Federal Register / Vol. 66, No. 42 / Friday, March 2, 2001 / Notices 13113

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Dated: February 20, 2001.

Joseph J. Angelo,

Director of Standards, Marine Safety and

Environmental Protection.

[FR Doc. 01–5115 Filed 3–2–01; 8:45 am]

BILLING CODE 4910–15–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

[Policy Statement Number ANM–99–01]

Improving Flightcrew Awareness

During Autopilot Operation

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final policy statement.

SUMMARY: This document announces an

FAA general statement of policy

applicable to the type certification of

transport category airplanes. This

document advises the public, in

particular manufacturers of transport

category airplanes and automatic flight

control (autopilot) systems, that the

FAA, when certifying automatic pilot

installations, intends to evaluate various

items that will improve the flightcrew’s

awareness during autopilot operation.

FOR FURTHER INFORMATION CONTACT:

Gregg Bartley, Federal Aviation

Administration, Transport Airplane

Directorate, Transport Standards Staff,

Airplane and Flight Crew Interface

Branch, ANM 111, 1601 Lind Avenue

SW., Renton, WA 98055–4056;

telephone (425) 227–2889; fax (425)

227–1100; e-mail: gregg.bartley@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

Recent incidents and accidents that

have occurred worldwide involving

pilot-autopilot interactions have

emphasized to the FAA the need to

reexamine the current certification

policy relative to autopilot issues.

In 1991, the National Transportation

Safety Board (NTSB) began an

investigation of an incident involving a

transport category airplane that

experienced an in-flight upset. When

the airplane was in cruise at flight level

310, the flightcrew noted that the

inertial navigation system ‘‘FAIL’’ lights

had illuminated. When the flightcrew

cross-checked the instrument panel,

they determined that the airplane was in

a steep right-wing-down banking angle.

The flight lost nearly 10,000 feet of

altitude and the airplane approached

supersonic speeds before the pilots

could complete a recovery. The airplane

eventually made a successful landing,

and there were no injuries.

Investigation of the incident revealed,

among other things, that a failure in the

autopilot system could cause an

airplane to roll slowly into a banking

attitude. The roll rate induced from

such a failure of the autopilot system

may be barely perceptible to the

flightcrew; it also may be difficult to

detect without external visual attitude

references or continuous close

monitoring of the flight attitude

instruments.

The NTSB has advised the FAA of its

concern that some autopilot failures 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.

FAA Evaluation of Flightcrew/Flight

Deck Automation Interfaces

In 1994, the FAA launched a study to

evaluate all flightcrew/flight deck

automation interfaces of current

generation transport category airplanes.

The FAA chartered a Human Factors

Team to conduct the study. Team

members included experts from the

FAA, the European Joint Airworthiness

Authorities (JAA), and academia. The

objective of the study was to look

beyond the label of ‘‘flightcrew error,’’

and examine the contributing factors

from the perspective of design;

flightcrew training and qualifications;

operations; and regulatory processes.

The FAA also tasked the team to

develop recommendations to address

any problems identified.

With regard to autopilot issues, the

Team identified several specific

problematic issues, including:

• Pilot/autopilot interactions that

create hazardous out-of-trim conditions;

• Autopilots that can produce

hazardous speed conditions and may

attempt maneuvers that would not

normally be expected by a pilot; and

• Insufficient wording in the Airplane

Flight Manual regarding the capabilities

and limitations of the autopilot.

Regulatory Initiatives

The FAA has acknowledged the

autopilot issues raised by both the

NTSB and the Human Factors Team,

and has taken steps to address them. For

example, the FAA has tasked the

Aviation Regulation Advisory

Committee (ARAC) to review and

propose harmonized revisions to the

following documents:

• 14 CFR 25.1329 (‘‘Automatic pilot

system’’), which contains FAA’s

standards for certifying automatic pilot

systems on transport category airplanes;

• 14 CFR 25.1335 (‘‘Flight director

systems’’), which contains FAA’s

standards for certifying flight director

systems on transport category airplanes;

and

• Advisory Circular (AC) 25–1329–1A

(‘‘Automatic Pilot Systems Approval,’’

dated July 8, 1968), which describes an

acceptable means by which compliance

with the automatic pilot installation

requirements of § 25.1329 may be

shown.

The work of ARAC currently is in

progress.

