[Federal Register Volume 75, Number 127 (Friday, July 2, 2010)]
[Rules and Regulations]
[Pages 38391-38394]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-16166]
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Rules and Regulations
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Federal Register / Vol. 75, No. 127 / Friday, July 2, 2010 / Rules
and Regulations
[[Page 38391]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM429; Special Conditions No. 25-407-SC]
Special Conditions: Boeing 757-200 With Enhanced Flight Vision
System
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the Boeing Model 757-
200 series airplanes. These airplanes, as modified by the Federal
Express Corporation, will have an advanced, enhanced-flight-visibility
system (EFVS). The EFVS is a novel or unusual design feature which
consists of a head-up display (HUD) system modified to display forward-
looking infrared (FLIR) imagery. The applicable airworthiness
regulations do not contain adequate or appropriate safety standards for
this design feature. These special conditions contain the additional
safety standards that the Administrator considers necessary to
establish a level of safety equivalent to that established by the
existing airworthiness standards.
DATES: The effective date of these special conditions is June 11, 2010.
We must receive your comments by July 22, 2010.
ADDRESSES: You must mail two copies of your comments to: Federal
Aviation Administration, Transport Airplane Directorate, Attn: Rules
Docket (ANM-113), Docket No. NM429, 1601 Lind Avenue, SW., Renton,
Washington 98057-3356. You may deliver two copies to the Transport
Airplane Directorate at the above address. You must mark your comments:
Docket No. NM429. You can inspect comments in the Rules Docket
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Dale Dunford, FAA, Transport Standards
Staff, ANM-111, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue, SW., Renton, Washington 98055-4056;
telephone (425) 227-2239; fax (425) 227-1320; e-mail:
[email protected].
SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and
opportunity for, prior public comment on these special conditions are
impracticable because these procedures would significantly delay
issuance of the design approval and thus delivery of the affected
aircraft. In addition, the substance of these special conditions has
been subject to the public-comment process in several prior instances
with no substantive comments received. The FAA therefore finds that
good cause exists for making these special conditions effective upon
issuance.
Comments Invited
We invite interested people to take part in this rulemaking by
sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data. We ask
that you send us two copies of written comments.
We will file in the docket all comments we receive, as well as a
report summarizing each substantive public contact with FAA personnel
concerning these special conditions. You can inspect the docket before
and after the comment closing date. If you wish to review the docket in
person, go to the address in the ADDRESSES section of this preamble
between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal
holidays.
We will consider all comments we receive on or before the closing
date for comments. We will consider comments filed late if it is
possible to do so without incurring expense or delay. We may change
these special conditions based on the comments we receive.
If you want us to acknowledge receipt of your comments on this
proposal, include with your comments a self-addressed, stamped postcard
on which you have written the docket number. We will stamp the date on
the postcard and mail it back to you.
Background
On June 23, 2009, the Federal Express Corporation applied for a
supplemental type certificate for the installation and operation of a
HUD and an EFVS on Boeing Model 757-200. The original type certificate
for the 757-200 airplanes is A2NM, revision 27, dated July 16, 2009.
The Boeing Model 757-200 is a transport-category, cargo-carrying
airplane that operates with a crew of two and that carries no
passengers. The model 757-200 airplane has a wing span of 125 feet, a
length of 155 feet, a maximum takeoff gross weight of 255,000 pounds,
is powered by two Pratt and Whitney PW2037, PW2040, PW2043, or Rolls-
Royce RB211 turbofan engines, and has a maximum range of 3,900 nautical
miles.
The electronic infrared image displayed between the pilot and the
forward windshield represents a novel or unusual design feature in the
context of 14 CFR 25.773. Section 25.773 was not written in
anticipation of such technology. The electronic image has the potential
to enhance the pilot's awareness of the terrain, hazards, and airport
features. At the same time, the image may partially obscure the pilot's
direct outside compartment view. Therefore, the FAA needs adequate
safety standards to evaluate the EFVS to determine that the imagery
provides the intended visual enhancements without undue interference
with the pilot's outside compartment view. The FAA intent is that the
pilot will be able to use a combination of the information seen in the
image, and the natural view of the outside scene seen through the
image, as safely and effectively as a pilot compartment view without an
EVS image, that is compliant with Sec. 25.773.
Although the FAA has determined that the existing regulations are
not adequate for certification of EFVSs, it believes that EFVSs could
be certified through application of appropriate safety criteria.
Therefore, the FAA has determined that special conditions should be
issued for certification of EFVS to provide a level of safety
equivalent to that provided by the standard in Sec. 25.773.
Note: The term ``enhanced vision system'' (EVS) in this document
refers to a system
[[Page 38392]]
comprised of a head-up display, imaging sensor(s), and avionics
interfaces that display the sensor imagery on the HUD, and overlay
that imagery with alpha-numeric and symbolic flight information.
