[Federal Register Volume 69, Number 156 (Friday, August 13, 2004)]
[Proposed Rules]
[Pages 50240-50254]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-18351]
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Part II
Department of Transportation
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Federal Aviation Administration
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14 CFR Part 25
Safety Standards for Flight Guidance Systems and Proposed Revisions to
Advisory Circular 25-1329-1A, Automatic Pilot Systems Approval;
Proposed Rule and Notice
Federal Register / Vol. 69, No. 156 / Friday, August 13, 2004 /
Proposed Rules
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2004-18775; Notice No. 04-11]
RIN 2120-AI41
Safety Standards for Flight Guidance Systems
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The Federal Aviation Administration proposes to amend the
airworthiness standards for transport category airplanes concerning
flight guidance systems. The proposed standards address the
performance, safety, failure protection, alerting, and basic
annunciation of these systems. This proposed rule is necessary to
address flight guidance system vulnerabilities and to consolidate and
standardize regulations for functions within those systems. This
proposed rule would also update the current regulations regarding the
latest technology and functionality. Adopting this proposal would
eliminate significant regulatory differences between the airworthiness
standards of the U.S. and the Joint Aviation Authorities of Europe.
DATES: Send your comments on or before October 12, 2004.
ADDRESSES: You may send comments [Docket Number FAA-2004-18775] using
any of the following methods:
DOT Docket Web site: Go to http://dms.dot.gov and follow
the instructions for sending your comments electronically.
Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your
comments electronically.
Mail: Docket Management Facility; U.S. Department of
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401,
Washington, DC 20590-001.
Fax: 1-202-493-2251.
Hand Delivery: Room PL-401 on the plaza level of the
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For more information on the rulemaking process, see the
SUPPLEMENTARY INFORMATION section of this document.
Privacy: We will post all comments we receive, without change, to
http://dms.dot.gov, including any personal information you provide. For
more information, see the Privacy Act discussion in the SUPPLEMENTARY
INFORMATION section of this document.
Docket: To read background documents or comments received, go to
http://dms.dot.gov at any time or to Room PL-401 on the plaza level of
the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Gregg Bartley, FAA, Airplane and
Flight Crew Interface Branch (ANM-111), Transport Airplane Directorate,
Aircraft Certification Service, 1601 Lind Avenue SW., Renton,
Washington 98055-4056; telephone (425) 227-2889; facsimile 425-227-
1320; e-mail [email protected].
SUPPLEMENTARY INFORMATION:
How Do I Submit Comments to This NPRM?
The FAA invites interested persons to participate in this
rulemaking by submitting written comments, data, or views. We also
invite comments relating to the economic, environmental, energy, or
federalism impacts that might result from adopting the proposals in
this document. The most helpful comments reference a specific portion
of the proposal, 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 this proposed rulemaking. The docket is available for public
inspection 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 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. You may also review the docket using the
Internet at the web address in the ADDRESSES section.
Privacy Act: Using the search function of our docket Web site,
anyone can find and read the comments received into any of our dockets,
including the name of the individual sending the comment (or signing
the comment 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 (65 FR 19477-78) or you may visit
http://dms.dot.gov.
Before acting on this proposal, 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 this proposal in light of the comments
we receive.
If you want the FAA to acknowledge receipt of your comments on this
proposal, include with your comments a pre-addressed, stamped postcard
on which the docket number appears. We will stamp the date on the
postcard and mail it to you.
How Can I Obtain a Copy of This NPRM?
You can get an electronic copy using the Internet by:
(1) Searching the Department of Transportation's electronic Docket
Management System (DMS) Web page (http://dms.dot.gov/search);
(2) Visiting the Office of Rulemaking's Web page at http://www.faa.gov/avr/arm/index.cfm; 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. Make
sure to identify the docket number, notice number, or amendment number
of this rulemaking.
Background
What Prompted This Proposed Rule?
In response to several incidents and accidents that highlight
difficulties for flightcrews interacting with the increasing automation
of flight decks, the FAA formed a Human Factors Team (HFT). The team
included representatives of the National Aeronautics and Space
Administration (NASA) and the Joint Aviation Authority of Europe (JAA),
as well as technical advisers from Ohio State University, the
University of Illinois, and the University of Texas. The HFT evaluated
flightcrew/flight deck automation interfaces for the current generation
of transport category airplanes. They issued a report on June 18, 1996,
titled ``The Interfaces Between Flightcrews and Modern Flight Deck
Systems.'' A copy of the HFT report is included in the official docket.
The main impetus for the HFT study was an accident in Nagoya,
Japan, on April 26, 1994, involving an Airbus 300-600 operated by China
Airlines. Contributing to that accident were conflicting actions taken
by the
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flightcrew and the airplane's autopilot. The flightcrew tried to
correct the autopilot's directions. The combination of out-of-trim
conditions, high engine thrust, and flaps that were retracted too far
led to a stall, which resulted in an accident involving 264 fatalities.
Although this particular accident involved an A300-600, other
accidents, incidents, and safety indicators demonstrate that this
problem is not confined to any one airplane type, manufacturer,
operator, or geographic region. On November 12, 1995, an MD-80 operated
by American Airlines descended below the minimum descent altitude,
clipped some trees, and landed short of the runway, in what was very
nearly a fatal accident. On July 13, 1996, a McDonnell Douglas MD-11
operated by American Airlines experienced an in-flight upset near
Westerly, Rhode Island. When the airplane was cleared to descend to
24,000 feet, the first officer initiated a descent by means of the
autopilot. With approximately 1,000 feet left in the descent, the
captain became concerned that the airplane might not level off at the
assigned altitude and instructed the first officer to slow the rate of
descent. The first officer adjusted the pitch thumbwheel on the
autopilot control panel. This maneuver proved ineffective. The captain
then took manual control of the airplane, began applying back pressure
to the control column, and disconnected the autopilot. Flight data
recorder data show the airplane experienced an immediate 2.3 G pitch
upset followed by more oscillations, resulting in four injuries.
The HFT identified issues that show vulnerabilities in flightcrew
management of automation and situation awareness. Specifically, there
were concerns about:
Pilot understanding of automation's capabilities,
limitations, modes, and operating principles and techniques. The HFT
frequently heard about automation ``surprises,'' where the automation
behaved in ways the flightcrew did not expect. The flightcrews, from
operational experience, commonly asked: ``Why did it do that?'' ``What
is it doing now?'' and ``What will it do next?'
Differing pilot decisions about the appropriate automation
level to use or whether to turn the automation on or off when they get
into unusual or non-normal situations. This may also lead to potential
mismatches with the manufacturer's assumptions about how the flightcrew
will use the automation.
Flightcrew situation awareness issues included vulnerabilities in,
for example:
Automation/mode awareness. This was an area where the
researchers heard a universal message of concern about each of the
aircraft in the study.
Flight path awareness, including insufficient terrain
awareness (sometimes involving loss of control or controlled flight
into terrain) and energy awareness (especially low energy state).
The team concluded that these vulnerabilities exist because of some
interrelated deficiencies in the current aviation system:
Insufficient communication and coordination. Examples
include lack of communication about in-service experience within and
between organizations; incompatibilities between the air traffic system
and airplane capabilities; poor interfaces between organizations, and
lack of coordination of research needs and results between the research
community, designers, regulators, and operators.
Processes used for design, training, and regulatory
functions that inadequately address human performance issues. As a
result, users can be surprised by subtle behavior or overwhelmed by the
complexity embedded in systems within the current operating
environment. Process improvements are needed to provide the framework
for consistent application of principles and methods for removing
vulnerabilities in design, training, and operations.
Insufficient criteria, methods, and tools for design,
training, and evaluation. Existing methods, data, and tools are
inadequate to evaluate and resolve many of the important human
performance issues. It is fairly easy to get agreement that automation
should be human-centered, or that potentially hazardous situations
should be avoided; it is much more difficult to get agreement on how to
achieve these objectives.
Insufficient knowledge and skills. Designers, pilots,
operators, regulators, and researchers do not always have adequate
knowledge and skills in certain areas related to human performance. The
team was concerned that investments in necessary levels of human
expertise were being reduced in response to economic pressures. For
example, two-thirds to three-quarters of all accidents had flightcrew
error cited (during the study) as a major factor.
Insufficient understanding and consideration of cultural
differences in design, training, operations, and evaluation. The
aviation community has an inadequate understanding of the influence of
culture and language on flightcrew/automation interaction. Cultural
differences may reflect differences in the country of origin,
philosophy of regulators, organizational philosophy, or other factors.
There is a need to improve the aviation community's understanding and
consideration of the implications of cultural influences on human
performance.
Not all wide-reaching problems uncovered by the human factors team
listed above can be corrected in one rulemaking project. The safety
issues addressed in this proposal are the following:
Insufficient crew awareness of flight guidance system
(FGS) behavior and operation.
Hazardous autopilot transients resulting from
disengagement, including a manual pilot override of an engaged
autopilot.
FGS mode confusion resulting in crew errors (for instance,
altitude violation).
History of lack of awareness of unusual/hazardous
attitudes during FGS operations (accidents and incidents).
History of lack of speed awareness (accidents and
incidents).
Operation in icing conditions.
Function of the Flight Guidance System
The FGS is intended to assist the flightcrew in the basic control
and guidance of the airplane. The FGS provides workload relief to the
flightcrew and a means to more accurately fly an intended flight path.
The following functions make up the flight guidance system:
1. Autopilot--automated airplane maneuvering and handling
capabilities.
2. Autothrust--automated propulsion control.
3. Flight Director--the display of steering commands that provide
vertical and horizontal path guidance, whether displayed ``heads down''
or ``heads up.'' A heads up display is a flight instrumentation that
allows the pilot of an airplane to watch the instruments while looking
ahead of the airplane for the approach lights or the runway.
Flight guidance systems functions also include the flight deck
alerting, status, mode annunciations (instrument displays), and any
situational information required by those functions displayed to the
flightcrew. Also included are those functions necessary to provide
guidance and control with an approach and landing system, such as:
Instrument landing system (ILS).
Microwave landing system (MLS) (an instrument landing
system operating in the microwave spectrum that provides lateral and
vertical guidance to airplanes having compatible avionics equipment).
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Global navigation satellite system landing system (GLS).
The FGS definition does not include flight planning, flight path
construction, or any other function normally associated with a Flight
Management System (FMS).