Current Certification Standards

In general, the FAA has traditionally

certified automatic pilot systems on

transport category airplanes in

accordance with § 25.1329 on the basis

that:

• The systems are conveniences to

reduce flightcrew workload, and

• The systems do not relieve the

flightcrew of any responsibility for

assuring proper flight path management.

As a result, the autopilot evaluation

criteria contained in AC 25.1329–1A,

are chiefly concerned with the effects of

autopilot failures on the airplane. The

most recent revision to AC 25–7A,

‘‘Flight Test Guide for Certification of

Transport Category Airplanes,’’ also

defines some evaluation criteria for

determining whether the autopilot is

performing its intended function of

relieving the flightcrew of some of their

control functions.

13114 Federal Register / Vol. 66, No. 42 / Friday, March 2, 2001 / Notices

Accordingly, even when the

flightcrew is not manually performing a

specific flight path control function, the

FAA expects the flightcrew to be

‘‘aware’’ when this function is not being

performed safely, and to take

appropriate and timely corrective

action. The installation certification

guidelines presented in AC 25.1329–1A,

for example, state ‘‘* * * at least one

pilot [should] monitor the behavior of

the airplane and associated autopilot

performance at all times.’’

In certifying all autopilot systems to

date, the FAA has accepted the premise

that the capability for this flightcrew

‘‘awareness’’ comes from either:

• Adherence to operational training

and/or procedures;

• A dedicated failure detection and

annunciation feature on the flight deck;

or

• Inherent aircraft operational cues

(for example, a perceived change of

aircraft attitude or change of engine

noise).

As shown by recent relevant accident

and incident cases, one cannot assume

that the flightcrew will reliably detect

and accommodate adverse autopilot

behavior solely from inherent

operational cues; other cues are needed.

Inherent operational cues can be

insufficient because:

1. During normal autopilot operations,

the flightcrew may not be able to detect

operational cues related to significant

changes in aerodynamic characteristics,

such as drag and controllability, as

effectively as during manual operation.

One specific example of this is the

change of control response or ‘‘feel’’

during low speed operations as ice

accumulates on the airplane surfaces,

gradually and imperceptibly reducing

control authority. This condition can

progress, intangible to the flightcrew,

until the autopilot exhausts its control

authority and automatically disengages.

The flightcrew then is suddenly

required to take manual control of the

airplane, which (1) is not in proper trim,

(2) is at a low margin-to-stall, and (3)

has significantly degraded aerodynamic

performance.

2. As pointed out by the NTSB, and

recognized by the FAA, some autopilot

failures 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.

Neither the certification standards nor

the relevant advisory material currently

contain actions or detailed guidance to

address these types of situations.

Because of this, the FAA has found it

necessary and appropriate to provide

additional guidelines for the provision

of design features needed to enable

flightcrew control and awareness of the

unintended changes of speed and

attitude during the operation of the

autopilot system.

Discussion of Proposed Policy

Statement

On, August 30, 1999, the FAA issued

a proposed general statement of policy

(64 FR 49043, September 9, 1999)

concerning how the FAA would

evaluate various items when certifying

automatic pilot installations in transport

category airplanes. (A correction was

later published on September 20, 1999

(64 FR 50872).) This information,

presented in the form of a general

statement of policy, was intended to

clarify, detail, and formally state items

that the FAA:

• Assumes about the flightcrew’s

awareness capability;

• Employs or accepts on an on-going

basis in making compliance findings

relative to autopilot systems; and

• Considers frequently in developing

a means to prevent recurrences of the

accident/incident situations described

previously, or to enable an appropriate

and timely response to other situations

that could result in similar

circumstances.

Comments Received in Response to

Proposed Policy Statement

The FAA received comments on the

proposed policy statement from five

commenters. Many of the comments

submitted were editorial in nature and

did not take issue with the content of

the policy itself. We have incorporated

most of these editorial changes into the

final policy statement where they made

the information clearer or corrected

typographical errors.

The remainder of the comments were

substantive in nature and addressed the

correctness, merit, or appropriateness of

the policy’s technical details. These are

discussed below, divided by the issues

addressed and by comments related to

specific paragraphs of the proposed

policy statement.

‘‘Rulemaking by Policy’’

One commenter states that the

proposed policy statement differs

significantly from existing regulatory

and advisory material, and constitutes

‘‘rulemaking by policy.’’ This

commenter further states that industry

would rather see a statement of the issue

and defer the exact mechanism to

address that issue to the applicant. The

commenter suggests that any new

direction should be harmonized with

the activities of ARAC.