However, the term has also been commonly used in reference to
systems that displayed the sensor imagery, with or without other
flight information, on a head-down display. For clarity, the FAA
created the term ``enhanced flight visibility system'' (EFVS) to
refer to certain EVS systems that meet the requirements of the new
operational rules--in particular, the requirement for a HUD and
specified flight information--and which can be used to determine
``enhanced flight visibility.'' An EFVS can be considered a subset
of a system otherwise labeled EVS.
On January 9, 2004, the FAA published revisions to operational
rules in 14 CFR parts 1, 91, 121, 125, and 135 to allow aircraft to
operate below certain altitudes during a straight-in instrument
approach while using an EFVS to meet visibility requirements.
Prior to this rule change, the FAA issued Special Conditions No.
25-180-SC, which applied to an EVS installed on Gulfstream Model G-V
airplanes. Those special conditions addressed the requirements for the
pilot compartment view and limited the scope of the intended functions
permissible under the operational rules at the time. The intended
function of the EVS imagery was to aid the pilot during the approach,
and allow the pilot to detect and identify the visual references for
the intended runway down to 100 feet above the touchdown zone. However,
the EVS imagery alone was not to be used as a means to satisfy
visibility requirements below 100 feet.
The recent operational rule change expands the permissible
application of certain EVSs that are certified to meet the new EFVS
standards. The new rule will allow the use of an EFVS for operation
below the minimum descent altitude or decision height to meet new
visibility requirements of Sec. 91.175(l). The purpose of these
special conditions is not only to address the issue of the ``pilot
compartment view,'' as was done by Special Conditions No. 25-180-SC,
but also to define the scope of intended function consistent with Sec.
91.175(l) and (m).
Type Certification Basis
Under the provisions of 14 CFR 21.101, the Federal Express
Corporation must show that the Boeing Model 757-200 airplanes, as
modified, comply with the regulations in the U.S. type-certification
basis established for those airplanes. The U.S. type-certification
basis for the airplanes is established in accordance with Sec. 21.21
and 21.17, and the type certification application date. The U.S. type-
certification basis for these airplane models is listed in Type
Certificate Data Sheet No. A2NM, revision 27, dated July 16, 2009,
which covers all variants of the 757 airplanes.
In addition, the certification basis includes certain special
conditions and exemptions that are not relevant to these special
conditions. Also, if the regulations incorporated by reference do not
provide adequate standards with respect to the change, the applicant
must comply with certain regulations in effect on the date of
application for the change.
If the Administrator finds that the applicable airworthiness
regulations (i.e., part 25 as amended) do not contain adequate or
appropriate safety standards for the Boeing Model 757-200 airplanes,
modified by Federal Express, because of a novel or unusual design
feature, special conditions are prescribed under the provisions of
Sec. 21.16.
Special conditions, as defined in Sec. 11.19, are issued in
accordance with Sec. 11.38 and become part of the type-certification
basis in accordance with Sec. 21.101.
Special conditions are initially applicable to the model for which
they are issued. Should the applicant apply for a supplemental type
certificate to modify any other model included on the same type
certificate, to incorporate the same novel or unusual design feature,
the special conditions would also apply to the other model.
Novel or Unusual Design Features
The Boeing Model 757-200 airplanes will incorporate an EFVS, which
is a novel or unusual design feature. The EFVS is a novel or unusual
design feature because it projects a video image derived from a FLIR
camera through the HUD. The EFVS image is projected in the center of
the ``pilot compartment view,'' which is governed by Sec. 25.773. The
image is displayed with HUD symbology and overlays the forward outside
view. Therefore, Sec. 25.773 does not contain appropriate safety
standards for the EFVS display.
Operationally, during an instrument approach, the EFVS image is
intended to enhance the pilot's ability to detect and identify ``visual
references for the intended runway'' [see Sec. 91.175(l)(3)] to
continue the approach below decision height or minimum descent
altitude. Depending on atmospheric conditions and the strength of
infrared energy emitted and/or reflected from the scene, the pilot can
see these visual references in the image better than he or she can see
them through the window without EFVS.
Scene contrast detected by infrared sensors can be much different
from that detected by natural pilot vision. On a dark night, thermal
differences of objects which are not detectable by the naked eye are
easily detected by many imaging infrared systems. On the other hand,
contrasting colors in visual wavelengths may be distinguished by the
naked eye but not by an imaging infrared system. Where thermal contrast
in the scene is sufficiently detectable, the pilot can recognize shapes
and patterns of certain visual references in the infrared image.
However, depending on conditions, those shapes and patterns in the
infrared image can appear significantly different than they would with
normal vision. Considering these factors, the EFVS image needs to be
evaluated to determine that it can be accurately interpreted by the
pilot.
