensor imagery and aircraft flight symbology (i.e., at
least airspeed, vertical speed, aircraft attitude, heading, altitude,
command guidance as appropriate for the approach to be flown, path
deviation indications, and flight path vector, and flight path angle
reference cue) are presented on a head-up display, or an equivalent
display, so that they are clearly visible to the pilot flying in his or
her normal position and line of vision and looking forward along the
flight path, to include:
(i) The displayed EFVS imagery, attitude symbology, flight path
vector, and flight path angle reference cue, and other cues, which are
referenced to this imagery and external scene topography, must be
presented so that they are aligned with and scaled to the external
view; and
(ii) The flight path angle reference cue must be displayed with the
pitch scale, selectable by the pilot to the desired descent angle for
the approach, and suitable for monitoring the vertical flight path of
the aircraft on approaches without vertical guidance; and
(iii) The displayed imagery and aircraft flight symbology do not
adversely obscure the pilot's outside view or field of view through the
cockpit window;
(3) The EFVS includes the display element, sensors, computers and
power supplies, indications, and controls. It may receive inputs from
an airborne navigation system or flight guidance system; and
(4) The display characteristics and dynamics are suitable for
manual control of the aircraft.
[[Page 1641]]
PART 121--OPERATING REQUIREMENTS: DOMESTIC FLAG, AND SUPPLEMENTAL
OPERATIONS
0
6. The authority citation for part 121 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 40119, 41706, 44101, 44701-
44702, 44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-
44904, 44912, 46105.
0
7. Amend Sec. 121.651 by revising paragraphs (c) introductory text and
(d) introductory text to read as follows:
Sec. 121.651 Takeoff and landing weather minimums: IFR: All
certificate holders.
* * * * *
(c) If a pilot has begun the final approach segment of an
instrument approach procedure in accordance with paragraph (b) of this
section, and after that receives a later weather report indicating
below-minimum conditions, the pilot may continue the approach to DH or
MDA. Upon reaching DH or at MDA, and at any time before the missed
approach point, the pilot may continue the approach below DH or MDA if
either the requirements of Sec. 91.175(l) of this chapter, or the
following requirements are met:
* * * * *
(d) A pilot may begin the final approach segment of an instrument
approach procedure other than a Category II or Category III procedure
at an airport when the visibility is less than the visibility minimums
prescribed for that procedure if that airport is served by an operative
ILS and an operative PAR, and both are used by the pilot. However, no
pilot may continue an approach below the authorized DH unless the
requirements of Sec. 91.175(l) of this chapter, or the following
requirements are met:
* * * * *
PART 125--CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING
CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF
6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH
AIRCRAFT
0
8. The authority citation for part 125 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44705, 44710-
44711, 44713, 44716-44717, 44722.
0
9. Amend Sec. 125.381 by revising paragraph (c) to read as follows:
Sec. 125.381 Takeoff and landing weather minimums: IFR.
* * * * *
(c) If a pilot initiates an instrument approach procedure based on
a weather report that indicates that the specified visibility minimums
exist and subsequently receives another weather report that indicates
that conditions are below the minimum requirements, then the pilot may
continue with the approach only if, the requirements of Sec. 91.175(l)
of this chapter, or both of the following conditions are met--
(1) The later weather report is received when the airplane is in
one of the following approach phases:
(i) The airplane is on a ILS approach and has passed the final
approach fix;
(ii) The airplane is on an ASR or PAR final approach and has been
turned over to the final approach controller; or
(iii) The airplane is on a nonprecision final approach and the
airplane--
(A) Has passed the appropriate facility or final approach fix; or
(B) Where a final approach fix is not specified, has completed the
procedure turn and is established inbound toward the airport on the
final approach course within the distance prescribed in the procedure;
and
(2) The pilot in command finds, on reaching the authorized MDA, or
DH, that the actual weather conditions are at or above the minimums
prescribed for the procedure being used.
* * * * *
PART 135--OPERATING REQUIREMENTS: COMMUTER AND ON-DEMAND OPERATIONS
0
10. The authority citation for part 135 continues to read as follows:
Authority: 49 U.S.C. 106(g), 44113, 44701-44702, 44705, 44709,
44711-44713, 44715-44717, 44722.
0
11. Amend Sec. 135.225 by revising paragraph (c) to read as follows:
Sec. 135.225 IFR: Takeoff, approach, and landing minimums.
* * * * *
(c) If a pilot has begun the final approach segment of an
instrument approach to an airport under paragraph (b) of this section,
and the pilot receives a later weather report indicating that
conditions have worsened to below the minimum requirements, then the
pilot may continue the approach only if the requirements of Sec.
91.175(l) of this chapter, or both of the following conditions, are
met--
(1) The later weather report is received when the aircraft is in
one of the following approach phases:
(i) The aircraft is on an ILS final approach and has passed the
final approach fix;
(ii) The aircraft is on an ASR or PAR final approach and has been
turned over to the final approach controller; or
(iii) The aircraft is on a nonprecision final approach and the
aircraft--
(A) Has passed the appropriate facility or final approach fix; or
(B) Where a final approach fix is not specified, has completed the
procedure turn and is established inbound toward the airport on the
final approach course within the distance prescribed in the procedure;
and
(2) The pilot in command finds, on reaching the authorized MDA or
DH, that the actual weather conditions are at or above the minimums
prescribed for the procedure being used.
* * * * *
Issued in Washington, DC, on January 5, 2004.
Marion C. Blakey,
Administrator.
[FR Doc. 04-427 Filed 1-6-04; 1:55 pm]
BILLING CODE 4910-13-P