The FAA does not agree with the

commenter. With regard to this policy

statement being ‘‘rulemaking by policy,’’

all features discussed in the policy

statement are covered by the current 14

CFR 25.1309 (especially § 25.1309(c))

and § 25.1329, as well as several other

regulations. This policy statement (and

the planned revisions to the associated

advisory circulars) only defines one

possible implementation that would be

acceptable to the regulatory authorities

when determining compliance with

existing regulations. Neither this policy

statement nor any current or future

advisory circulars define regulations.

The FAA does intend to incorporate

all the material described in the policy

statement in the upcoming revision of

AC 25.1329–1A. Likewise, the European

Joint Aviation Authorities (JAA) also

plan to incorporate this material into

their parallel Advisory Circular Joint

(ACJ) 25.1329.

Change in Role of Flightcrew

One commenter states that current

autopilot systems have been shown, by

operational experience, to be safe. This

commenter asserts that the new policy

would change the role of the flightcrew,

who are currently required to monitor

the performance of an engaged autopilot

at all times. It could make them more

dependent on automatic functions and,

thereby, less likely to be constantly

monitoring the state of the aircraft.

The FAA does not agree with this

commenter. Crew alerting features are

intended to increase pilot awareness,

not replace or reduce the requirement

for crew vigilance and professional

aviation skills. Current crew alerting

features—such as Enhanced Ground

Proximity Warning System, Terrain

Awareness and Warning System, Engine

Fail Indications, or any other alert on

modern transport category aircraft—

enhance safety. The autopilot alert

described in the policy statement is no

different in this respect.

While the autopilot systems currently

in service are safe, there have been

several serious incidents and accidents

of transport category aircraft over the

last 10 years that have involved the

automatic disconnection of an engaged

autopilot when the aircraft was in a mistrimmed configuration or an unusual

attitude. The new features described in

the policy statement are in direct

response those incidents and accidents.

The FAA does not intend for this

policy to alter the roles and

responsibilities of the flightcrew as they

are currently defined. The autopilot

alerts discussed are intended as an

added safeguard to a vigilant flightcrew.

History has shown that pilots sometimes

Federal Register / Vol. 66, No. 42 / Friday, March 2, 2001 / Notices 13115

do miss cues (be they subtle or overt) of

a developing or ongoing unusual

situation. The accidents and incidents

mentioned previously have occurred

when an engaged autopilot

disconnected automatically during a

time when the aircraft was in a

significantly mis-trimmed condition or

an unusual attitude. These accidents

and incidents may have been avoided if

that condition had been brought to the

attention of the flightcrew prior to the

disconnection of the autopilot. The

autopilot alert described in the policy

statement is intended to preclude a

recurrence of accidents and incidents of

that type.

Conflict Between Policy and New

Advisory Material or Rules

Several commenters suggest that the

policy statement should include

language specifying that rules or

advisory material promulgated as a

result of the parallel work of ARAC (and

the Flight Guidance Systems

Harmonization Working Group) would

supersede this or any existing policy

statement if there is a conflict between

the two.

The FAA does not consider the

suggested language necessary. We plan

to ‘‘cancel’’ this policy statement when

the next revision of AC 25.1329–1A is

published. As indicated previously, this

policy statement is interim guidance

until the new revision of AC 25.1329–

1A is issued. Therefore, there is no need

for language in the policy statement that

would give priority to any specific

document.

Comments on Paragraph 2.,

‘‘Definitions’’

One commenter requests the FAA to

clarify the definition of ‘‘hazardous

flight path deviations,’’ which appeared

as paragraph 2.c. in the proposed policy

statement. The commenter states that

the term ‘‘hazardous’’ is used in

multiple ways and this may create

confusion.

The FAA finds it appropriate to delete

this definition from the final policy

statement to avoid confusion.

Additionally, the term is not used

anywhere else in the policy statement,

so its appearance under the heading

‘‘Definitions’’ is not necessary.

Comments on Paragraph 4., ‘‘System

Response’’

Several commenters suggest various

changes to proposed paragraph 4. to

make it clearer and more consistent

with guidance that is already in or

planned for inclusion in FAA and JAA

advisory material. For example, one

commenter suggests that paragraph 4.b.

of the proposal be revised to make clear

that the autopilot should not be allowed

to command unsafe maneuvers,

regardless of the ease of recovery. The

commenter also suggests that the

restrictions on out-of-trim conditions in

the event of a manual autopilot

disconnect, which were listed in

proposed paragraph 4.d., should be

added to paragraph 4.c.’s description of

the automatic disconnect case.

