[Federal Register Volume 60, Number 189 (Friday, September 29, 1995)]
[Rules and Regulations]
[Pages 50676-50679]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-24170]
[[Page 50675]]
_______________________________________________________________________
Part III
Department of Transportation
_______________________________________________________________________
Federal Aviation Administration
_______________________________________________________________________
14 CFR Part 91
Notification to Air Traffic Control (ATC) of Deviations From ATC
Clearances in Response to Traffic Alert and Collision Avoidance System
Resolution Advisories; Final Rule
Federal Register / Vol. 60, No. 189 / Friday, September 29, 1995 /
Rules and Regulations
[[Page 50676]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 91
[Docket No. 27717; Amdt. No. 91-244]
RIN 2120-AF35
Notification to Air Traffic Control (ATC) of Deviations From ATC
Clearances in Response to Traffic Alert and Collision Avoidance System
Resolution Advisories
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: This action codifies the previously announced policy extended
to pilots during the initial testing of the Traffic Alert and Collision
Avoidance System (TCAS) during the Limited Implementation Plan for
TCAS, and during the actual implementation of TCAS under the TCAS
Transition Plan (TTP). This policy permitted pilots to deviate from an
air traffic control (ATC) clearance, in non-emergency situations, when
responding to a TCAS resolution advisory (RA). The language contained
in current regulations suggests that deviation from an ATC clearance is
authorized only in an emergency situation. The intended effect of this
action is to add the TCAS RA as a reason to deviate from a clearance,
and to require that whenever a pilot deviates from an ATC clearance,
ATC will be advised as soon as possible.
EFFECTIVE DATE: October 30, 1995.
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:
Background
On December 26, 1989, the FAA published a petition for rulemaking,
received from the Air Transport Association of America (ATA), that
requested the FAA amend section 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
section 91.123(a).)
Section 91.123 of the FAR states, in pertinent part, that each
pilot in command who, in an emergency, deviates from an ATC clearance
shall notify ATC of that deviation as soon as possible. The ATA
petition states that TCAS is an advisory system and not an emergency
system. The ATA feels 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 the use of TCAS II. The petition
drew no negative comments and one positive comment from the Airline
Pilots Association (ALPA) that supported the proposal.
On April 9, 1994, the FAA published a Notice of Proposed Rulemaking
(59 FR 22142, Notice No. 94-16) that proposed to amend Section
91.123(a) of the FAR in accordance with the ATA petition. In addition,
this NPRM proposed to amend Sec. 91.123(c) of the FAR to require pilots
to notify ATC as soon as possible if they deviate from a clearance in
response to a RA. The comment period for this NPRM closed on May 31,
1994 and comments are discussed later in this document.
Currently, regulations do not provide for any deviation from an ATC
clearance 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 an ATC
clearance when responding to a TCAS RA. A letter signed by former FAA
Administrator James B. Busey was published as Appendix C to the TTP
Project Management Plan, dated August 1, 1990. The FAA also provided
procedural guidance 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.
Related Agency Actions
On January 10, 1989, the FAA published a final rule (54 FR 940),
known as the ``TCAS rule,'' that required airplanes having more than 30
passenger seats and operated under part 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 part 129
or 135 to be equipped with TCAS I by February 9, 1995; this compliance
date was subsequently extended to December 31, 1995 (59 FR 67584,
December 29, 1994). 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 were required to install TCAS II equipment in accordance with
a phased-in schedule so that 100% of an operator's covered airplanes
would be equipped by December 30, 1993. Operations conducted under part
125 or 129 with airplanes having more than 30 passenger seats were also
required to install TCAS II equipment by December 30, 1993.
TCAS
TCAS is airborne equipment that interrogates 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 transponder without altitude reporting capability
(Mode A), 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 descend) 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, the ``traffic advisory'' (TA), 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 intruding aircraft
relative to the TCAS equipped aircraft. TA's without altitude
information may also be provided from non-altitude reporting
transponder-equipped intruders. TCAS I equipment provides TA's that
only assist the pilot in visually detecting an intruder aircraft. The
second class of advisory, the ``resolution advisory'' (RA), indicates
[[Page 50677]]
the vertical direction and rate that must be achieved by an aircraft in
order to prevent insufficient separation. When an RA occurs, the pilot
flying should respond by direct attention to RA displays and should
maneuver as indicated unless doing so would jeopardize the safe
operation of the flight or unless the flight crew has definitive visual
acquisition of the aircraft causing the RA. TCAS II equipment provides
both traffic and resolution advisories only in the vertical plane.
The Rule
This rule accomplishes two things. First, it authorizes deviations
from an ATC clearance when responding to a TCAS RA. Secondly, it
requires pilots to notify ATC as soon as possible if they deviate from
a clearance in response to a TCAS RA. This action codifies existing
policies and practices that were initiated during the TCAS
implementation period.
Discussion of Comments
Interested persons were invited to participate in this rulemaking
action by submitting written data, views, or arguments. All comments
received during the comment period were considered before making a
determination regarding this final rule. The following is a discussion
of the comments received.
