[Federal Register Volume 59, Number 82 (Friday, April 29, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-10167]
[[Page Unknown]]
[Federal Register: April 29, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 91
[Docket No. 27717; Notice No. 94-16]
RIN 2120-AF35
Notification to ATC of Deviations From ATC Clearances and
Instructions in Response to Traffic Alert and Collision Avoidance
System Resolution Advisories
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This action proposes to codify a previously announced policy
extended to pilots during the initial testing of TCAS, during the
Limited Implementation Plan (LIP) for TCAS, and during the actual
implementation of TCAS under the TCAS Transition Plan (TTP) that
permitted pilots to deviate from an air traffic control (ATC) clearance
or instruction in non-emergency situations in response to a traffic
alert and collision avoidance system (TCAS) resolution advisory (RA).
The language contained in current regulations suggests that deviation
from an ATC clearance is only authorized in an emergency situation.
This proposal would add the TCAS RA as a reason to deviate from a
clearance. This proposal would require that whenever a pilot deviates
from an ATC clearance or instruction, ATC would be advised as soon as
practicable. This proposal is intended to clarify and define pilot
reporting requirements in the event a pilot deviates from an air
traffic control clearance or instruction in response to a TCAS
resolution advisory.
DATES: Comments must be received on or before May 31, 1994.
ADDRESSES: Comments on this notice should be mailed, in triplicate, to:
Federal Aviation Administration, Office of Chief Counsel, Attention:
Rules Docket (AGC-200), Docket No. 27717, 800 Independence Avenue, SW.,
Washington, DC 20591. Comments delivered must be marked Docket No.
27717. Comments may be examined in room 915G weekdays between 8:30 a.m.
and 5 p.m., except on Federal holidays.
FOR FURTHER INFORMATION CONTACT:
Mrs. Ellen Crum, Air Traffic Rules Branch, ATP-230, Airspace Rules and
Aeronautical Information Division, Federal Aviation Administration, 800
Independence Avenue, SW., Washington, DC 20591; telephone (202) 267-
8783.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Comments relating to the environmental, energy,
federalism, or economic impact that might result from adopting the
proposals in this notice are also invited. Substantive comments should
be accompanied by cost estimates. Comments should identify the
regulatory docket or notice number and should be submitted in
triplicate to the Rules Docket address specified above. All comments
received on or before the closing date for comments specified will be
considered by the Administrator before taking action on this proposed
rulemaking. The proposals contained in this notice may be changed in
light of comments received. All comments received will be available,
both before and after the closing date for comments, in the Rules
Docket for examination by interested persons. A report summarizing each
substantive public contact with Federal Aviation Administration (FAA)
personnel concerned with this rulemaking will be filed in the docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must include a pre-addressed,
stamped postcard on which the following statement is made: ``Comment to
Docket No. 27717.'' The postcard will be date stamped and mailed to the
commenter.
Availability of NPRM's
Any person may obtain a copy of this NPRM by submitting a request
to the Federal Aviation Administration, Office of Public Affairs,
Attention: Public Inquiry Center, APA-430, 800 Independence Avenue,
SW., Washington, DC 20591, or by calling (202) 267-3484. Communications
must identify the notice number of this NPRM.
Persons interested in being placed on the mailing list for future
NPRM's should request from the above office a copy of Advisory Circular
No. 11-2A, Notice of Proposed Rulemaking Distribution System, which
describes the application procedure.
Background
On December 26, 1989, the FAA published a petition for rulemaking
received from the Air Transport Association (ATA) that requested the
FAA to amend Sec. 91.75(a) of the Federal Aviation Regulations (FAR) to
permit a pilot to deviate from an ATC clearance when responding to a
TCAS RA (54 FR 52951). [Effective August 18, 1990, Part 91 of the FAR
was revised (54 FR 34284; August 18, 1989) to renumber all of its
sections. Section 91.75(a) was renumbered as Sec. 91.123(a).]