Additionally, the commenter suggests

that examples of maneuvers that might

be considered ‘‘dangerous’’ be included.

Other commenters state that the text

of proposed paragraph 4.d. allows no

‘‘credit’’ for a mis-trim warning and,

thus, would require autopilots to have a

critical trim function, which most

autopilots do not support. Other

commenters suggest use of the term

‘‘ultimate loads’’ instead of ‘‘limit

loads’’ in proposed paragraph 4.d.,

because catastrophic failure conditions

are normally associated with ‘‘ultimate

loads,’’ not ‘‘limit loads.’’ These

commenters also suggest using the term

‘‘unsafe maneuver’’ instead of

‘‘dangerous maneuver’’ (as used in

proposed paragraph 4.f.), because

‘‘dangerous’’ cannot be explicitly

defined.

The FAA has considered these

suggestions and has rewritten paragraph

4 with the following specific changes:

• Paragraph 4.a. is unchanged from

the proposed version.

• Paragraph 4.b. refers to the

autopilot providing guidance or control,

as appropriate, for the intended function

in a safe and predictable manner.

• Paragraph 4.c. describes the

expected system response to the

presence of transient flight control

movements during non-maneuvering

flight and under dynamic conditions.

• Paragraph 4.d. describes the

expected system response, relative to

significant transient flight control

movements, during automatic or manual

disengagement of the autopilot.

• Paragraph 4.e. describes the

expected system response, relative to

significant transients, during other than

normal conditions.

• Proposed paragraph 4.f. has been

deleted as a result of these changes.

(Note that previous references to

‘‘dangerous’’ maneuvers and to ‘‘limit

loads’’ have been deleted from the final

text.)

The wording in the final policy

statement reflects the text that will

appear in the upcoming revision of AC

25.1329–1A.

Comments on Paragraph 5., ‘‘Controls,

Displays, and Alerting’’

Several commenters consider that the

autopilot alert defined in paragraph 5.e.

of the policy statement constitutes a

significant design challenge. First, these

commenters point out that paragraphs

5.e.(1) and 5.e.(2) require ‘‘the autopilot

to remain engaged for some time period

after a failure has been detected by a

monitor (assuming that a monitor exists

to detect all failure conditions).’’ To

these commenters, this appears contrary

to safety in almost all failure conditions.

Many failure conditions require an

immediate automatic disconnection of

the autopilot in order to minimize the

adverse effects of the failure. If autopilot

engagement is maintained for some time

after the failure, the undesirable effects

of the failure will persist and,

consequently, increase the severity of

the failure condition.

Second, these commenters point to

paragraph 5.e.(4), which lists the

conditions for which the flightcrew

alert, and possibly automatic

disengagement of the autopilot, should

be considered. The commenters state

that some of the warning conditions

listed in that paragraph are within the

normal operating flight envelope, and

that it would be difficult to provide

useful alerts without producing frequent

nuisance alarms.

The commenters request clarification

on the intent of paragraph 5.e. and the

conditions that should or should not

result in an automatic disengagement.

The FAA agrees that clarification is

necessary. We recognize that any alert

must be carefully designed so it does

not cause a nuisance alert and, in doing

so, precipitate unnecessary crew

actions. This policy statement calls for

a more advanced (earlier) autopilot alert

to increase the flightcrew’s awareness of

a potentially dangerous condition that

the flightcrew might not otherwise

detect in a timely manner.

Examples of situations that could

warrant advance crew notification are

listed in paragraph 5.e.(4) of the policy

statement. It is not required that the

crew be alerted prior to any automatic

disconnect of an engaged autopilot. All

failure conditions that require an

immediate automatic disconnect, and

whose onset cannot be detected prior to

the actual failure condition, must still

cause an immediate automatic

disconnect. No preceding alert is

required. We have clarified the wording

of the final policy statement in this

regard.

13116 Federal Register / Vol. 66, No. 42 / Friday, March 2, 2001 / Notices

Comments on Paragraph 7., ‘‘Airplane

Flight Manual’’

Several commenters consider the

detailed list of design specifications

contained in paragraph 7 of the

proposed policy statement

inappropriate for inclusion in an

Airplane Flight Manual. One of these

commenters states that it is more

appropriate for this information to be

included in Operations Manuals and

training material. Another commenter

states that the AFM operating

procedures should be limited to only a

general description of the autopilot

capability. The commenters state that

the literal interpretation of what is

asked for in this section would require

reproduction of extensive logical

expressions that are implemented in

either hardware or software. These

commenters question the usefulness of

this information for the flightcrew in

actual flight operations.