Statement of the Problem
Several NTSB safety recommendations, as well as the FAA study
discussed above, have highlighted flight guidance system
vulnerabilities. The current regulations (Sec. 25.1329) regarding
flight guidance systems address only the autopilot system, except for
one specific regulation regarding the flight director switch position
(Sec. 25.1335). Not addressed is the autothrust system, and how it
relates to flight guidance. Therefore, there is a need to consolidate
and standardize regulations for all flight guidance system
functionality (autopilot, autothrust, and flight director).
Also needed is an updating of existing regulations to match
technology advances. Current regulations do not fully address the
latest technology or new functionality available. In addition, proposed
and recent rulemaking activity, such as the interaction of systems and
structure, flight test, and human factors, will make certain aspects of
the existing flight guidance systems regulations redundant, in conflict
with other regulations, or confusing and difficult to understand.
Finally, there is a need to harmonize regulations between the FAA
and the Joint Aviation Authorities (JAA) that would not only benefit
the aviation industry economically, but also maintain the necessary
high level of aviation safety.
NTSB Recommendations
Safety recommendations issued by the NTSB in recent years that
highlight vulnerabilities in the flight guidance systems of today's
transport airplanes are listed below:
NTSB Safety Recommendation A-92-035: ``Revise Advisory
Circular 25.1329-1A to add guidance regarding autopilot failures that
can result in changes in attitude at rates that may be imperceptible to
the flightcrew and thus remain undetected until the airplane reaches
significant attitude deviations.''
NTSB Safety Recommendation A-98-098: ``Require all
manufacturers of transport-category airplanes to incorporate logic into
all new and existing transport-category airplanes that have autopilots
installed to provide a cockpit aural warning to alert pilots when the
airplane's bank and/or pitch exceeds the autopilot's maximum bank and/
or pitch command limits.''
NTSB Safety Recommendation A-99-043: ``Require all new
transport category airplane autopilot systems to be designed to prevent
upsets when manual inputs to the flight controls are made.''
What Are the Relevant Airworthiness Standards in the United States?
In the United States, the airworthiness standards for type
certification of transport category airplanes are contained in Title
14, Code of Federal Regulations (CFR) part 25. Manufacturers of
transport category airplanes must show that each airplane they produce
of a different type design complies with the appropriate part 25
standards. These standards apply to:
Airplanes manufactured within the U.S., and
Airplanes manufactured in other countries and imported to
the U.S. under a bilateral airworthiness agreement.
What Are the Relevant Airworthiness Standards in Europe?
In Europe, the airworthiness standards for type certification of
transport category airplanes are contained in Joint Aviation
Requirements (JAR)-25, which are based on part 25. These were developed
by the Joint Aviation Authorities (JAA) of Europe to provide a common
set of airworthiness standards within the European aviation community.
Thirty-seven European countries accept airplanes type certificated to
the JAR-25 standards, including airplanes manufactured in the U.S. that
are type certificated to JAR-25 standards for export to Europe.
What Is ``Harmonization'' and How Did It Start?
Although part 25 and JAR-25 are very similar, they are not
identical in every respect. When airplanes are type certificated to
both sets of standards, the differences between part 25 and JAR-25 can
result in substantial added costs to manufacturers and operators. These
added costs, however, often do not bring about an increase in safety.
Often, part 25 and JAR-25 may contain different requirements to
accomplish the same safety intent. Consequently, manufacturers are
usually burdened with meeting the requirements of both sets of
standards without a corresponding increase in the level of safety.
Recognizing that a common set of standards would not only benefit
the aviation industry economically, but also maintain the necessary
high level of safety, the FAA and the JAA began an effort in 1988 to
``harmonize'' their respective aviation standards. The goal of the
harmonization effort is to ensure that:
Where possible, standards do not require domestic and
foreign parties to manufacture or operate to different standards for
each country involved; and
The standards adopted are mutually acceptable to the FAA
and the foreign aviation authorities.
The FAA and JAA have identified many significant regulatory
differences (SRD) between the wording of part 25 and JAR-25. Both the
FAA and the JAA consider ``harmonization'' of the two sets of standards
a high priority.
What Is the European Aviation Safety Authority?
The new European Aviation Safety Authority (EASA) was established
and formally came into being on September 28, 2003. The JAA worked with
the European Commission (EC) to develop a plan to ensure a smooth
transition from JAA to EASA. As part of the transition, the EASA will
absorb all functions and activities of the JAA, including its efforts
to harmonize JAA regulations with those of the U.S. This rule is a
result of the FAA and JAA harmonization rulemaking activities. These
JAR standards have already been incorporated into the EASA
``Certification Specifications for Large Aeroplanes'' CS-25, in similar
if not identical language. The EASA CS-25 became effective October 17,
2003.
What Is ARAC and What Role Does It Play in Harmonization?
After initiating the first steps towards harmonization, the FAA and
JAA soon realized that traditional methods of rulemaking and
accommodating different administrative procedures was neither
sufficient nor adequate to make appreciable progress towards fulfilling
the harmonization goal. The FAA identified the Aviation Rulemaking
Advisory Committee (ARAC) as an ideal resource for assisting in
resolving harmonization issues, and, in 1992, the FAA tasked ARAC to
undertake the entire harmonization effort.
The FAA had formally established ARAC in 1991 (56 FR 2190, January
22, 1991), to provide advice and recommendations concerning the full
range of the FAA's safety-related rulemaking activity. The FAA sought
this advice to develop better rules in less overall time and using
fewer FAA resources than previously needed. The committee provides the
FAA firsthand
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information and insight from interested parties regarding potential new
rules or revisions of existing rules.
There are 74 member organizations on the committee representing a
wide range of interests within the aviation community. Meetings of the
committee are open to the public, except as authorized by section 10(d)
of the Federal Advisory Committee Act.
The ARAC establishes working groups to develop recommendations for
resolving specific airworthiness issues. Tasks assigned to working
groups are published in the Federal Register. Although working group
meetings are not generally open to the public, the FAA solicits
participation in working groups from interested members of the public
who possess knowledge or experience in the task areas. Working groups
report directly to the ARAC, and the ARAC must accept a working group
proposal before ARAC presents the proposal to the FAA as an advisory
committee recommendation.
The activities of the ARAC will not, however, circumvent the public
rulemaking procedures; nor is the FAA limited to the rule language
``recommended'' by ARAC. If the FAA accepts an ARAC recommendation, the
agency proceeds with the normal public rulemaking procedures. Any ARAC
participation in a rulemaking package is fully disclosed in the public
docket.
This rulemaking has been identified as a ``fast track'' project.
Further details on the Fast Track Program can be found in the tasking
statement (64 FR 66522, November 26, 1999) and the first NPRM published
under this program, Fire Protection Requirements for Powerplant
Installations on Transport Category Airplanes (65 FR 36978, June 12,
2000).
What Are the Current 14 CFR and JAR Standards, Certification
Specifications for Large Airplanes?
The current text of 14 CFR 25.1329 (amendment 25-46) is:
Sec. 25.1329 Automatic pilot system.
(a) Each automatic pilot system must be approved and must be
designed so that the automatic pilot can be quickly and positively
disengaged by the pilots to prevent it from interfering with their
control of the airplane.
(b) Unless there is automatic synchronization, each system must
have a means to readily indicate to the pilot the alignment of the
actuating device in relation to the control system it operates.
(c) Each manually operated control for the system must be
readily accessible to the pilots.
(d) Quick release (emergency) controls must be on both control
wheels, on the side of each wheel opposite the throttles.
(e) Attitude controls must operate in the plane and sense of
motion specified in Sec. Sec. 25.777(b) and 25.779(a) for cockpit
controls. The direction of motion must be plainly indicated on, or
adjacent to, each control.
(f) The system must be designed and adjusted so that, within the
range of adjustment available to the human pilot, it cannot produce
hazardous loads on the airplane, or create hazardous deviations in
the flight path, under any condition of flight appropriate to its
use either during normal operation, or in the event of a
malfunction, assuming that corrective action begins within a
reasonable period of time.
(g) If the automatic pilot integrates signals from auxiliary
controls or furnishes signals for operation of other equipment,
there must be positive interlocks and sequencing of engagement to
prevent improper operation. Protection against adverse interaction
of integrated components, resulting from a malfunction, is also
required.
(h) If the automatic pilot system can be coupled to airborne
navigation equipment, means must be provided to indicate to the
flight crew the current mode of operation. Selector switch position
is not acceptable as a means of indication.
The current text of 14 CFR 25.1335 (amendment 25-41) is:
Sec. 25.1335 Flight director systems.
If a flight director system is installed, means must be provided
to indicate to the flight crew its current mode of operation.
Selector switch position is not acceptable as a means of indication.
The current text of JAR 25.1329 (Change 15) is:
JAR 25.1329 Automatic Pilot System.
(a) Each automatic pilot system must be approved and must be
designed so that the automatic pilot can be quickly and positively
disengaged by the pilots to prevent it from interfering with their
control of the aeroplane.
(b) Unless there is automatic synchronization, each system must
have a means to readily indicate to the pilot the alignment of the
actuating device in relation to the control system it operates.
(c) Each manually operated control for the system must be
readily accessible to the pilots.
(d) Quick release (emergency) controls must be on both control
wheels, on the side of each wheel opposite the throttles.
(e) Attitude controls must operate in the plane and sense of
motion specified in JAR 25.777(b) and JAR 25.779(a) for cockpit
controls. The direction of motion must be plainly indicated on, or
adjacent to, each control.
(f) The system must be designed and adjusted so that, within the
range of adjustment available to the human pilot, it cannot produce
hazardous loads on the aeroplane, or create hazardous deviations in
the flight path, under any condition of flight appropriate to its
use, either during normal operation, or in the event of a
malfunction, assuming that corrective action begins within a
reasonable period of time.
(g) If the automatic pilot integrates signals from auxiliary
controls or furnishes signals for operation of other equipment,
there must be positive interlocks and sequencing of engagement to
prevent improper operation. Protection against adverse interaction
of integrated components, resulting from a malfunction, is also
required.
(h) Means must be provided to indicate to the flight crew the
current mode of operation and any modes armed by the pilot. Selector
switch position is not acceptable as a means of indication.
(i) A warning must be provided to each pilot in the event of
automatic or manual disengagement of the automatic pilot. (See JAR
25.1322 and its AMJ.)