Currently, the FAR's do not provide for any deviation from an ATC
clearance or instruction except in an emergency situation. However,
during the initial trial and implementation of TCAS II, the FAA
notified pilots that no enforcement action would be initiated if the
pilot deviated from ATC clearances when responding to TCAS RA's. This
notification was provided in a letter signed by the former FAA
administrator James B. Busey. The letter was published as appendix C to
the TCAS Transition Program (TTP) Project Management Plan, dated August
1, 1990. The FAA also provided procedural guidance, including ATC
communication requirements, in Advisory Circular 120-55, ``Air Carrier
Operational Approval and Use of TCAS II'' dated October 23, 1991, and
later amended as AC 120-55A dated August 27, 1993. The policy and
guidance proved successful during the testing and implementation of
TCAS II.
The ATA petition states that TCAS is an advisory system and not an
emergency system. The ATA felt that pilots should be able to comply
with a TCAS RA without exercising emergency authority. The ATA petition
mirrors current FAA policy and guidance for use of TCAS II. The
petition drew no negative comments and one positive comment, from the
Airline Pilots Association (ALPA), in support of the proposal.
Section 91.123 of the FAR states, in pertinent part, that each
pilot in command who, in an emergency, deviates from an ATC clearance
or instruction shall notify ATC of that deviation as soon as possible.
This provision could be interpreted to mean that deviations for non-
emergency related reasons are not authorized.
TCAS II is now installed on approximately 6000 aircraft worldwide.
Over the past 3 years, more than 15 million flight hours of operational
experience have been accumulated.
TCAS Overview
TCAS equipment in an airplane interrogates the ATC transponders of
other aircraft nearby. By computer analysis of the replies, TCAS
equipment determines which transponder-equipped aircraft are potential
collision hazards and provides appropriate advisory information to the
flight crew. If a TCAS-equipped airplane interrogates an aircraft that
is equipped with a Mode A transponder, range and azimuth information
will be provided to the TCAS-equipped aircraft. If the interrogated
aircraft is equipped with an altitude encoding transponder (Mode C or
Mode S), then relative altitude information will be provided in
addition to range and azimuth. TCAS equipment cannot detect the
presence of an aircraft that is not equipped with a transponder.
TCAS equipment performs proximity tests on each detected target. If
the path of a target is projected to pass within certain horizontal and
vertical distance criteria, then that target is declared an intruder.
An intruder that is determined to pose an even greater risk of
collision is declared a threat. When a threat is declared, TCAS
equipment will determine the appropriate direction that the TCAS-
equipped aircraft must move (climb or descent) and the vertical rate
that must be maintained to achieve separation from the threat.
There are two classes of advisories provided by TCAS equipment. The
first class, traffic advisories (TA's), provides supplemental
information to the pilot that aids in visual detection of other
aircraft. TA's include the range, bearing, and, if the intruder has
altitude-reporting equipment, the altitude of the intruding aircraft
relative to the TCAS-equipped aircraft. TA's without altitude may also
be provided from non-altitude reporting transponder-equipped intruders.
The second class of advisories, resolution advisories (RA's), indicates
the vertical direction and rate that must be achieved to prevent
insufficient separation.
TCAS I equipment provides TA's that only assist the pilot in
visually detecting an intruder aircraft. TCAS II equipment provides
TA's and RA's only in the vertical plane. TCAS III, which is still
under development, will provide TA's and RA's in both the vertical and
horizontal planes.
Related Agency Actions
On January 10, 1989, the FAA published a final rule (54 FR 940),
the ``TCAS rule,'' which required airplanes having more than 30
passenger seats and operated under parts 121, 125, or 129 to be
equipped with TCAS II by December 30, 1991. The TCAS rule also required
airplanes having 10 to 30 passenger seats and operated under parts 129
or 135 to be equipped with TCAS I by February 9, 1995.