The FAA agrees somewhat with the

commenters. We have revised paragraph

7 in the final policy statement to

provide guidance on material that

should be provided in the AFM to

ensure that the appropriate information

related to operation of the flight

guidance system is translated into air

carrier operations. This information is

similar to guidance that will be

provided in the upcoming revision to

AC 25.1329–1A.

Effect of General Statement of Policy

Much of the information presented in

this final policy statement has been

developed from service experience

garnered and flightcrew conventions

practiced throughout the years since the

guidance contained in AC 25.1329–1A

was published in 1968. The FAA has

assembled this information and is

presenting it in this general statement of

policy as a set of ‘‘guidelines’’ that are

appropriate for use with § 25.1329 for

autopilot certification.

Additionally, as discussed previously,

actions currently are underway to revise

the applicable airworthiness standards

(§ 25.1329) and associated advisory

material (AC 25.1329–1A) to more fully

address the autopilot system and other

flight deck issues. Until then, the

guidance provided in this general

statement of policy would serve as a

reference to assist in the certification of

new autopilot systems.

The general policy stated in this

document is not intended to establish a

binding norm; it does not constitute a

new regulation and the FAA would not

apply or rely upon it as a regulation.

The FAA Aircraft Certification Offices

(ACO) that certify transport category

airplanes and/or the automatic pilot

systems installed on them should

generally attempt to follow this policy,

when appropriate. However, in

determining compliance with

certification standards, each ACO has

the discretion not to apply these

guidelines where it determines that they

are inappropriate. The ACO should

coordinate with the Transport Airplane

Directorate, for purposes of

standardization, whenever the ACO

determines that some deviation from

this policy is appropriate. Applicants

should expect that the certificating

officials would consider this

information when making findings of

compliance relevant to new certificate

actions.

Applicants may consider the material

contained in this policy statement as

supplemental to that currently

contained in AC 25.1329–1A when

developing a means of compliance with

the relevant certification standards.

As with all advisory material, this

statement of policy identifies one

means, but not the only means, of

compliance.

For the convenience of the reader, we

have formatted this general statement of

policy in outline form.

The General Statement of Policy

1. General

1.a. Operational experience has

shown that flightcrews may not have

adequate awareness of potentially

hazardous aircraft states or adequate

capability to anticipate sudden,

unexpected actions of the autopilot. In

this regard, the autopilot design should

take into consideration conditions that

could create hazardous deviations in the

flight path, specifically (ref: 14 CFR

25.1329(f), ‘‘Automatic pilot system’’):

• Conditions that could make

continued autopilot operation unsafe; or

• Conditions that could cause the

manual control of an upset following

autopilot disengagement to require

exceptional piloting skill or alertness.

Note that automatic disengagement

may not be the safest autopilot response

for all cases, particularly with trim

conditions that could lead to a

significant upset.

1.b. If automatic functions are

provided that may be used with the

autopilot (e.g., automatic thrust control

or yaw damper), and use of the autopilot

is permitted with any of these functions

inoperative, then the design of the

autopilot should comply with the

provisions of this general policy

statement and Advisory Circular

25.1329–1A, ‘‘Automatic Pilot Systems

Approval’’ with these functions

operative and inoperative.

1.c. The autopilot should perform its

intended function in all configurations

in which it may be used throughout all

appropriate maneuvers and

environmental conditions, including

turbulence and icing, unless an

appropriate operating limitation or

statement is included in the Airplane

Flight Manual.

2. Definitions

2.a. The term autopilot is synonymous

with the term automatic pilot. The term

autopilot includes the sensors,

computers, power supplies, servomotors, servo-actuators, and associated

wiring necessary for its function. It

includes any displays and controls

necessary for the pilot to manage and

supervise the system.

2.b. The term autothrust is

synonymous with the term autothrottle

or automatic throttle control.

2.c. The term extremely improbable is

defined as the average probability per

flight hour of the occurrence of an event

(e.g., a failure condition), which is on

the order of 1 × 10¥9 or less.

Catastrophic failure conditions must be

extremely improbable (ref.

§ 25.1309(b)(1)).

2.d. The term warning is defined as an

indication for a hazard requiring

immediate corrective action by the

flightcrew.