The EFVS image may improve the pilot's ability to detect and
identify items of interest. However, the EFVS needs to be evaluated to
determine that the imagery allows the pilot to perform the normal
flight-crew duties and adequately see outside the window through the
image, consistent with the safety intent of Sec. 25.773(a)(2).
Compared to a HUD displaying the EFVS image and symbology, a HUD
that only displays stroke-written symbols is easier to see through.
Stroke symbology illuminates a small fraction of the total display area
of the HUD, leaving much of that area free of reflected light that
could interfere with the pilot's view out the window through the
display. However, unlike stroke symbology, the video image illuminates
most of the total display area of the HUD (approximately 30 degrees
horizontally and 25 degrees vertically) which is a significant fraction
of the pilot compartment view. The pilot cannot see around the larger
illuminated portions of the video image, but must see the outside scene
through it.
Unlike the pilot's external view, the EFVS image is a monochrome,
two-dimensional display. Many, but not all, of the depth cues found in
the natural view are also found in the image. The quality of the EFVS
image and the level of EFVS infrared-sensor performance could depend
significantly on conditions of the atmospheric and external light
sources. The pilot needs adequate control of sensor gain and image
brightness, which can significantly affect image quality and
transparency (i.e., the ability to see the outside view through the
image). Certain system characteristics could create distracting and
confusing display artifacts. Finally, because this is a sensor-based
system intended to
[[Page 38393]]
provide a conformal perspective corresponding with the outside scene,
the system must be able to ensure accurate alignment. Therefore, safety
standards are needed for each of the following factors:
An acceptable degree of image transparency;
Image alignment;
Lack of significant distortion; and
The potential for pilot confusion or misleading
information.
Section 25.773, Pilot compartment view, specifies that ``Each pilot
compartment must be free of glare and reflection that could interfere
with the normal duties of the minimum flight crew * * *'' In issuing
Sec. 25.773, the FAA did not anticipate the development of the EFVS
and does not consider that Sec. 25.773 adequately addresses the
specific issues related to such a system. Therefore, the FAA has
determined that special conditions are needed to address the specific
issues particular to the installation and use of an EFVS.
Discussion
The EFVS is intended to present an enhanced view during the landing
approach. This enhanced view would help the pilot see and recognize
external visual references, as required by Sec. 91.175(l), and to
visually monitor the integrity of the approach, as described in FAA
Order 6750.24D (``Instrument Landing System and Ancillary Electronic
Component Configuration and Performance Requirements,'' dated March 1,
2000).
Based on this approved functionality, users would seek to obtain
operational approval to conduct approaches--including approaches to
Type I runways--in visibility conditions much lower than those for
conventional Category I.
The purpose of these special conditions is to ensure that the EFVS
to be installed can perform the following functions:
Present an enhanced view that aids the pilot during the
approach.
Provide enhanced flight visibility to the pilot that is no
less than the visibility prescribed in the standard instrument-approach
procedure.
Display an image that the pilot can use to detect and
identify the ``visual references for the intended runway'' required by
14 CFR 91.175(l)(3), to continue the approach with vertical guidance to
100 feet height above the touchdown-zone elevation.
Depending on the atmospheric conditions and the particular visual
references that happen to be distinctly visible and detectable in the
EFVS image, these functions would support its use by the pilot to
visually monitor the integrity of the approach path.
Compliance with these special conditions does not affect the
applicability of any of the requirements of the operating regulations
(i.e., 14 CFR parts 91, 121, and 135). Furthermore, use of the EFVS
does not change the approach minima prescribed in the standard
instrument approach procedure being used; published minima still apply.
The FAA certification of this EFVS is limited as follows:
1. The infrared-based EFVS image will not be certified as a means
to satisfy the requirements for descent below 100 feet height above
touchdown.
2. The EFVS may be used as a supplemental device to enhance the
pilot's situational awareness during any phase of flight or operation
in which its safe use has been established.
3. An EFVS image may provide an enhanced image of the scene that
may compensate for any reduction in the clear outside view of the
visual field framed by the HUD combiner. The pilot must be able to use
this combination of information seen in the image and the natural view
of the outside scene, seen through the image, as safely and effectively
as the pilot would use a pilot compartment view without an EFVS image
that is compliant with Sec. 25.773. This is the fundamental objective
of the special conditions.
The FAA will also apply additional certification criteria, not as
special conditions, for compliance with related regulatory
requirements, such as Sec. Sec. 25.1301 and 25.1309. These additional
criteria address certain image characteristics, installation,
demonstration, and system safety.
Image-characteristics criteria include the following:
Resolution,
Luminance,
Luminance uniformity,
Low-level luminance,
Contrast variation,
Display quality,
Display dynamics (e.g., jitter, flicker, update rate, and
lag), and
Brightness controls.