The current text of JAR 25.1335 (Change 15) is:
JAR 25.1335 Flight Director Systems.
Means must be provided to indicate to the flight crew the
current mode of operation and any modes armed by the pilot. Selector
switch position is not acceptable as a means of indication.
What Are the Differences in the Standards and What Do Those Differences
Result In?
The only appreciable difference between the U.S. and European rules
is that the JAR requires a warning to each pilot in the event of
automatic or manual disengagement of the automatic pilot. This
requirement does not appear in 14 CFR 25.1329. American manufacturers
have been providing such a warning, however, as part of compliance with
14 CFR 25.1309, which requires that warning information be provided to
alert the crew to unsafe operating conditions. There is a minor
difference in the sounding period of the warning provided in American-
and European-manufactured airplanes that has resulted from differences
in advisory materials and accepted practice, and that difference does
affect certification. The harmonization of this rule (and accompanying
advisory material) would remove that difference.
What, if Any, Are the Differences in the Means of Compliance?
Compliance with the Sec. 25.1329 rule has largely followed the
advisory material found in FAA AC 25.1329-1A, dated July 8, 1968, or in
JAA Advisory Circular Joint (ACJ) 25.1329. Advances in autopilot
technology have outpaced both the FAA guidance and the more current JAA
ACJ 25.1329 material. Autopilot-related issue papers and interim policy
have been used to fill these gaps in the regulatory and acceptable
means of compliance material.
The regulations are applied in certification and validation of
products. To market American-manufactured airplanes in Europe, the
applicant must meet the requirements of part 25 and
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JAR-25. As a result, the certification is typically done to the more
stringent JAR-25 requirement.
Related Activity
Under the ARAC rulemaking process, the FAA provides ARAC with an
opportunity to review, discuss, and comment on the FAA's draft NPRM.
For this rulemaking, ARAC recommended several changes to the NPRM. (A
more detailed discussion of this process appears later in this
document.) The FAA agrees with some of those recommendations and has
revised the NPRM accordingly. However, we disagree with others, and
those recommendations, and our reasons for disagreeing are described
below in the Discussion of the Proposal section.
Discussion of the Proposal
What Is the General Scope of the Proposal?
The proposed change would revise, reorganize, and add additional
material to Sec. 25.1329. This change would address the autopilot,
autothrust, and flight director in a single section. It would change
the name of Sec. 25.1329 from ``Automatic pilot system'' to ``Flight
guidance system'' to reflect the inclusion of autothrust and flight
director. This proposed rule would cover the portion of the Heads Up
Display (HUD) that contains flight-guidance information displayed to
the pilot while manually flying the airplane. Other aspects of HUDs are
covered by various regulations that govern flight deck displays and
navigation information. This ensures consistency between the Heads Up
and Heads Down flight-guidance information displayed in the flight
deck.
The proposed change would incorporate new requirements specifically
to target potential pilot confusion about automatic mode reversions,
hazardous disengagement transients, speed protection, and potential
hazards during an autopilot override. The proposed change would remove
Sec. 25.1335, ``Flight director systems,'' and would amend Sec.
25.1329 to add a new paragraph (i).
How Does the Changed Product Rule (CPR) (Sec. 21.101--Designation of
Applicable Regulations) Relate to This Change?
The CPR must be considered when updating or adding a flight
guidance system. If a proposed change to a flight guidance system is
part of a significant product change, then Sec. 21.101(a) is
applicable unless one of the other exceptions of Sec. 21.101(b)
applies. Section 21.101(a) states that ``An applicant for a change must
show that the changed product complies with the airworthiness
requirements applicable to the category of the product in effect on the
date of the application for the change and with parts 34 and 36 of this
chapter.'' If a flight guidance system change is categorized as (or is
part of) a product change that is not significant, then the applicable
regulation would be Sec. 21.101(b), which states that ``an applicant
may show that the changed product complies with an earlier amendment of
a regulation required by paragraph (a) of this section.'' The operative
question used to determine whether a change is significant or not is,
``Does the change invalidate the original design and certification
assumptions at the product level?'' If the answer is ``yes,'' an
applicant must comply with the latest regulations, in accordance with
Sec. 21.101(a) unless one of the other exceptions of Sec. 21.101(b)
applies. If the answer is ``no,'' an applicant may show that the
product meets an earlier amendment of the regulation, provided the
earlier amendment has been determined by the FAA to be adequate.
Advisory Circular 21.101-1, Change 1, further discusses how to
evaluate whether a change made to a previously certified product is
significant or not significant. Appendix 1 gives several examples
involving autopilot systems for part 23 and part 25 aircraft. (The
reference to part 23 aircraft is helpful in making a determination of
significance because the examples given in AC 21.101-1 for autopilots
in that section are much more descriptive than those provided in the
part 25 examples.)
The FAA's position on the Changed Product Rule is documented in
Sec. 21.101 and AC 21.101-1. The only time a change may be considered
a ``significant change'' is when a substantially new function is
included to an already certified product. The AC gives the initial
addition of an autoland system as an example of a significant change.
That addition invalidates the original design assumptions and
certification basis for that airplane. Therefore, for the changed
system, an applicant would be required to comply with the regulations
in effect on the date of the application. If, on the other hand, an
applicant is updating an airplane by replacing an old, analog-based
technology autopilot system with a new digital technology autopilot,
that change, by itself is considered not significant. The original
configuration of the airplane has not been changed and the
certification assumptions remain valid. In that case, representative of
a change made under a supplemental type certificate (STC), the
applicant may choose to use a previous amendment of the regulations, as
it applies to the autopilot system. The applicant cannot use an
amendment level in effect any earlier than the time of the original
certification of the product, but it can use one earlier than the ones
in effect at the time of application for the STC.
An exception would be when making a change to the autopilot system
as part of a larger change, such as an update of the flight deck from
analog ``steam gauges'' to a modern flight deck with large displays, an
addition of a flight management system, for example. The overall change
to the airplane may be, in total, categorized as a significant change.
In that case, the regulations in effect on the date of application
would apply to the flight guidance system, as well as to the rest of
the flight deck upgrade.
The FAA provided this guidance to help clarify when a flight
guidance system change may be considered significant for addressing the
Changed Product Rule (Sec. 21.101). However, the FAA did not consider
those potential certification projects in the economic evaluation for
this proposed rule. While a change may be determined significant under
Sec. 21.101, one of the additional exceptions in that rule is that the
applicant may show that complying with the latest requirement is
impractical (Sec. 21.101(b)(3)). One method to show that complying
with the latest requirement is impractical is to show that applying the
latest amendment of the rule would result in added resource
requirements that are not commensurate with safety benefits. That
method is further discussed in paragraph 8c(2)(b) and Appendix 2 of AC
21.101-1.
The FAA assumes that those applicants proposing significant changes
would not use the latest amendment of the flight guidance system rule
if it was determined to be impractical. So, all such applications of
the latest amendment will occur only if it is cost beneficial.
Therefore, the final conclusions from the economic evaluation of this
proposed rule would not be affected by considering the economic impact
of flight guidance system changes. The applicant and the FAA may
consider the question of whether or not complying with the latest
amendment of the rule is impractical during the certification of a
changed product.
What Are the Specific Proposed Changes?
This action would change the name of Sec. 25.1329 and remove Sec.
25.1335. It would revise paragraphs (a) through (h),
[[Page 50245]]
and add new paragraphs (i) through (m) of Sec. 25.1329.
Proposed Sec. 25.1329(a)
Paragraph (a) would be revised to contain the requirements relative
to quick disengagement controls and their placement on both control
wheels for easy accessibility [currently contained in paragraphs (a),
(c) and (d)]. Requirements for quick and easily accessible
disengagement controls for the automatic thrust systems would be added.
These requirements would meet the recognized need for the pilot to be
able to disengage the autothrust system during a high workload
condition without moving his or her hands from the primary controls and
throttle levers, a situation that would hinder task performance. The
phrase ``or equivalent'' would be added after the reference to the
control wheel. This is because some FGS designs would feature flight
deck controls other than the traditional control wheels as the pilot's
primary control mechanism.
Proposed Sec. 25.1329(b)
Paragraph (b) would be revised to add a new requirement that would
address the specific failure of the disconnect switch(es). Paragraph
(b) would mandate that designers and manufacturers must assess what
would happen if a system fails to disengage the autopilot or autothrust
when the pilot manually commands them. That failure would then have to
be addressed in relation to Sec. 25.1309 which requires that a warning
be provided to alert the crew to unsafe system operating conditions,
and to enable them to take appropriate corrective action. The entire
FGS must be evaluated to show compliance with Sec. 25.1309. If the
Sec. 25.1309 assessment asserts that the aircraft can be landed
manually with the autopilot or autothrust system engaged, then this
should be demonstrated during a flight test.
Proposed Sec. 25.1329(c), (d), and (e)
Current paragraphs (c), (d) and (e) would be revised to provide
updated standards for transients for FGS engagement, switching, and
normal and other-than-normal (rare normal and non-normal)
disengagements. The current paragraph (b) addresses the need to limit
transients during engagement, disengagement, and mode changes of the
autopilot system. Current paragraph (b) is technically obsolete and
does not have any bearing on modern autopilot systems. The intent of
the current paragraph (b) regulation would be encompassed in revised
paragraphs (c), (d), and (e).
Use the following definitions when determining compliance with
proposed paragraphs (c), (d), and (e). The definitions of minor and
significant transients are part of the proposed rule text. They are
included here for completeness and understandability.
Transient: A disturbance in the control or flight path of the
airplane that is not consistent with response to flight crew inputs or
current environmental conditions.
Minor transient: A transient that would not significantly reduce
safety margins, and which involves flightcrew actions that are well
within their capabilities involving a slight increase in flightcrew
workload or some physical discomfort to passengers or cabin crew.
Significant transient: A transient that would lead to a significant
reduction in safety margins, a significant increase in flightcrew
workload, discomfort to the flightcrew, or physical distress to
passengers or cabin crew, possibly including non-fatal injuries. The
flightcrew are able to respond to any significant transient without:
1. Exceptional piloting skill, alertness, or strength,
2. Forces greater than those given in Sec. 25.143(c), and
3. Accelerations or attitudes in the airplane that might result in
further hazard to secured or non-secured occupants.
The definition of a ``minor transient'' correlates to the
definition provided in Advisory Circular 25.1309-1A of a ``minor
failure condition.'' Section 25.1309 addresses failure conditions.