2.e. The term caution is defined as an

indication for an event requiring

immediate crew awareness and possibly

requiring subsequent timely corrective

crew action.

3. Design, Installation, and Maintenance

3.a. The autopilot system design

should not possess characteristics, in

normal operation or when failed, that

would degrade safety or lead to an

unsafe condition, unless such failures

can be limited by design or the effects

can be limited and mitigated by the

pilot response within a reasonable time.

The allowable probability of any failure

should be based on its safety effects in

accordance with the requirements of

§ 25.1309.

3.b. Adequate precautions should be

taken in the design process, and

adequate procedures should be

specified in the maintenance manual, to

prevent the incorrect installation,

connection, or adjustment of parts of the

autopilot if such errors would create a

hazard to the airplane (e.g., torque

clutches or limit switches with a range

of adjustment such that maladjustment

could be hazardous).

3.c. The autopilot should be designed

and installed so that the tolerances

demonstrated during certification tests

can be maintained in service.

Federal Register / Vol. 66, No. 42 / Friday, March 2, 2001 / Notices 13117

4. System Response

4.a. The autopilot should not cause

nuisance oscillations, undue control

activity, or sudden large attitude

changes, especially when configuration

or power changes are taking place. All

maneuvers should be accomplished

smoothly, accurately, and in a manner

similar to normal pilot control.

4.b. The autopilot should provide

guidance or control, as appropriate, for

the intended function of the active

mode(s) in a safe and predictable

manner within the normal flight

envelope.

4.c. In non-maneuvering flight, the

engagement of the autopilot should be

free of perceptible transient flight

control movement. Under dynamic

conditions, including maneuvering

flight, some minimal flight control

transients may be acceptable if they do

not cause significant operational

difficulty for the flightcrew or unsafe

conditions for the occupants.

4.d. Under normal conditions,

automatic or manual disengagement of

the autopilot should be free of

significant transients or out of trim

forces that are not consistent with the

maneuvers being conducted by the

airplane at the time of disengagement. If

multiple autopilots are engaged, any

disengagement of an individual

autopilot should be free of significant

transients and should not adversely

affect the operation of the remaining

autopilot.

4.e. In other than normal conditions,

disengagement of the autopilot may

result in a significant transient. The

flightcrew should be able to respond to

a significant transient without:

• Exceptional piloting skill, alertness,

or strength;

• Forces greater than those given in

§ 25.143 (c); and

• Accelerations or attitudes in the

airplane that might result in a hazard to

secured or non-secured occupants.

5. Controls, Displays, and Alerting

5.a. Unless the probability of failure of

the quick-disconnect button on the

control wheel, or equivalent, is shown

to be extremely improbable, an

alternative means of disengagement,

that is readily accessible in flight,

should be provided.

5.b. The controls, displays, and alerts

should be designed to minimize crew

errors.

5.c. Mode, state, status, and

malfunction indications should be

presented in a manner compatible with

the procedures and assigned tasks of the

flightcrew. The indications should be

grouped in a logical and consistent

manner and be visible from each pilot’s

station under all expected lighting

conditions.

5.d. Autopilot Disconnect Warning:

5.d.(1) Disengagement of the

autopilot, whether intended by the pilot

or not, should trigger both an aural alert

and visual warning during any phase of

flight, since immediate pilot action is

required.

5.d.(2) The aural alert associated with

the autopilot disconnect should be

unique and distinct. The aural alert

should be cancelable by the pilot

pushing the quick-disconnect button on

the control wheel or stick. The aural

alert should sound until cancelled by

the pilot, except that a minimum cycle

should sound. If the autopilot is

disengaged by means of the quickdisconnect button, then an additional

push of this button should be required

to cancel the aural alert.

5.e. An aural alert and a visual

caution should be provided to the

flightcrew for conditions that:

• Could make continued autopilot

operation unsafe, or

• Could cause the manual control of

an upset following autopilot

disengagement to require exceptional

piloting skill or alertness.

5.e.(1) The flightcrew alert should be

generated before the conditions lead to

a situation that could require

exceptional piloting skill or alertness,

such as an automatic disconnect while

the airplane is in an unusual attitude,

significantly out of trim, or near stall

warning.

5.e.(2) Whenever possible, the alert

should provide the flightcrew enough

time to be prepared to place their hands

on the controls and to take appropriate

corrective action (e.g., change thrust, set

trim, disconnect autopilot).