On April 9, 1990, the FAA amended the TCAS rule by revising the
schedule for the installation of TCAS II equipment in airplanes having
more than 30 passenger seats (55 FR 13242). Operators of airplanes
having more than 30 passenger seats and operated under part 121 are
required to install TCAS II equipment in accordance with a phased-in
schedule so that 100% of an operator's covered airplanes will have TCAS
II equipment by December 30, 1993. Operations conducted under parts 125
or 129 with airplanes having more than 30 passenger seats are also
required to install TCAS II equipment by December 30, 1993.
The Proposal
The FAA believes that most TCAS RA's will involve changes in the
rate of descent or climb in order to mitigate potential collision
hazards. Such TCAS RA's routinely will not necessitate a pilot
deviating from an ATC clearance or instruction. The issue of advising
ATC of the receipt of or compliance with a TCAS RA that does not
involve a deviation from a clearance or instruction is a matter of
pilot judgment and discretion.
The FAA also has determined that the majority of deviations from
ATC clearances or instructions in response to TCAS RA's will be
appropriate and necessary to resolve potential collision hazards with
other transponder-equipped aircraft. In such cases, pilots executing
the appropriate maneuvers are expected to advise ATC of the deviations
as soon as possible.
The current language of Sec. 91.123(c) provides that a pilot who
deviates from an ATC clearance or instruction, in an emergency, shall
notify ATC as soon as possible. If a pilot deviates from an assigned
altitude in response to a TCAS RA, but does not believe that an
emergency exists, that pilot may determine, based on current
Sec. 91.123(c), that an advisory to ATC is not required. The proposal
would specifically state that a report to ATC is required.
Air traffic controllers base their control and traffic management
decisions on the expectation that pilots will comply with ATC-assigned
routes, altitudes, and other clearances and instructions. If a pilot
must deviate from an ATC clearance or instruction, the controller mut
be given timely notification of that deviation so that appropriate
instructions and/or advisories can be issued to ensure a safe, orderly,
and expeditious flow of traffic. By advising ATC as soon as possible
after a deviation, the controller can evaluate the situation, determine
the most appropriate and safe course of action, and issue alternate
instructions if necessary.
The FAA has concluded that this proposed rule is necessary to
codify existing policy for pilots to notify ATC as soon as possible
after any deviation from an ATC clearance or instruction in response to
a TCAS RA, whether that deviation was emergency-related or not.
Further, the FAA has determined that this proposed rule will not add or
change any notification or reporting requirements for deviations that
are necessary to resolve potential or imminent collision hazards. The
FAA has always intended that notification to ATC of a deviation from a
clearance or instruction is necessary and required, whether that
deviation is emergency-related or not. This action serves only to
reinforce and codify that intention.
Accordingly, the FAA proposes to amend Sec. 91.123 of the FAR to
authorize deviations from an ATC clearance or instruction when
responding to a TCAS RA. In addition, pilots would be required to
advise ATC of the TCAS RA deviation from an ATC clearance or
instruction whether emergency-related or not.
Economic Evaluation
The FAA has determined that this NPRM is not a ``significant
regulatory action'', as defined by Executive Order 12866 (Regulatory
Planning and Review). The anticipated benefits and costs associated
with this NPRM are summarized below. (A detailed discussion of costs
and benefits is contained in the full evaluation in the docket for this
NPRM). The agency has determined that this proposed rule would be cost-
beneficial because it imposes no costs and would promote air safety.
There would not be any changes in notification or reporting
requirements for deviations from ATC clearances that are necessary to
avoid potential collision hazards. The proposal would clarify and
codify existing policy and guidance requirements that pilots who
deviate from their assigned altitudes in response to a TCAS resolution
advisory provide timely notice of that deviation to air traffic control
in both non-emergency situations and emergency situations. Such
notification would give controllers an opportunity to resolve any
conflicts resulting from a TCAS II- equipped aircraft being at other
than the assigned altitude.
International Trade Impact Statement
This proposed rule would not impose a competitive disadvantage to
either U.S. air carriers doing business abroad or foreign air carriers
doing business in the United States. This assessment is based on the
fact that this proposed rule would not impose additional costs on
either U.S. or foreign air carriers.