Therefore, the term ``minor transient'' used in Sec. 25.1329 cannot be
directly related to the hazard classification used in Sec. 25.1309, as
the transients may or may not have anything to do with failure
conditions. However, the concept for a result of a minor transient can
be correlated to a failure condition that result in a minor hazard in
Sec. 25.1309. Similarly, the definition of a ``significant transient''
correlates to the definition of a ``major failure condition'' defined
in the same AC. A transient larger than significant corresponds to a
hazardous or catastrophic failure condition. In this way, the transient
response of the flight guidance system can be correlated to well-
understood hazard classifications provided by Sec. 25.1309 and AC
25.1309-1A.
The terms ``minor transient'' and ``significant transient,'' are
not absolute, that is, there is not always an unequivocally ``correct/
incorrect'' or ``yes/no'' answer to each item being evaluated. They are
dependent on the specific airplane type being evaluated. An example of
this might be acceleration levels (also known as ``g'' forces)
experienced by the cabin occupants inside a small commuter airplane
during a transient. This transient, based on the criteria above, is
determined to be significant. The ``g'' forces during this transient
were measured to be a certain value. However, an identical ``g'' force
value experienced by a jumbo transport category airplane during a
transient does not necessarily mean that this transient must also be
categorized as a significant transient. Other possible mitigating
factors, such as those listed in the definition of ``significant
transient'' above, should also be included in the evaluation. As with
other terms used in Sec. 25.1329, each case must be assessed
individually, with consideration given to factors considered
appropriate for that specific case.
Proposed paragraphs (c), (d), and (e) have been revised from the
original ARAC proposal. The original proposed paragraphs read as
follows:
(c) Engagement or switching of the flight guidance system, a
mode, or a sensor must not produce a significant transient response
affecting the control or flight path of the airplane.
(d) Under normal conditions, the disengagement of any automatic
control functions of a flight guidance system must not produce any
significant transient response affecting the control or flight path
of the airplane, nor require a significant force to be applied by
the pilot to maintain the desired flight path.
(e) Under other than normal conditions, transients affecting the
control or flight path of the airplane resulting from the
disengagement of any automatic control functions of a flight
guidance system must not require exceptional piloting skill or
strength to remain within, or recover to, the normal flight
envelope.
The FAA has revised the ARAC report for proposed paragraphs (c),
(d), and (e) of Sec. 25.1329. The ARAC proposed paragraphs (c) and (d)
did not allow a significant transient. There was no distinction made
between the lesser transients allowed by proposed paragraphs (c) and
(d) and the more substantial transient allowed by proposed paragraph
(e). Therefore, proposed paragraphs (c) and (d) are revised to not
allow anything more than a minor transient. The definition of ``minor
transient'' is contained in proposed paragraph (c). Proposed paragraph
(e) is revised to refer to the significant transient, and that term is
then defined. These changes allow proposed rule paragraphs (c) and (d)
to be independent of proposed rule paragraph (e).
[[Page 50246]]
Another change that was made to the original ARAC recommendation
was to include the definitions for ``minor transient'' and
``significant transient'' in the rule text. The ARAC preferred to have
these definitions included in the advisory material, rather than
attempt to define very complicated technical terms in a way that can be
included in a rule paragraph. An FAA advisory circular describes an
acceptable means for showing compliance with the requirements. The
guidance is neither mandatory nor regulatory in nature. The AC may
explain or define what specific rule language means. One option would
be to put these definitions in the preamble. This may be acceptable
from a legal standpoint, as the preamble can be used to interpret or
explain the rule language. However, for these particular rule
paragraphs, the FAA finds that the rule will be more clear and
effective if these definitions are included in the rule text. These
concepts are difficult to grasp and do not have universally understood
definitions. The FAA considers that an applicant is better served to
have these terms defined within the rule text, rather than have an
applicant research these terms.
Also, the original proposal for paragraph (e) referred to ``other
than normal conditions.'' This is revised for clarity to ``rare normal
and non-normal conditions.'' The ARAC discussed and accepted these
proposed changes.
Proposed paragraphs (c), (d), and (e) use the terms ``normal
conditions,'' ``rare normal conditions,'' and ``non-normal
conditions.'' ``Rare normal'' refers to challenging environmental
operating conditions that are not normally encountered during routine
service of the airplane. The proposed terms ``normal'' and ``rare
normal'' are not intended to imply a specific probability of these
events occurring. ``Rare normal'' is within the normal operating
envelope of the airplane and encompasses all foreseeable operating
conditions. ``Rare normal'' is intended to make a distinction regarding
the severity of the environmental and operational conditions
encountered, not the probability of encountering those conditions, from
those contained in the ``normal'' conditions. The proposed term ``non-
normal conditions'' refers to failure conditions, both of the FGS and
of other airplane systems. Note that with these definitions, ``rare
normal conditions'' and ``non-normal conditions'' are two different
concepts. That is, ``rare normal'' is not a subset of ``non-normal''
conditions. They can both be grouped under the term ``other than normal
conditions.''
The following table gives examples of what constitutes ``normal,''
``non-normal'' and ``rare normal'' conditions. It does not fully define
every condition that may be encountered during an airplane's life and
clearly categorize that condition. Rather, the table is intended to
explain the intent of the rule language. There will always be, by the
nature of the phenomena involved, some subjectivity to these
categorizations. In addition, the same conditions may affect different
airplane models in very different ways. These differences should be
considered in determining how to characterize the severity of the
conditions discussed below.
The three categories of operating conditions as discussed in this
proposed rule are the following:
------------------------------------------------------------------------
------------------------------------------------------------------------
Normal Conditions
------------------------------------------------------------------------
No failure conditions.... All airplane systems that are associated
with airplane performance are fully
operational. Failures of those systems
could impair the flight guidance
system's ability to perform its
functions.
Light to moderate winds.. Constant wind in a specific direction
that may cause a slight deviation in
intended flight path or a small
difference between airspeed and
groundspeed.
Light to moderate wind Variation in wind velocity as a function
gradients. of altitude, position, or time, which
may cause slight erratic or
unpredictable changes in intended flight
path.
Light to moderate gusts.. Non-repetitive momentary changes in wind
velocity that can cause changes in
altitude and/or attitude to occur, but
the aircraft remains in positive control
at all times.
Light turbulence......... Turbulence that momentarily causes
slight, erratic changes in altitude and/
or attitude (pitch, roll, or yaw).
Moderate turbulence...... Similar to light turbulence but of
greater intensity. Changes in altitude
and/or attitude occur but the aircraft
remains in positive control at all
times.
Light chop............... Turbulence that causes slight, rapid, and
somewhat rhythmic bumpiness without
appreciable changes in altitude or
attitude.
Moderate chop............ Similar to light chop but of greater
intensity. It causes rapid bumps or
jolts without appreciable changes in
aircraft altitude or attitude.
Icing.................... All icing conditions covered by 14 CFR
Part 25, Appendix C, with the exception
of ``asymmetric icing'' discussed under
``Rare Normal Conditions'' below.
------------------------------
Rare Normal Conditions
------------------------------------------------------------------------
Significant winds........ Constant wind in a specific direction
that may cause a large change in
intended flight path or groundspeed, or
cause a large difference between
airspeed and groundspeed.
Significant wind Variation in wind velocity as a function
gradients. of altitude, position, or time, which
may cause large changes in intended
flight path.
Windshear/microburst..... A wind gradient of such magnitude that it
may cause damage to the aircraft.
Large gusts.............. Non-repetitive momentary changes in wind
velocity that can cause large changes in
altitude and/or attitude to occur.
Aircraft may be momentarily out of
control.
Severe turbulence........ Turbulence that causes large, abrupt
changes in altitude or attitude. It
usually causes large variations in
indicated airspeed. Aircraft may be
momentarily out of control.
Asymmetric icing......... Icing conditions that result in ice
accumulations that cause the flight
guidance system, if engaged, to counter
the aerodynamic effect of the icing
conditions with a sustained pitch, roll,
or yaw command that approaches its
maximum authority.
------------------------------
Non-Normal Conditions
------------------------------------------------------------------------
Significant fuel Large variation of the amount of fuel
imbalance. between the two wing tanks (and center
and tail tanks, if so equipped) that
causes the flight guidance system, if
engaged, to counter the aerodynamic
effect of the fuel imbalance with a
pitch, roll, or yaw command that is
approaching maximum system authority.
[[Page 50247]]
Asymmetric lift or drag.. Asymmetric lift between the left and
right wings due to high lift or primary
flight control system failures, or
damage to the aerodynamic surfaces on
wing or tail.
Inoperative engine(s).... Loss of one or more engines that causes
the flight guidance system, if engaged,
to counter the aerodynamic effect of the
difference in thrust with a pitch, roll,
or yaw command that is approaching
maximum system authority.
Loss of one or more Loss of one or more hydraulic systems,
hydraulic systems. down to the minimum amount of remaining
operational systems that the FGS is
certified to operate.
Inoperative ice detection/ Loss of ice detection/protection system
protection system. on an airplane so equipped, in a
situation where the FGS is certified for
operation in icing conditions with that
failure present.
------------------------------------------------------------------------
The intent of these proposed paragraphs is that all FGS function
disconnects, both manual and automatic, result in the least disturbance
to the flight path of the airplane possible. Under more adverse
operating conditions, a larger transient may be impossible for the FGS
by itself to prevent. Proposed paragraph (e) recognizes that the FGS
will not be able to cope as well in these adverse conditions as they
might in the relatively benign, no-failure conditions defined in
proposed paragraph (d). Therefore, the proposed requirement for the
allowable transient upon autopilot disengagement has been relaxed for
these more adverse conditions.
Unless the FGS design uses a specific flight deck alert to let the
flightcrew know of a significant/sustained out-of-trim condition,
compliance with these proposed paragraphs should be assessed with an
assumption of a reasonable response to the upset event by the pilot.
The pilot should be ``hands off'' at the point of autopilot
disengagement. Appropriate time delays for pilot recognition of and
reaction to the failure or anomalous airplane behavior must be added to
the upset recovery maneuver. The time for pilot recognition of an upset
is normally less than one second. Reaction time varies with the phase
of flight. In cruise, climb, descent, and holding, the pilot should not
initiate the recovery action until at least three seconds after the
recognition point. During approach, since the pilot is actively engaged
in monitoring the progress of the airplane, an assumed reaction time of
one second is appropriate.