Five comments were received in response to the NPRM. Of this
number, three comments were received from associations and two from
individuals. Most commenters supported amending FAR 91.123(a); however,
three commenters opposed amending FAR 91.123(c).
I. Compliance With ATC Clearances
Most commenters support this amendment which allows flight crews to
deviate from an air traffic control clearance in response to a TCAS RA.
The Air Transport Association of America (ATA) and the Air Line Pilots
Association (ALPA) stated that the proposal is fully consistent with
the ATA petition referenced in the Notice. ATA believes this action
will remove a potential obstacle to the full use of TCAS by allowing
flight crews to follow a TCAS RA without pausing to determine if the RA
maneuver would require the crew to declare an emergency. Another
commenter states that he believes safety would be improved with this
amendment, and supports it. The National Air Traffic Controllers
Association (NATCA) did not comment specifically on this proposed
change, but offers general comments stating they do not believe the air
traffic system is as safe today as it was prior to the introduction of
TCAS.
On December 30, 1987, the President of the United States signed
Public Law 100-223 which, among other provisions, amended the FAA Act
of 1958, Section 601, by adding a new paragraph (f) entitled
``Collision Avoidance Systems.'' This section requires TCAS II on
``each civil aircraft of more than 30 seats and which is used to
provide air transportation of passengers, including intrastate air
transportation of passengers.'' The amendment does not provide for the
exception of any class of civil operation or operator, U.S. or foreign,
from the basic rule. Consequently, the FAA promulgated numerous
regulations (several of which have been referenced earlier in this
document) pertaining to TCAS. In addition, the TTP, along with the
Separation Assurance Task Force (SATF), were established to investigate
and resolve TCAS related problems in the NAS which are discovered
during implementation. Participants in this program include the FAA,
ATA, Regional Airline Association, ALPA, Allied Pilots Association,
NATCA, Transport Canada, TCAS equipment manufacturers and the major,
national and regional air carriers.
The FAA disagrees with NATCA's view that TCAS has compromised
safety. Since the introduction of TCAS into the NAS, both air traffic
controllers and flight crews have adjusted their operating procedures.
With the assistance and cooperation of flight crews and air traffic
controllers, surveys have been collected and volumes of data analyzed.
As issues surface, the TTP provides guidance for timely resolution that
has resulted in better training for both pilots and controllers, the
issuance of two advisory circulars addressing the use of TCAS,
amendments to the controllers handbook and the Airman's Information
Manual (AIM), and updating the TCAS software in order to eliminate
false and nuisance RA's.
At the second annual International TCAS Conference held in Reston,
Virginia in September, 1993, TCAS was lauded by many flight crews as a
safety enhancing cockpit device.
For example, TCAS was credited by the captain of a major air
carrier for saving the lives of nearly 700 people in two B747 aircraft
traveling over the Pacific Ocean.
The TCAS Industry Alert Bulletin #5, issued February 18, 1994,
states that during the prior two years, 16 encounters had occurred
wherein TCAS II displayed unnecessary resolution advisories that
directed pilots to cross through each other's altitudes. The RA's were
unnecessary because the aircraft were safely separated by the ATC
system. In each of these encounters, the TCAS logic detected the high
vertical closure rate of the two aircraft and predicted the close
proximity of the aircraft without knowing that the aircraft intended to
level off 1000 feet apart in altitude.
In order to eliminate these unnecessary RA's, a new version of the
TCAS logic (Version 6.04A) was created and installation required by 12/
31/94. This logic will not generate altitude-crossing RAs when aircraft
level off within 1000 feet vertically of one another. None of the 16
encounters previously mentioned would have resulted in altitude-
crossing RAs with the Version 6.04A logic installed.
II. ATC Notification
ATA and ALPA oppose this proposal which requires flight crews to
inform ATC as soon as possible when deviating from an ATC clearance in
response to a TCAS RA. ALPA states they do not oppose notifying ATC of
any deviation caused by responding to a TCAS RA; however, they believe
the proposal may imply a sense of urgency for pilots to advise ATC of a
deviation at a time when complete attention must be focused on
identifying the intruder and responding to the RA. ALPA states this
sense of urgency may also be prompted by a concern over possible
enforcement action should the crew neglect to report the event due to a
directed frequency change or some other unanticipated event. ATA
comments that the phrase ``as soon as possible'' implies that
notification to ATC of a deviation should take place prior to executing
the maneuver. ATA suggests the word ``practical'' be used in lieu of
``possible'' which would be consistent with the AIM.
The FAA does not agree with replacing the word ``possible'' with
``practical''. The word ``possible'' does not mean that the
notification has to take place before the pilot has executed the
appropriate maneuver. ``Possible'' does, however, contain a greater
urgency than the word ``practical,'' and would require notification to
ATC of the deviation as soon as the pilot maneuvers the aircraft to a
safe operating environment. The language is consistent with current
wording contained in the regulation that requires a flight crew who, in
an emergency, deviates from an ATC clearance to notify ATC as soon as
possible. If a pilot deviates from an ATC clearance, the controller
must be given timely notification of that deviation so that appropriate
instructions and/or
[[Page 50678]]
advisories can be issued to ensure a safe, orderly, and expeditious
flow of traffic. By advising ATC as soon as possible that an RA has
been received, the controller can evaluate the situation, determine the
most appropriate and safe course of action, and issue alternate
instructions if necessary.