Installation criteria address visibility and access to EFVS
controls, and integration of EFVS in the cockpit.
The EFVS demonstration criteria address the flight and
environmental conditions that need to be covered.
The FAA also intends to apply certification criteria relevant to
high-intensity radiated fields (HIRF) and lightning protection.
Applicability
As discussed above, these special conditions are applicable to
Boeing Model 757-200 airplanes. Should the Federal Express Corporation
apply at a later date for a supplemental type certificate to modify any
other model included on Type Certificate No. A2NM to incorporate the
same novel or unusual design feature, the special conditions would
apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on Boeing 757-200 airplanes. It is not a rule of general applicability
and it affects only the applicant who applied to the FAA for approval
of these features on the airplane.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
0
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
0
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type-certification basis for Boeing Model 757-200 airplanes
modified by the Federal Express Corporation.
1. The EFVS imagery on the HUD must not degrade the safety of
flight, or interfere with the effective use of outside visual
references for required pilot tasks, during any phase of flight in
which it is to be used.
2. To avoid unacceptable interference with the safe and effective
use of the pilot compartment view, the EFVS device must meet the
following requirements:
a. The EFVS design must minimize unacceptable display
characteristics or artifacts (e.g. noise, ``burlap'' overlay, running
water droplets) that obscure the desired image of the scene, impair the
pilot's ability to detect and identify visual references, mask flight
hazards, distract the pilot, or otherwise degrade task performance or
safety.
b. Automatic control of EFVS display brightness must be
sufficiently effective, in dynamically changing background (ambient)
lighting conditions, to prevent full or partial blooming of the display
that would distract the pilot, impair the pilot's ability to detect and
identify visual references, mask flight hazards, or otherwise degrade
task performance or safety.
c. A readily accessible control must be provided that permits the
pilot to immediately deactivate and reactivate display of the EFVS
image on demand
[[Page 38394]]
without removing the pilot's hands from the primary flight controls
(yoke or equivalent) or thrust control.
d. The EFVS image on the HUD must not impair the pilot's use of
guidance information, or degrade the presentation and pilot awareness
of essential flight information, displayed on the HUD, such as alerts,
airspeed, attitude, altitude and direction, approach guidance,
windshear guidance, Traffic Alert and Collision Avoidance System (TCAS)
resolution advisories, or unusual-attitude recovery cues.
e. The EFVS image and the HUD symbols--which are spatially
referenced to the pitch scale, outside view and image--must be scaled
and aligned (i.e., conformal) to the external scene. In addition, the
EFVS image and the HUD symbols--when considered singly or in
combination--must not be misleading, cause pilot confusion, or increase
workload. Airplane attitudes or cross-wind conditions may cause certain
symbols (e.g., the zero-pitch line or flight path vector) to reach
field-of-view limits such that they cannot be positioned conformally
with the image and external scene. In such cases, these symbols may be
displayed but with an altered appearance which makes the pilot aware
that they are no longer displayed conformally (for example,
``ghosting'').
f. A HUD system used to display EFVS images must, if previously
certified, continue to meet all of the requirements of the original
approval. If the HUD has not been previously approved, it must be found
to meet the basic HUD certification criteria documented in the HUD
issue paper.
3. The safety and performance of the pilot tasks associated with
the use of the pilot compartment view must not be degraded by the
display of the EFVS image. Pilot tasks which must not be degraded by
the EFVS image include:
a. Detection, accurate identification, and maneuvering, as
necessary, to avoid traffic, terrain, obstacles, and other hazards of
flight.
b. Accurate identification and utilization of visual references
required for every task relevant to the phase of flight.
4. The EFVS must be shown to be compliant with these requirements,
under the provisions of Sec. Sec. 91.175(l) and 121.651, with the
following intended functions:
a. Presenting an image that would aid the pilot during a straight-
in instrument approach.
b. Enable the pilot to determine that the ``enhanced flight
visibility,'' as required by Sec. 91.175(l)(2) and referenced in Sec.
121.651, is adequate for descent and operation below minimum descent
altitude/decision height.
c. Enabling the pilot to use the EFVS imagery to detect and
identify the ``visual references for the intended runway,'' required by
Sec. 91.175(l)(3), to continue the approach with vertical guidance to
100 feet height above touchdown-zone elevation.
5. Use of EFVS for instrument-approach operations must be in
accordance with the provisions of Sec. 91.175(l) and (m), and Sec.
121.651 where applicable. Appropriate limitations must be stated in the
Operating Limitations section of the airplane flight manual to prohibit
the use of the EFVS for functions that have not been found to be
acceptable.
Issued in Renton, Washington, on June 11, 2010.
Jeffrey Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2010-16166 Filed 7-1-10; 8:45 am]
BILLING CODE 4910-13-P