A flight deck alert (sometimes referred to as ``bark before bite'')
may be used to prompt the flightcrew to mitigate transients and
therefore would be used to show compliance with these proposed
paragraphs. The flight deck alert would notify the crew that an out-of-
trim condition exists that would, if a disconnect were to occur at that
time, cause a significant transient or more. The crew procedure would
be, in response to this alert, to firmly grasp the controls, manually
disconnect the autopilot, and retrim the flight control system as
necessary. Having been alerted, the pilot is aware of the possibility
of a transient and is expecting to counter it when the autopilot
releases control. None of the failure recognition or reaction times
discussed above need be applied during the recovery maneuver if the
airplane is equipped with such an alert.
These proposed paragraphs would cover transients resulting from
engagement, switching, and automatic and manual disengagements of the
flight guidance system. A subset of automatic autopilot disengagement
is when an autopilot disengages because of pilot override. An override
occurs when the pilot or co-pilot applies input to the flight deck
controls without first manually disengaging the autopilot. Autopilot
systems have not always been designed to safely deal with this
situation. Designers assumed the pilot would always manually disengage
the autopilot before making inputs into the flight deck controls if he
or she was not satisfied with the performance of the autopilot. These
proposed regulations have been developed to address the accidents and
incidents that have occurred involving this specific scenario. The
proposed Sec. 25.1329(d) would include transients occurring from
autopilot disconnect caused by pilot override and specifies that under
normal conditions autopilot override must not result in a significant
transient. An automatic autopilot disconnect that results from a pilot
override is a normal event. The system is to be designed for this
occurrence, and should react in a safe, predictable manner. This is not
intended to mean that a pilot override is the normal or preferred
method of disengaging an engaged autopilot. It is just intended to mean
that a pilot override is not a non-normal event.
Note: For the situation involving either an autopilot override
that does not result in automatic disengagement of the autopilot or
the resultant airplane configuration that occurs prior to an
automatic disengagement, see proposed paragraph Sec. 25.1329(l).
Proposed Sec. 25.1329(f)
The proposed paragraph (f) is adapted from the requirements in the
current Sec. Sec. 25.1329(e) and 25.777(b). Proposed paragraph (f)
would state that attitude controls must operate relative to the sense
of motion involved, including the motion effect of the controls and
airplane operation. For cockpit controls, proposed paragraph (f) would
state that the attitude controls must have the direction of motion
plainly indicated on, or adjacent to, each control. The proposed
paragraph (f) would extend the requirement beyond attitude controls to
all command reference controls.
The increasing variety of flight guidance systems can lead to non-
intuitive designs that may promote flightcrew error. Command reference
controls, which are parameters the pilot can set for airspeed, vertical
speed, flight path angle, heading, altitude, and so on, are considered
vulnerable to crew error if the sense of motion and control marking and
the resulting airplane response are not consistent. If a specific FGS
mode is active, changing that particular control position may have an
immediate impact on the heading, altitude, or speed of the airplane.
If, however, the appropriate FGS mode is not active, then manipulation
of this control may only set a referenced target (for example, selected
altitude). That referenced target remains until the control is
manipulated again, or the appropriate FGS mode becomes active. At this
point, the FGS will then actively ``seek'' that target. The FAA chose
the term ``command reference controls'' instead of ``attitude
controls,'' because the use of a term limited specifically to
``attitude'' might lead to confusion in the application of this rule.
Proposed paragraph (f) has been revised from the original ARAC
recommendation. The original proposed paragraph read as follows:
(f) Command reference controls, such as heading select or
vertical speed, must operate consistently with the criteria
specified in Sec. Sec. 25.777(b) and 25.779(a) for cockpit
controls. The function and direction of motion of each control must
be plainly indicated on, or adjacent to, each control if necessary
to prevent inappropriate use or confusion.
After discussion of proposed paragraph (f) within ARAC, the
proposed wording was revised to remove the first sentence. The ARAC
[[Page 50248]]
felt that this information was redundant. The FGS controls must already
comply with Sec. 25.777(b) without restating it in Sec. 25.1329.
Also, the reference to Sec. 25.779(a) was incorrect, because that
paragraph deals with trim tabs, primary controls, and flaps. This
reference was therefore removed.
Proposed Changes to Sec. 25.1329(g)
Proposed paragraph (g) would have the same requirement stated in
current Sec. 25.1329(f). This proposed requirement has been reworded
and reformatted for clarity. It mandates that the system must be
designed so it cannot produce hazardous loads on the airplane or create
hazardous deviations in the flight path. This requirement applies
during normal operation or in the event of a malfunction, assuming
corrective action begins within a reasonable period. The phrase
``within the range of adjustment available to the human pilot''
contained in the original wording of Sec. 25.1329(f) has been removed
from proposed Sec. 25.1329(g). This phrase adds little to the meaning
of the regulation, as there is no real adjustment of the autopilot
system available to the pilot that could affect airplane loads.
Proposed paragraph (g) has been revised from the original ARAC
working group proposal. The original proposed paragraph read as
follows:
(g) Under any condition of flight appropriate to its use, the
Flight Guidance System must not:
Produce unacceptable loads on the airplane (in accordance
with Sec. /JAR 25.302), or
Create hazardous deviations in the flight path.
This applies to both fault-free operation and in the event of a
malfunction, and assumes that the pilot begins corrective action
within a reasonable period of time.
The first ARAC recommendation referred to proposed Sec. 25.302
titled ``Interaction of systems and structure.'' During the FGS
Harmonization Working Group activities, the ARAC Structures
Harmonization Working Group was developing proposed Sec. 25.302. The
FAA planned to issue and publish these two proposed rules (Sec. Sec.
25.1329 and 25.302) concurrently in the Federal Register. The FAA has
since placed proposed Sec. 25.302 on hold because of other rulemaking
priorities. Therefore, the working group revised their proposed
paragraph (g) to remove the reference to proposed Sec. 25.302. This
change, with minor editing and reformatting, removes the current text
of paragraph (f) and adds it to proposed paragraph (g).
This proposed change does not affect the harmonization effort
between the FAA and JAA. The JAA version (which is the original ARAC
working group proposal) references the new material in JAR 25.302, and
it defines exactly how to assess what is an ``unacceptable load.'' With
the current Sec. 25.1329(f), an assessment of compliance must actually
come from the analyses and testing required by Sec. 25.1309. This will
also be true of proposed Sec. 25.1329(g). Therefore, the intent of the
JAA and proposed FAA rules remains identical. The FAA proposed Sec.
25.1329(g) would depend upon compliance with Sec. 25.1309 for
evaluating the interaction of the FGS and the airplane structure.
One member of the working group expressed a concern that the FAA
may assume a mandatory compliance method, and that flight testing would
be the only method acceptable to show compliance with some proposed
paragraphs of Sec. 25.1329. Of particular concern is flight guidance
system operation in icing conditions. Section 25.1329 proposed
paragraphs (d), (e), and (g) do not specify a compliance method. They
simply set forth design criteria. Proposed AC 25.1329-XX would provide
guidance for one method of compliance. However, as with all advisory
material, that proposed guidance would be one acceptable means, but not
the only means for demonstrating compliance with this proposed
regulation. Public comments concerning proposed AC 25.1329-XX are
invited by separate notice published elsewhere in this issue of the
Federal Register.
These paragraphs are not intended to require proof of compliance
for amended type certificates (ATC) and supplemental type certificates
(STC) solely through flight tests, especially when relevant service
history data exists. An analysis of such data, and its determination of
applicability to a given project, may be used by the applicant to meet
the proposed requirement(s). Regarding certain environmental factors
such as icing, and for ATC and STC projects (for example where an
existing, approved autopilot is replaced by another autopilot),
conducting a review of field history data may help in determining the
extent of required flight testing. If the applicant can show that there
is a lack of autopilot-related accidents and/or incidents in the icing
environment involving a type certificated airplane, it may be possible
to show compliance without needing additional flight tests with ice
shapes or in natural icing. The responsible aircraft certification
office must approve the applicant's justification.
Proposed Sec. 25.1329(h)
This would be a new requirement for speed protection. It would
include both high and low speed protection. It would require that when
the flight guidance system is in use, a means must be provided to avoid
excursions beyond an acceptable margin from the speed range of the
normal flight envelope. If the airplane experiences an excursion
outside this range, the flight guidance system must not provide
guidance or control to an unsafe speed. The phrase ``to an unsafe
speed'' is intended to mean that the flight guidance system should not
control or provide guidance that would eventually lead to an
aerodynamic stall or a speed that is in excess of the maximum operating
speed, regardless of the maneuver being conducted at the time.
The FAA Human Factors Team completed a report in 1996 that
evaluated flightcrew/flight deck automation interfaces. The Background
section of this document contains a summary of that report. One of the
Team's conclusion was that during FGS operation, flightcrew awareness
of, or attention to, airspeed may not be sufficient to provide timely
detection of unintended speed changes that could possibly compromise
safety. In addition, in certain conditions, the current modes of the
autopilot and/or autothrust may not be designed to prevent speed
excursions outside the normal range.
This proposed requirement would prevent unwanted airspeed
excursions. The preferred implementation is for the FGS to
automatically provide control and/or guidance to avoid these
excursions. However, an implementation providing increased awareness of
airspeed and/or alerts for immediate crew recognition and intervention
of a potential airspeed excursion may also be an acceptable means of
complying with this regulation. Proposed AC 25.1329-XX would provide
guidance for several methods of compliance. However, as with all
advisory material, that proposed guidance would be one acceptable
means, but not the only means, for demonstrating compliance with this
proposed regulation. Public comments concerning proposed AC 25.1329-XX
are invited by separate notice published elsewhere in this issue of the
Federal Register.
When applying these proposed regulations to amended type
certification or supplemental type certification programs, it may not
always be possible to have the updated FGS be in compliance with this
proposed paragraph without updating
[[Page 50249]]
some other, non-flight-guidance systems. Some of these previously
certified airplanes, particularly the smaller part 25 airplanes, may
not be fully equipped with interfacing airplane systems (specifically,
angle-of-attack sensors) that are normally required to implement fully
a speed protection function in the flight guidance system. It is the
intent of this proposed rule that, with programs of this nature and
given limitations such as the one discussed above, the applicant design
the best system possible that meets the intent of this proposed
regulation. However, an applicant for an STC or ATC flight guidance
system update would not be required to also install angle-of-attack
sensors to support the speed protection function. To require that could
possibly make the entire STC/ATC program so expensive that the
applicant might not choose to update an earlier technology autopilot
with the latest technology available. Such a decision would result in
the loss of all other substantial increases in safety that otherwise
would have been gained if the applicant had chosen to continue with
that STC/ATC program.