5.e.(3) The thresholds for triggering

the flightcrew alert should be designed

carefully, with consideration for undue

distraction (e.g., nuisance alerts) and

potential ‘‘rippling’’ of multiple alerts

triggered by the same or related

conditions, which could mask or

override the sounding of this alert.

5.e.(4) Conditions that should be

considered for a flightcrew alert and

possibly automatic disengagement

include, but are not limited to:

• Limits of autopilot control

authority;

• Out-of-trim;

• Excessive trim rates;

• Airspeeds greater than those

intended for autopilot operations;

• Low speeds (e.g., less than 1.2 VS1

for the current flap configuration, but

greater than 1.07 VS); and

• Bank and pitch angles beyond those

intended for autopilot operation.

5.e.(5) Detected failure conditions that

require an immediate autopilot

disconnect, such as a fault within the

autopilot processing unit or a failed

autopilot servo, do not require an alert

to be displayed prior to automatic

disconnection. Only those conditions

that are sustained and/or build up over

time such that an advance warning

could be given to the flightcrew prior to

automatic autopilot disengagement (e.g.,

the autopilot close to its maximum

authority in the roll axis for a specific

period of time), or conditions that

would not by themselves cause an

automatic autopilot disengagement, are

candidates for an alert.

5.f. The means provided to comply

with § 25.1329(h) (mode indications

when coupled with airborne navigation

equipment) should also give an

appropriate indication when:

5.f.(1) The autopilot cannot engage the

mode selected by the flightcrew; and

5.f.(2) The system automatically

makes a mode change or mode

disengagement that is considered

operationally significant and, perhaps,

unexpected. (For example, a change

from altitude capture to altitude hold is

significant, but expected; while a

change from vertical path mode to

vertical speed mode is both

operationally significant and

unexpected.)

5.g. If the autopilot has envelope

limiting or protection capability, the

system should provide an alert to

indicate to the pilots when envelope

limiting or protection is invoked and the

condition is sustained and/or flightcrew

action is necessary.

6. Engagement

If a flight director is available and

active, the autopilot should engage in

the same mode as the flight director and

provide consistent flight path guidance.

7. Airplane Flight Manual (AFM)

The following paragraphs provide

guidance on material to be provided in

the Airplane Flight Manual (AFM) to

ensure that the appropriate information

related to flight guidance system (FGS)

operation is translated into air carrier

operations. For additional guidance,

note that FAA Advisory Circular (AC)

25.1581–1 (‘‘Airplane Flight Manual,’’

dated July 14 1997) addresses

requirements of the AFM for transport

category aircraft and distinguishes

between those aircraft that are used in

air carrier operations and those not in

air carrier service. The terminology used

in the AFM should be consistent with

the intended operational use.

Appropriate AFM information related to

13118 Federal Register / Vol. 66, No. 42 / Friday, March 2, 2001 / Notices

low-visibility operations is addressed

in:

• AC 120–28D, ‘‘Criteria for Approval

of Category III Weather Minima for

Takeoff, Landing, and Rollout,’’ and

• AC 120–29A, ‘‘Criteria for

Approving Category 1 and Category II

Landing Minima for FAR 121

Operators.’’

7.a. Limitations. The Limitations

section of the AFM presents those FGS

operating limitations appropriate to the

airplane model as established in the

course of the type certification process,

and as necessary. The FGS operational

limitations (should any exist) should

specify, but not be limited to, the

following:

• Minimum engagement altitude(s) or

height(s), if and when necessary.

Note: If Minimum Engagement Altitude(s)

or height(s) are not specified, then

‘‘maximum displacement deviation’’

information from a pertinent takeoff flight

path and approach profile should be

provided in the AFM Normal Procedures

section, or in the associated Flight Crew

Operation Manual (FCOM).

• Mandatory disengagement

requirements, if necessary.

• Configuration/envelope restrictions,

if and as applicable.

7.b. Abnormal/Emergency Procedures.

Any FGS anomaly that is addressed to

the flight crew by a non-normal

procedure must be included in the

AFM.

7.c. Normal Procedures.

7.c.(1) General. The normal

procedures for use of the FGS should be

documented in the AFM or Flight Crew

Operation Manuals (FCOM), as

appropriate. These procedures should

be demonstrated during the type

certification process. In lieu of

specification of minimum engagement

altitude(s) or height(s), the AFM may

alternately specify ‘‘maximum

displacement deviations’’ from a

specified takeoff flight path, or from a

specified approach profile. This

information may be based on typical

departure or approach flight paths

suited for the aircraft type and for and

failure conditions that are determined

applicable to the type of FGS system

and modes suitable for use.