ALPA states that the requirement to report a deviation from an ATC
clearance as a result of an RA is stated in the Airman's Information
Manual (AIM), FAA Advisory Circular 120-55, and each TCAS equipped
aircraft flight operations manual. Consequently, the commenter believes
this proposal is redundant and unnecessary.
The FAA acknowledges there are several FAA publications which
explain and encourage pilots to communicate with ATC when deviating
from a clearance upon receipt of a RA. However, the FAA has determined
that safety within the NAS can only be maintained if pilots are
required to advise controllers when a deviation from an ATC clearance
has occurred as a result of an RA.
NATCA opposes this rule change due to concerns for the safety of
persons operating in the NAS. However, NATCA does not provide specific
instances of how or where safety is compromised, but merely reiterates
their ongoing concern with the TCAS program.
The FAA has determined that pilot notification of a deviation from
a clearance due to a TCAS RA enhances safety in the NAS. 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. If a pilot deviates from an ATC
clearance, the controller must 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 that an RA has been received, the
controller can evaluate the situation, determine the most appropriate
and safe course of action, and issue alternate instructions if
necessary.
III. Resolution Advisory Maneuver--An Emergency?
One commenter contends that any deviation from an ATC clearance is
an emergency; therefore, this rule change is not needed. The commenter
believes the cause of the deviation need not be an emergency, but the
mere fact that an aircraft is not following an ATC clearance should be
considered an emergency. The commenter suggested the phrase ``in an
emergency'' be deleted from the rule; thereby, any time an aircraft
deviates from an ATC clearance, regardless of the reason, ATC will be
notified.
The FAA disagrees that an RA maneuver is an emergency action. TCAS
is designed to serve as a backup (safety net) to visual collision
avoidance, application of ``right of way rules'', and air traffic
separation services. Since its inception, TCAS has been considered by
the FAA and industry to be a supplement to the ATC system that provides
flight guidance to ensure adequate separation from other aircraft.
Additionally, although the suggestion to remove the word ``emergency''
from the language of the regulations is outside the scope of this
rulemaking, the FAA will consider the merits of the comment for
possible future rulemaking.
Regulatory Evaluation Summary
Executive Order 12866 established the requirement that, within the
extent permitted by law, a Federal regulatory action may be undertaken
only if the potential benefits to society for the regulation outweigh
the potential costs to society. In response to this requirement, and in
accordance with Department of Transportation policies and procedures,
the FAA has estimated the anticipated benefits and costs of this
rulemaking action. The results are stated in this section. The FAA has
determined that this rule change is not a ``significant rulemaking
action,'' as defined by Executive Order 12866 (Regulatory Planning and
Review).
The FAA has determined that this rule will be cost-beneficial
because it imposes no costs and would promote air safety. There will
not be any changes in notification or reporting requirements for
deviations from ATC clearances that are necessary to avoid potential
collision hazards. This action codifies a previously announced policy
that pilots who deviate from their assigned altitudes in response to a
TCAS RA will provide timely notice, as soon as possible, to air traffic
control. Such non-written, voice notification will 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 action will 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 rule will 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 action will not have a significant economic
impact, positive or negative, on a substantial number of small
entities. This assessment is based on the fact action will not impose
any additional cost on aircraft operators.
Paperwork Reduction Act
There are no requirements for information collection associated
with this action 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
This regulation will 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 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 action 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
regulation is not a ``significant regulatory action'' under Executive
Order 12866. This 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 regulation 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.
List of Subjects in 14 CFR Part 91
Air traffic control, Aircraft, Aviation safety.
[[Page 50679]]
The Amendment
In consideration of the foregoing, the Federal Aviation
Administration amends part 91 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: 42 U.S.C. 4321 et seq.; 49 U.S.C. app. 1301, 1303,
1344, 1348, 1352 through 1355, 1401, 1421 through 1431, 1471, 1472,
1502, 1510, 1522, and 2121 through 2125, 2157, 2158; 49 U.S.C.
106(g); articles 12, 29, 31, and 32(a) of the Convention on
International Civil Aviation (61 Stat. 1180); E.O. 11514, 35 FR
4247, 3 CFR, 1966-1970 Comp., p. 902.
2. Section 91.123 is amended by revising paragraphs (a) and (c) to
read 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 VFR 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 resolution advisory,
deviates from an ATC clearance or instruction shall notify ATC of that
deviation as soon as possible.
* * * * *
Issued in Washington, D.C. on September 13, 1995.
David R. Hinson,
Administrator.
[FR Doc. 95-24170 Filed 9-28-95; 8:45 am]
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