Proposed Sec. 25.1329(i)
This proposed paragraph (i) would have the same text as current
paragraph (h), requiring indication of current mode of operation. It
would also specify that these indications must include any armed modes,
transitions, and reversions. It would add a statement of the safety
objective to minimize crew errors and confusion. It would address
logical grouping and presentation of mode indications and controls for
the sake of visibility from each pilot position and for flightcrew
awareness of active modes and mode changes. This proposed paragraph
would also incorporate the current Sec. 25.1335 text requiring
indication of the mode of operation of any flight director.
Studies have shown that lack of sufficient flightcrew awareness of
modes, transitions, and reversions is a key safety vulnerability. This
paragraph would provide the regulatory basis for several provisions of
the proposed advisory circular related to enhanced flightcrew awareness
of flight guidance system active and armed modes. It would also address
the need for awareness of changes in flight guidance system behavior
that may otherwise be unanticipated by the flightcrew.
Proposed Sec. 25.1329(j)
This proposed requirement for a visual and auditory warning of
autopilot disengagement would be adopted from the current JAR
25.1329(i) and does not exist in the current 14 CFR part 25. This JAR
requirement is appropriate because disengagement of the autopilot, for
whatever reason, makes timely flightcrew intervention necessary to
assume manual control of the airplane. Timely, in this case, is meant
to specify a period suitable for the specific situation, without
mandating a specific time period within the rule itself. The proposed
requirement that the warning look and sound distinct from other cockpit
warnings is meant to provide unequivocal awareness that the flightcrew
must assume manual control of the airplane.
The term ``warning'' is defined in FAA Advisory Circular 25-11,
Section 10. Current FAA harmonization and rulemaking activity regarding
to Sec. 25.1322, ``Warning, caution, and advisory lights,'' when
issued, would result in the definition of this term within the rule
itself.
The original ARAC recommendation contained the wording ``a visual
and aural warning.'' The working group membership discussed that
wording and changed it to ``a warning (visual and aural).'' This would
ensure there was no confusion by the reader that there are two
components to a warning, one visual and one aural.
Proposed Sec. 25.1329(k)
This proposed paragraph is a new requirement. It would mandate
providing a ``caution'' to each pilot when the autothrust has been
disengaged.
The flightcrew needs to be aware that the autothrust system has
disengaged, so they do not continue to expect the desired speed control
to be provided. Normally, however, autothrust disengagement would not
require immediate thrust control changes by the flightcrew. Therefore,
the less specific ``caution'' rather than ``warning'' is required.
The term ``caution'' is defined in FAA Advisory Circular 25-11,
Section 10. Also, current FAA harmonization and rulemaking activity
regarding Sec. 25.1322, ``Warning, caution, and advisory lights,''
when issued, would result in the definition of this term within the
rule itself.
Proposed Sec. 25.1329(l)
This new paragraph requires that flightcrew override of the
autopilot must not create a potential hazard when the flightcrew
applies an override force to the flight controls. As stated previously
in the discussion on Sec. 25.1329(d), an override occurs when the
pilot or first officer applies input to the flight deck controls
without first manually disengaging the autopilot. Pilot override may
not always result in autopilot disengagement. If the autopilot does not
disengage during override, the result might be an out-of-trim condition
(for example, a horizontal stabilizer/elevator jackknife, where the
surfaces are aerodynamically opposing each other). This could result in
a significant transient and/or loss of control if the autopilot were to
be disconnected or if the pilot were to suddenly release the force
being applied to the flight deck controls while the airplane is in this
configuration. Several accidents and incidents have occurred after
flightcrew override of the autopilot. Nevertheless, it is not advisable
to prohibit flightcrew override in all cases, because override might be
the last resort for the flightcrew to regain control of the airplane in
certain abnormal (failure) conditions or in an emergency avoidance
maneuver.
This rule paragraph is changed from the original ARAC
recommendation. That proposed rule language used the term ``unsafe
condition.'' The FAA revised this rule paragraph to use the term
``potential hazard'' instead of ``unsafe condition.'' The reason behind
this revision is that the term ``unsafe condition'' has a very definite
meaning within the context of FAA regulations. Under 14 CFR part 39, we
issue airworthiness directives when we determine that an ``unsafe
condition'' is likely to exist or develop on other products of the same
type design. Proposed paragraph (l) addresses a specific type of
hazard, and so the use of the broad term ``unsafe condition,'' with its
many implications under part 39, is inappropriate. Also, Sec.
21.21(b)(2) prohibits certification of any aircraft which contains
unsafe design features, so the original wording of this paragraph would
be redundant of the part 21 rule. Therefore, the FAA revised this rule
paragraph to refer to ``potential hazard'' instead.
This preamble does not attempt to give a complete definition of the
term ``potential hazard.'' The FAA cannot define all airplane
configurations that should be considered potentially hazardous that may
occur during a flightcrew override. To do so would be too restrictive,
as this would assume the FAA is able to fully define all hazardous or
potentially hazardous conditions that might result for all current and
future FGS and airplane designs. What this term means is anything that
could significantly reduce safety margins or invalidate any assumption
or premise made by the System Safety Assessment.
The term ``potential hazard'' used above is intended to describe
possible
[[Page 50250]]
future hazards if another event were to happen with the airplane in a
specific configuration during the override. That event might be an
autopilot disengagement, the pilot abruptly releasing the controls, or
another failure that occurs during the flightcrew override. Therefore,
the term ``potential hazard'' is not fully defined. Rather, a
description of the concept has been used to explain what is meant and
how compliance with this paragraph could be demonstrated. Proposed
paragraph (l) should be evaluated under ``normal conditions'' discussed
elsewhere in this document.
Proposed Sec. 25.1329(m)
This new paragraph requires that the flightcrew be able to move the
thrust levers during autothrust operation without using excessive
force. It requires that the autothrust response to flightcrew override
must not create a potential hazard.
This rule paragraph is changed from the original ARAC
recommendation. That proposed rule language used the term ``unsafe
condition.'' For the reasons described for Sec. 25.1329(l), the FAA
revised this rule paragraph to use the term ``potential hazard''
instead of ``unsafe condition.'' We intend ``potential hazard'' under
this paragraph to have the same meaning as under Sec. 25.1329(l).
Examples of potentially hazardous situations include a rapid and
unexpected change in the pitch attitude of the airplane (because of a
change in engine thrust on an airplane with underslung engines) or an
uncontrolled increase or decrease in the thrust settings.
As under Sec. 25.1329(l), the term ``potential hazard'' is used to
describe possible future hazards if another event were to happen with
the airplane in a specific configuration during the override. That
event might be an autothrust system disengagement, the pilot abruptly
releasing the controls, or another failure that occurs during the
flightcrew override. Therefore, the term ``potential hazard'' is not
fully defined. Rather, a description of the concept has been used to
explain what is meant and how compliance with this paragraph could be
demonstrated.
There may be times when the flightcrew needs to immediately change
thrust without first manually disengaging the autothrust system. There
may be cases when the normal controls for disengaging the autothrust
system have failed and the ability to override the autothrust system is
the only means available to manually control thrust.
Proposed Sec. 25.1335
Current Sec. 25.1335 requires that if a flight director system is
installed, its current mode of operation must be indicated to the
flightcrew. The text of Sec. 25.1335 would be removed and added to
proposed Sec. 25.1329(i). Section 25.1335 would be removed from the
CFR.
What Comments Were Received From the ARAC in Response to the Proposal?
A ``Fast Track Harmonization'' rulemaking project provides for a
formal review of the draft NPRM, if requested, by the ARAC. The ARAC
did not request a formal review.
A meeting with the FAA, JAA, and FGS working group was held in
Toulouse, France, in February 2004. Discussions concerning disposition
of comments on the JAA NPA for JAR 25.1329 prompted the FAA to request
comments on the NPRM from attending ARAC FGS working group members. The
FAA received three comments. Although ARAC did not request a review of
the NPRM, the intent of an ARAC review has been fulfilled.
The JAA proposed to adopt ARAC's recommendation without change.
While we revised the proposed regulatory text in this NPRM from ARAC's
recommendation to clarify certain provisions, we have confirmed that
the substance and intent are the same. We therefore consider this
proposal to be fully harmonized with the JAA's because the rules would
have the same effect.
The following comments represent those received informally from the
FGS working group members at the Toulouse meeting.
FAA Response to Comment on the Term ``Rare Normal Condition,''
Proposed Paragraph (e): One FGS working group member disagreed with a
statement included in the proposed preamble language that the term
``rare normal condition'' is intended to make a distinction regarding
the severity of the environmental and operational conditions
encountered, not the probability of encountering those conditions. The
commenter asserted that the HWG did imply to infer probability when
discussing ``rare normal'' conditions.
FAA Disposition of Comment: The FAA disagrees with this comment.
``Rare normal conditions'' cannot imply anything about the probability
of encountering those conditions for the following reasons. Some icing
conditions (possibly severe) may be encountered on a regular basis,
perhaps daily. This is especially true, for example, given a specific
daily operation in some extreme weather conditions (for example,
northern latitudes in stormy conditions in autumn or winter).
Therefore, in the probabilistic sense of the word, it may not be
``rare'' to encounter these severe conditions.
The real concern is that the Flight Guidance System must be able to
handle these adverse environmental conditions according to the proposed
regulations whenever they occur, regardless of how often they occur.
Proposed paragraphs (d) and (e) would make a distinction based on the
severity of the condition encountered, not the probability of
encountering that condition. Proposed paragraph (e) would allow some
degradation of system performance for the more severe environmental
conditions encountered than those allowed by paragraph (d). The
probability of encountering those conditions is not an issue.
Changes: No change was made to the NPRM because of this comment.
FAA Response to Comment on the Proposed Preamble Discussion of
Pilot Override: One FGS working group member disagreed with the
discussion in the proposed preamble that states, ``An automatic
autopilot disconnect due to a pilot override is a normal condition. The
system is to be designed for this occurrence. It is not considered a
non-normal event.'' The commenter strongly disagreed with the FAA
statement that an override is a normal condition. The commenter
expressed concern that the FAA and applicants would take this to mean
that an override was a normal way to ``disengage an autopilot.''