7.c.(2) Aircraft with Published Flight

Crew Operation Manuals (FCOM).

Airplane Flight Manuals for aircraft for

which the manufacturer has published

FCOM’s should contain essential

information on normal operating

procedures that are considered

‘‘peculiar’’ to the operation of the FGS

for the aircraft type or are otherwise

necessary for safe operation. System

description, specification, and

operational procedures that are

normally associated with flight

guidance systems may be described in

the FCOM.

7.c.(3) Aircraft without Published

FCOM’s. For aircraft that rely on the

AFM as the sole operating manual, the

AFM should contain operating

information sufficient for crew

reference. System description,

operation, checklists, and normal

operating procedures should be

amplified in sufficient detail so that an

appropriately trained flight crew may

operate the FGS under normal

conditions.

Conclusion

As discussed previously, the FAA

intends to update 14 CFR 25.1329 and

associated Advisory Circular (AC)

25.1329–1A to more fully address the

autopilot issues found in this general

statement of policy and others. Until

then, this general statement of policy

serves as a reference to supplement

§ 25.1329, and for use in the

certification of new autopilot systems.

Please inform the appropriate flight

controls and systems designated

engineering representatives (DER) of

this proposed general statement of

policy.

Issued in Renton, Washington, on February

22, 2001.

D.L. Riggin,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 01–5023 Filed 3–1–01; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

Receipt of Noise Compatibility

Program and Request for Review for

Williams Gateway Airport, Mesa, AZ

AGENCY: Federal Aviation

Administration (FAA), Transportation.

ACTION: Notice.

SUMMARY: The FAA announces that it is

reviewing a proposed Noise

Compatibility Program submitted by the

Williams Gateway Airport Authority for

the Williams Gateway Airport, Mesa,

Arizona under the provisions of Title I

of the Aviation Safety and Noise

Abatement Act of 1979 (Pub. L. 96–193)

(hereinafter referred to as ‘‘the Act’’) and

title 14, Code of Federal Regulations

(CFR), part 150. This program was

submitted subsequent to a

determination by the FAA that

associated Noise Exposure Maps

submitted under 14 CFR part 150 were

in compliance with applicable

requirements effective May 2, 2000. The

proposed Noise Compatibility Program

will be approved or disapproved on or

before August 18, 2001.

EFFECTIVE DATE: The effective date of the

start of the FAA’s review of the Noise

Compatibility Program is February 20,

2001. The public comment period ends

April 20, 2001.

FOR FURTHER INFORMATION CONTACT:

Brian Armstrong, Airport Planner,

Airports Division, AWP611.1, Federal

Aviation Administration, WesternPacific Region. Mailing Address: P.O.

Box 92007, Los Angeles, CA, 90009–

2007; Street Address: 15000 Aviation

Boulevard, Hawthorne, CA, 290261;

Telephone Number (310) 725–3614.

Comments on the proposed Noise

Compatibility Program should also be

submitted to the above office.

SUPPLEMENTARY INFORMATION: This

notice announces that the FAA is

reviewing a proposed Noise

Compatibility Program for Williams

Gateway Airport which will be

approved or disapproved on or before

August 18, 2001. This notice also

announces the availability of this

program for public review and

comment.

An airport operator who has

submitted Noise Exposure Maps that are

found by the FAA to be in compliance

with the requirements of 14 CFR part

150, promulgated pursuant to Title I of

the Act, may submit a Noise

Compatibility Program for FAA

approval which sets forth the measures

the operator has taken or proposes for

the reduction of existing noncompatible

uses and for the prevention of the

introduction of additional

noncompatible uses.

The FAA has formally received the

Noise Compatibility Program for

Williams Gateway Airport, effective on

February 20, 2001. It is requested that

the FAA review this material and that

the noise mitigation measures, to be

implemented jointly by the airport and

surrounding communities, be approved

as a Noise Compatibility Program under

Section 104(b) of the Act. Preliminary

review of the submitted material

indicates that it conforms to the

requirements for the submittal of Noise

Compatibility Programs, but that further

review will be necessary prior to

approval or disapproval of the program.

The formal review period, limited by

law to a maximum of 180 days, will be

completed on or before August 18, 2001.

The FAA’s detailed evaluation will be

conducted under the provisions of 14

CFR part 150, Section 150.33. The

primary considerations in the

evaluation process are whether the