Regulatory Flexibility Determination
In accordance with the Regulatory Flexibility Act of 1980, the FAA
has determined that this proposed rule would not have a significant
economic impact, positive or negative, on a substantial number of small
entities. This assessment is based on the fact that the proposed rule
would not impose any additional cost on aircraft operators.
Paperwork Reduction Act
There are no requirements for information collection associated
with this proposed rule that would require approval from the Office of
Management and Budget pursuant to the Paperwork Reduction Act of 1980
(Pub. L. 96-511).
Federalism Implications
The regulation proposed herein would not have substantial direct
effects 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, in
accordance with Executive Order 12612, it is determined that this
proposed rule does not have sufficient federalism implications to
warrant the preparation of a Federalism Assessment.
International Civil Aviation Organization and Joint Aviation
Regulations
In keeping with the U.S. obligations under the Convention on
International Civil Aviation (ICAO), it is FAA policy to comply with
ICAO Standards and Recommended Practices (SARP) to the maximum extent
practicable. The FAA has determined that this NPRM complies with the
ICAO SARP.
Conclusion
For the reasons discussed in the preamble, and based on the
findings in the Regulatory Flexibility Determination and the
International Trade Impact Analysis, the FAA has determined that this
proposed regulation is not a ``significant regulatory action'' under
Executive Order 12866. This proposed regulation is not considered
significant under DOT Order 2100.5, Policies and Procedures (44 FR
11034; February 26, 1979). In addition, the FAA certifies that this
proposed regulation, if adopted, will not have a significant economic
impact, positive or negative, on a substantial number of small entities
under the criteria of the Regulatory Flexibility Act. A regulatory
evaluation of the NPRM, including a Regulatory Flexibility
Determination and Trade Impact Analysis, has been placed in the docket.
A copy may be obtained by contacting the person identified under FOR
FURTHER INFORMATION CONTACT.
List of Subjects in 14 CFR Part 91
Air traffic control, Aircraft, Aviation safety.
The Proposed Amendment
In consideration of the foregoing, the Federal Aviation
Administration proposes to amend Sec. 91.123 of the Federal Aviation
Regulations (14 CFR part 91) as follows:
PART 91--GENERAL OPERATING AND FLIGHT RULES
1. The authority citation for part 91 continues to read as follows:
Authority: 49 U.S.C. 1301(7), 1303, 1344, 1348, 1352 through
1355, 1401, 1421 through 1431, 1471, 1472, 1502, 1510, 1522, and
2121 through 2125; articles 12, 29, 31, and 32(a) of the Convention
on International Civil Aviation (61 Stat. 1180); 42 U.S.C. 4321 et
seq.; E.O. 11514, 35 FR 4247, 3 CFR, 1966-1970 Comp., p. 902; 49
U.S.C. 106(g).
2. Section 91.123 is amended by revising paragraphs (a) and (c) as
follows:
Sec. 91.123 Compliance with ATC clearances and instructions.
(a) When an ATC clearance has been obtained, no pilot in command
may deviate from that clearance unless an amended clearance is
obtained, an emergency exists, or the deviation is in response to a
traffic alert and collision avoidance system resolution advisory.
However, except in Class A airspace, a pilot may cancel an IFR flight
plan if the operation is being conducted in VRR weather conditions.
When a pilot is uncertain of an ATC clearance, that pilot shall
immediately request clarification from ATC.
* * * * *
(c) Each pilot in command who, in an emergency, or in response to a
traffic alert and collision avoidance system (TCAS) resolution
advisory, deviates from an ATC clearance of instruction shall notify
ATC of that deviation as soon as possible.
* * * * *
Issued in Washington, DC on April 21, 1994.
Harold W. Becker,
Manager, Airspace Rules and Aero Information Division, Air Traffic
Rules & Procedures Service.
[FR Doc. 94-10167 Filed 4-28-94; 8:45 am]
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