FAA Disposition of Comment: The FAA disagrees with the main point
of this comment. If a pilot override was classified as a non-normal
event, proposed paragraph (e) would allow a significant transient to
result because of the override. The override would be addressed with
this proposed rule. Several accidents and incidents have occurred
because of a pilot override of an engaged autopilot. This proposal
would require a transient resulting from an override to be as benign as
possible [in other words, to be covered by proposed paragraph (d)].
Classifying an override as a ``non-normal condition'' would be contrary
to this intent.
One relevant point is that an override is not a ``condition.'' It
is an action taken by the flightcrew. It may be in response to a system
failure, a reflexive reaction by the pilot to avoid oncoming traffic,
or even a desire to assist an engaged autopilot in leveling off or
slowing down a descending airplane without first manually disengaging
the
[[Page 50251]]
system. A ``condition,'' based on proposed Sec. 25.1329 text and the
proposed AC 25.1329-XX, is due to a system failure or adverse
environmental circumstance, or (in the case of a normal condition) the
lack of failures or adverse environmental circumstances. A pilot action
is therefore not a ``condition.''
Changes: The FAA agrees that the proposed preamble wording should
be revised. The revised NPRM would state that an override is a normal
event rather than a normal condition, and make it clear that an
override is not the usual or preferred method to disengage an engaged
autopilot. We have revised the NPRM.
FAA Response to Comment on the Term ``Hazardous Conditions,''
Proposed Paragraph (g): One FGS working group member stated that the
revision made to proposed paragraph (g) did not fully define flight
guidance malfunction criteria, and that the term ``hazardous
conditions'' is confusing. The commenter stated that this could be
misconstrued as the AC 25.1309 definition of ``hazardous.'' The
commenter suggests that proposed paragraph (g) should ``invoke the
concept that the severity of the malfunction is inversely proportional
to the probability of occurrence.'' This would relate flight guidance
malfunctions to the following Sec. 25.1309 standards:
A malfunction, which exceeds structural limits, should be
Extremely Improbable.
A malfunction, which exceeds limit loads or results in
serious or fatal injury to a relatively small number of occupants,
should be Extremely Remote.
A malfunction which results in physical distress, possibly
including injuries should be Remote.
FAA Disposition of Comment: The commenter has two comments. First,
the commenter finds the use of the term ``hazardous'' confusing. The
FAA disagrees with this comment. The proposed use of hazardous in
paragraph (g) is very similar to the use of hazardous in the current
Sec. 25.1329. Proposed paragraph (g) would invoke the concept of the
Sec. 25.1309 definition of hazardous.
Note: The only difference between current paragraph Sec.
25.1329(f) and the ARAC recommendation is the removal of the
language, ``within the range of system adjustments available to the
human pilot.'' This language is removed because it is confusing and
technically obsolete.
Second, the commenter states that proposed paragraph (g) should
``invoke the concept that the severity of the malfunction is inversely
proportional to the probability of occurrence.'' The FAA does not
consider this necessary. The autopilot system being certified under
proposed Sec. 25.1329(g) must also meet the requirements of Sec.
25.1309. Therefore, this concept is already covered by that regulation
and does not need to be repeated in proposed Sec. 25.1329(g).
Changes: The FAA does not agree. No change will be made to proposed
paragraph (g).
What Is the Effect of the Proposed Standard Relative to the Current
Regulations?
The proposed rule expands the scope of Sec. 25.1329 beyond
autopilot systems to include requirements for flight director and
autothrust. These functions are increasingly integrated into the same
equipment. The fundamental principles for engagement, disengagement,
and flightcrew awareness of changes in system operation, apply to each
of the functions in a similar manner. The NTSB has recommended changes
for enhanced flightcrew awareness of system operation and changes in
airplane condition. Often, during FGS operation, the flightcrew is
insufficiently aware of changes in attitude, airspeed, trim, and so
forth that could adversely affect flight safety. This proposed rule and
proposed advisory circular would increase the level of safety through
improved system indications, annunciations, and speed protection. It
would also encourage modern airplane flight deck standardization, which
would also improve safety when flightcrew personnel pilot more than a
single airplane type.
What Is the Effect of the Proposed Standard Relative to the Current
Regulations?
The effect of the proposed change on current industry practice
would be that:
Operating differences between different airplane types
would be minimized.
Manufacturers would be required to assess system
transients during disengagement of the autopilot systems.
Flight guidance systems would be required to address the
issue of speed protection.
Certification standards for flight guidance systems for
the U.S. and Europe would be harmonized.
Other design enhancements would be incorporated to address
system vulnerabilities that have been highlighted by several NTSB
safety recommendations and FAA studies.
What Other Options Have Been Considered and Why Were They Not Selected?
The following is a discussion of major alternatives considered
during the rulemaking activity, and the reasons each proposal was
ultimately rejected.
Envelope FAA and JAA requirements without adding new
requirements.
Pro: Enveloping the FAA and JAA rules (adopting the more rigorous
requirements of each) would have been a much simpler rulemaking task
and an easier adjustment for industry. It would have harmonized the
requirements and simplified bilateral validation programs.
Con: The existing requirements are out of date. They do not
adequately address safety issues related to current designs and the
anticipated direction of future designs. Service history and studies
show that previous assumptions about flightcrew awareness of the
airplane during autopilot operation are out of date as well. Flightcrew
reliance on automated flight control systems has increased markedly
since the current regulations were issued. The FAA Human Factors Team
report, many NTSB safety recommendations, and other information (noted
earlier in this document) point out the need to enhance flightcrew
awareness of autopilot and guidance system operation. Newer designs
enable functions that were not possible for automated systems when the
current regulations were developed. They integrate the functions of
many related systems and are far more complex than ``first or second
generation'' systems based on analog technology. The newer designs also
tend to be more complex from the crew's perspective, and vulnerable to
flightcrew confusion over mode behavior and transitions. Standards
cannot be effective if they simply address a particular avionics
system; they need to address the functionality, regardless of which
systems host the functionality. For reasons like these, the simple
adoption of current requirements would not provide adequate safety
standards.
Define the scope of the rule to include all automatic
control and guidance systems including FMS, yaw damping, integrated
energy management, and so forth.
Pro: If mandated, a fully integrated system such as the one
described above would provide increased safety because complex
interactions between systems would be transparent to the flightcrew.
All human-machine interfaces would be consistent among the various
functions. All functionality would be totally
[[Page 50252]]
integrated and would not (if designed correctly) result in a situation
where the individual system ``expectations'' conflicted with each
other.
Con: This activity was considered out of the scope of the ARAC
tasking, although such a system may be desirable for future
development. Many of the functions listed are not considered part of a
flight guidance system, and would therefore require coordination and
agreement on appropriate language addressed in several other ARAC
tasks. This would jeopardize completion of this rulemaking within a
reasonable time. Also, the cost of such a system would most likely be
prohibitive when applied to some of the smaller part 25 category
aircraft.
Require full flight envelope protection, that is,
protections provided by the FGS, available in all flight phases and
operational modes, that would not allow the airplane to exceed certain
predefined speeds, pitch and bank angles, ``g'' maneuvers, and so
forth, or would alert the pilot to that these limits were being
exceeded.
Pro: Enhanced safety in all flight phases and flight guidance
system modes.
Con: The cost/benefit return was not sufficient, because the
primary focus in accidents and incidents is speed rather than full
flight envelope. Therefore, the most cost-effective approach would be
requiring speed protection only. Also, full flight envelope protection
is more a function of design of the overall flight control system of
the airplane, and not the flight guidance system.
Require that speed protection always involve some form of
automatic autothrust ``wakeup,'' that is, automatic autothrust system
engagement from a disengaged state.
Pro: Enhance safety by having low speed protection thrust control
engage automatically, even if the autothrust system is not currently
active.
Con: Many airplanes are not equipped with an autothrust system, so
those airplanes would not benefit from any regulation of this type.
Also, many autothrust systems must be manually armed by manipulating a
switch before the automatic function is allowed to become active. This
is a necessary safeguard in some systems to prevent inadvertent
activation when it could be hazardous (on the ground, for example).
System designs that require the manual switch before the system can be
activated would make the design of such a ``wake up'' feature very
difficult and costly to implement. The ARAC decided that the proposed
rule and AC adequately address low speed awareness and protection
without requiring this feature.
Who Would Be Affected by the Proposed Change?
Avionics manufacturers would incur the added expense and time of
designing and developing systems with extra features that would meet
new proposed regulations (high and low speed protection, for example).
Airplane manufacturers would be impacted as well. Operators could be
affected by additional training requirements and the need to update
equipment and documentation.
The proposed rule would apply to all new type certification (TC)
programs. There would be added development costs incurred by both
avionics and airplane manufacturers to meet these new regulations. When
the NPRM is issued and the proposed requirements become known, the new
features could be incorporated as part of the basic design.
The proposed rule, if applied to supplemental type certification
(STC) or amended type certification (ATC) programs, would update
previously certified airplanes and ATC programs. If the changes are
``cut-in'' to an existing production line, then new functionality of
the airplane could be required (speed protection, for example) and
therefore added costs could be incurred. These added costs would be
dependent upon the configuration of the airplane being modified and the
functionality of the system required to be installed in that airplane.
The STC/ATC applicant could incur costs to modify the airplane, for
example, to add additional sensors, and wiring. There would be
increased costs associated with, for example, equipment, development,
and flight test. Both the avionics vendor and the STC/ATC applicant
would incur increased costs to cover extended development and
certification of the modified airplane. The operator and airplane
manufacturer could incur increased costs if part of a fleet is required
to meet the latest regulations. The operator might elect to bring its
entire fleet up to the latest standards for fleet commonality and
training considerations.
Is Existing FAA Advisory Material Adequate?
No, the existing advisory material is not adequate. The existing
advisory material would be made obsolete by this proposed rule. The
ARAC developed a proposed harmonized advisory circular, proposed AC
25.1329-XX. Public comments concerning proposed AC 25.1329-XX are
invited by separate notice published elsewhere in this issue of the
Federal Register.
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. We have determined that there
are no new information collection requirements associated with this
proposed rule.
International Compatibility
In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA 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 correspond to these proposed regulations.
What Regulatory Analyses and Assessments Has the FAA Conducted?
Regulatory Evaluation Summary, Regulatory Flexibility Determination,
International Trade Impact Assessment, and Unfunded Mandates Assessment
This portion of the preamble summarizes the FAA's analysis of the
economic impacts of this NPRM, consistent with various Federal
directives and orders. Each Federal agency proposing a regulation must
make a reasoned determination that the benefits justify the costs, and,
separately, assess the effects on small entities, international trade,
and whether or not the proposal imposes a Federal mandate resulting in
a total expenditure of $100 million or more in any one year (an
``unfunded mandate assessment''). In conducting these analyses, the FAA
has determined that the proposal:
(1) Has benefits that justify its costs;
(2) Is not a significant regulatory action;
(3) Would not have a significant impact on a substantial number of
small entities;
(4) Is in compliance with the Trade Agreement Act; and
(5) Does not impose an unfunded mandate of $100 million or more, in any
one year, on State, local, or tribal governments, or on the private
sector.
The FAA has placed these analyses in the docket and summarized them
below.
Total Costs and Benefits of This Rulemaking
Estimated discounted costs--
Small part 25 certificated airplanes (large business jets): $97
million.
[[Page 50253]]
New-production part 25 large transport category airplanes already
meet the proposed requirements.
Estimated discounted benefits--
Small part 25 certificated airplanes (large business jets).
Qualitative Benefits Analysis--NPRM may avert four accidents with a
value equivalent to discounted costs of $97 million.
Who Is Affected by This Rulemaking?
Manufacturers of small part 25 airplanes incur costs.
Occupants in affected airplanes receive safety benefits.
Assumptions and Standard Values
Discount rate: 3%.
Period of analysis: 2005-2040. Costs, 2005-2015 (one year
of certification costs followed by ten years of production costs; there
are no operating costs incurred as a result of the revisions).
Benefits, 2007-2040 (based on 25-year operating lives of newly-
certificated airplanes, all of which will be produced between 2006-
2015).
Value of statistical fatality avoided: $3 million.
The proposed rule would significantly reduce occurrence of
autopilot-related accidents in part 25 business jets.
Alternatives Considered
JAA/FAA harmonized standards were selected for this NPRM because of
both the assessed improvements in operation of autopilot systems and
the potential cost savings resulting from harmonization of FAA and JAA
requirements.
Costs of This Rulemaking
Certification costs (non-recurring) equal $530,000 for each of four
type-certifications. Recurring costs equal $52,000 for each airplane
produced. Non-recurring and recurring costs total $116.520 million, or
$96.554 million at present value. Present value costs are based on a 3%
discount factor, which is allowed by the Office of Management and
Budget where a study period covers 25 or more years; the combined
costs-benefits period of analysis covers 36 years--2005 to 2040.
Benefits of This Rulemaking
The FAA has estimated the minimum levels of averted losses, in
terms of avoided fatalities and airplane damage (each accident is
valued at $40 million, i.e., ten fatalities at $3 million each plus $10
million airplane replacement value) that would be necessary to offset
the estimated compliance costs. The FAA has determined that the
proposed rule would be cost-beneficial if four accidents were averted
in the 34-year benefits period. There were four accidents or serious
incidents involving business jets over a recent 20-year period (1983-
2002); thus, over the future 34 years evaluated in this benefits'
analysis, in the absence of a rule, one could expect nearly twice that
number, or seven. Although it is not certain that the earlier events
could have been prevented by the proposed autopilot changes (or, how
many of any potential future accidents would, in fact, be
catastrophic), the expected prevalence of more sophisticated autopilot
systems in business jets, combined with the occurrence of serious
accidents involving large transports (these provided the impetus for
this rulemaking--see full regulatory evaluation), mandates regulatory
action. For these reasons, the FAA finds this proposed rule to be cost-
beneficial.
Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (RFA) requires that agencies
perform a review to determine whether a proposed or final rule will
have a significant economic impact on a substantial number of small
entities. The proposed rule would affect manufacturers of part 25
business jets produced under future new type-certificates. For
manufacturers, a small entity is one with 1,500 or fewer employees.
None of the part 25 manufacturers have 1,500 or fewer employees.
Based on the above, the FAA certifies that the proposed rule would
not have a significant economic impact on a substantial number of small
entities. The FAA invites comments on the estimated small entity impact
from interested and affected parties.
International Trade Impact Assessment
The Trade Agreement Act of 1979 prohibits Federal agencies from
engaging in any standards or 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.
In accordance with the above statute, the FAA has assessed the
potential effect of this proposed rule for airplanes produced under the
affected FAR part. This rulemaking is consistent with the Trade
Agreement Act since JAA and FAA international standards are the basis
for this rulemaking.
Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (the Act)
requires each Federal agency, to the extent permitted by law, to
prepare a written assessment of the effects of any Federal mandate in a
proposed or final agency rule that may result in the expenditure by
State, local, and tribal governments, in the aggregate, or by the
private sector, of $100 million or more (adjusted annually for
inflation) in any one year. The FAA determines that this proposed rule
does not contain a significant intergovernmental mandate.
What Other Assessments Has the FAA Conducted?
Executive Order 13132, Federalism
The FAA has analyzed this proposed rule under the principles and
criteria of Executive Order 13132, Federalism. We 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 of proposed
rulemaking would not have federalism implications.
Plain English
Executive Order 12866 (58 FR 51735, Oct. 4, 1993) requires each
agency to write regulations that are simple and easy to understand. We
invite your comments on how to make these proposed regulations easier
to understand, including answers to questions such as the following:
Are the requirements in the proposed regulations clearly
stated?
Do the proposed regulations contain unnecessary technical
language or jargon that interferes with their clarity?
Would the regulations be easier to understand if they were
divided into more (but shorter) sections?
Is the description in the preamble helpful in
understanding the proposed regulations?
Please send your comments to the address specified in the ADDRESSES
section.
Environmental Analysis
FAA Order 1050.1D defines FAA actions 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.
[[Page 50254]]
Regulations That Significantly Affect Energy Supply, Distribution, or
Use Impact
The FAA has analyzed this NPRM under Executive Order 13211, Actions
Concerning Regulations that Significantly Affect Energy Supply,
Distribution, or Use (May 18, 2001). We have determined that it is not
a ``significant energy action'' under the executive order because it is
not a ``significant regulatory action'' under Executive Order 12866,
and it is not likely to have a significant adverse effect on the
supply, distribution, or use of energy.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements, Safety, Transportation.
The Proposed Amendment
In consideration of the foregoing, the Federal Aviation
Administration proposes to amend Part 25 of Chapter 1 of Title 14, Code
of Federal Regulations, as follows:
PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES
1. The authority citation for part 25 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702 and 44704.
2. Revise Sec. 25.1329 to read as follows:
Sec. 25.1329 Flight guidance system.
(a) Quick disengagement controls for the autopilot and autothrust
functions must be provided for each pilot. The autopilot quick
disengagement controls must be located on both control wheels (or
equivalent). The autothrust quick disengagement controls must be
located on the thrust control levers. Quick disengagement controls must
be readily accessible to each pilot while operating the control wheel
(or equivalent) and thrust control levers.
(b) The effects of a failure of the system to disengage the
autopilot or autothrust functions when manually commanded by the pilot
must be assessed in accordance with the requirements of Sec. 25.1309.
(c) Engagement or switching of the flight guidance system, a mode,
or a sensor must not cause a transient response of the airplane's
flight path any greater than a minor transient. For purposes of this
section, a minor transient is an abrupt change in the flight path of
the airplane that would not significantly reduce airplane safety, and
which involves flightcrew actions that are well within their
capabilities involving a slight increase in flightcrew workload or some
physical discomfort to passengers or cabin crew.
(d) Under normal conditions, the disengagement of any automatic
control function of a flight guidance system must not cause a transient
response of the airplane's flight path any greater than a minor
transient.
(e) Under rare normal and non-normal conditions, disengagement of
any automatic control function of a flight guidance system must not
result in a transient any greater than a significant transient.
Significant transients may lead to a significant reduction in safety
margins, an increase in flightcrew workload, discomfort to the
flightcrew, or physical distress to the passengers or cabin crew,
including non-fatal injuries. Significant transients do not require, in
order to remain within or recover to the normal flight envelope, any of
the following:
(1) Exceptional piloting skill, alertness, or strength.
(2) Forces applied by the pilot which are greater than those
specified in Sec. 25.143(c).
(3) Accelerations or attitudes in the airplane that might result in
further hazard to secured or non-secured occupants.
(f) The function and direction of motion of each command reference
control, such as heading select or vertical speed, must be plainly
indicated on, or adjacent to, each control if necessary to prevent
inappropriate use or confusion.
(g) Under any condition of flight appropriate to its use, the
flight guidance system must not produce hazardous loads on the
airplane, nor create hazardous deviations in the flight path. This
applies to both fault-free operation and in the event of a malfunction,
and assumes that the pilot begins corrective action within a reasonable
period of time.
(h) When the flight guidance system is in use, a means must be
provided to avoid excursions beyond an acceptable margin from the speed
range of the normal flight envelope. If the airplane experiences an
excursion outside this range, the flight guidance system must not
provide guidance or control to an unsafe speed.
(i) The flight guidance system functions, controls, indications,
and alerts must be designed to minimize flightcrew errors and confusion
concerning the behavior and operation of the flight guidance system.
Means must be provided to indicate the current mode of operation,
including any armed modes, transitions, and reversions. Selector switch
position is not an acceptable means of indication. The controls and
indications must be grouped and presented in a logical and consistent
manner. The indications must be visible to each pilot under all
expected lighting conditions.
(j) Following disengagement of the autopilot, a warning (visual and
auditory) must be provided to each pilot and be timely and distinct
from all other cockpit warnings.
(k) Following disengagement of the autothrust function, a caution
must be provided to each pilot.
(l) The autopilot must not create a potential hazard when the
flightcrew applies an override force to the flight controls.
(m) During autothrust operation, it must be possible for the
flightcrew to move the thrust levers without requiring excessive force.
The autothrust must not create a potential hazard when the flightcrew
applies an override force to the thrust levers.
Sec. 25.1335 [Removed].
3. Remove Sec. 25.1335.
Issued in Renton, Washington, on July 28, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-18351 Filed 8-12-04; 8:45 am]
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