[Federal Register Volume 84, Number 128 (Wednesday, July 3, 2019)]
[Rules and Regulations]
[Pages 31713-31717]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-14127]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 91
[Docket No. FAA-2019-0539]
Statement of Policy on Performance Requirements for Operators of
Aircraft That are Equipped With Automatic Dependent Surveillance-
Broadcast (ADS-B) Out
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Policy statement.
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SUMMARY: This action announces the FAA's policy on performance
requirements for certain operations of aircraft with Automatic
Dependent Surveillance-Broadcast (ADS-B) Out equipment in ADS-B
airspace after January 1, 2020. Under the circumstances identified in
this policy, the FAA is providing assurance to operators that it will
not consider degradation in Global Positioning System performance due
to conditions outside the operator's control that results in an
operation falling below ADS-B rule requirements to constitute non-
compliance, provided the operator
[[Page 31714]]
has exercised appropriate due diligence prior to conducting an
operation.
DATES: The policy described herein is effective January 2, 2020.
FOR FURTHER INFORMATION CONTACT: For technical information concerning
this action, contact David Gray, Surveillance and Broadcast Group
Manager, Air Traffic Organization, at (202) 267-3615.
SUPPLEMENTARY INFORMATION:
Authority for This Action
The FAA's authority to issue rules on aviation safety is found in
Title 49 of the United States Code (49 U.S.C.). Subtitle I, Section
(Sec. ) 106, describes the authority of the FAA Administrator.
Subtitle VII, Aviation Programs, describes in more detail the scope of
the agency's authority.
The ADS-B Out equipage and performance requirements were
promulgated under the authority described in Subtitle VII, Part A,
Subpart I, Section 40103, Sovereignty and use of airspace, and Subpart
III, Section 44701, General requirements. Under section 40103, the FAA
is charged with prescribing regulations on the flight of aircraft
(including regulations on safe altitudes) for navigating, protecting,
and identifying aircraft, and the efficient use of the navigable
airspace. Under section 44701, the FAA is charged with promoting safe
flight of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce.
Under Sec. 91.227 of Title 14 of the Code of Federal Regulations
(14 CFR), which was issued in accordance with the FAA's statutory
authority in sections 40103 and 44701, the FAA set forth the ADS-B Out
equipment performance requirements, including accuracy and integrity
performance standards. This policy statement informs operators about
how the FAA will handle: (1) Operators when their avionics produce
broadcast elements with values less than required by Sec. 91.227 due
to circumstances beyond the operator's control; and (2) circumstances
in which the operator cannot use the Service Availability Prediction
Tool (SAPT) due to a system outage.
I. Background
In 2010, the FAA issued a final rule prescribing equipage
requirements and performance standards for ADS-B Out avionics on
aircraft operating in certain airspace after January 1, 2020.\1\ ADS-B
Out is an advanced surveillance technology that combines an aircraft's
positioning source, other aircraft avionics, and a receiver
infrastructure to create an accurate and shared surveillance picture
between aircraft and air traffic control (ATC). ADS-B Out provides air
traffic controllers with real-time position information that is, in
most cases, more accurate than the information available with current
radar-based systems. With more accurate information, ATC will be able
to position and separate aircraft with improved precision and timing so
that efficiency and capacity will increase beyond current levels to
meet the predicted demand for ATC services while maintaining or
improving safety.
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\1\ Final Rule, Automatic Dependent Surveillance-Broadcast (ADS-
B) Out Performance Requirements to Support Air Traffic Control
(ATC), 75 FR 30160 (May 28, 2010).
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ADS-B Position Sources
Aircraft with ADS-B Out equipment continually broadcast
information, such as identification, current position, altitude, and
velocity, through an onboard transmitter, which can be received by ADS-
B ground stations (or other capable receivers) and by other aircraft
appropriately equipped to receive this information. The ADS-B Out rule
specifies the aircraft's ADS-B Out equipment performance requirements
for each flight in rule airspace rather than requiring any particular
type of position source. All currently approved position sources rely
on a Global Positioning System (GPS) receiver.\2\ The quality of each
type of receiver can be described by its ``rule performance''
availability, which means the GPS receiver's ability to achieve the
performance requirements of Sec. 91.227(c)(1)(i) and (iii) for
Navigation Accuracy Category for Position (NACp) and Navigation
Integrity Category (NIC). Technical Standard Order (TSO)-C166b and TSO-
C154c contain the avionics standards for outputting NACp and NIC. To
date, Wide Area Augmentation System (WAAS) is the only GPS position
source that consistently provides the equivalent availability to
radar.\3\ Operators who equip with GPS position sources such as
Selective Ability \4\-On (SA-On) or SA-Aware are more likely to
experience performance outages that limit their access to the airspace
defined in the rule.\5\
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\2\ GPS is a specific type of Global Navigation Satellite System
(GNSS).
\3\ FAA has determined that certain GPS tightly integrated with
inertial navigation systems will also provide 99.9 percent
availability.
\4\ SA was a feature that deliberately degraded the GPS
satellite signal, resulting in a reduction of the reported accuracy
of an aircraft's position. On May 1, 2000, the United States
deactivated SA to allow more accurate civilian use of GPS. SA is not
included in new GPS satellite designs.
\5\ For additional information about SA-On and SA-Aware, please
refer to Exemption No. 12555 at https://www.regulations.gov/searchResults?rpp=25&po=0&s=FAA-2015-0971&fp=true&ns=true.
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FAA ADS-B Service Availability Prediction Tool (SAPT)
The ADS-B SAPT is a preflight availability prediction tool,
developed by the FAA, that predicts the ability of an aircraft to meet
the requirements of Sec. 91.227(c)(1)(i) and (iii) along a given route
of flight. This prediction is based on the ability of the aircraft's
position source (GPS receiver) to meet performance requirements
specified in FAA TSOs C129, C129a, C145c/C146c, and C196, as well as
the predicted status of the GPS constellation. The SAPT will also
evaluate if backup surveillance is available where ADS-B outages are
predicted.\6\ The ADS-B SAPT is primarily intended for pilots,
dispatchers, and commercial operators to verify their predicted
surveillance availability before flight and ensure compliance with the
ADS-B Out rule.\7\
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\6\ FAA plans to begin divesture of some radar infrastructure as
part of the transition to a satellite-based navigation and
surveillance system. During the period from 2020 to 2025, FAA's
planned radar divestures will focus primarily on eliminating
redundant/overlapping radars.
\7\ For more information on the SAPT, the FAA has developed the
ADS-B SAPT/Receiver Autonomous Integrity Monitoring (RAIM) User
Guide, which is available at https://sapt.faa.gov/adsb-start.php.
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Exemption No. 12555
In April 2015, Airlines for America (A4A) petitioned the FAA, on
behalf of A4A member airlines, for an exemption from the Navigation
Accuracy Category for Position (NACp) and Navigation Integrity Category
(NIC) requirements of the rule. In August 2015, the Administrator
issued Exemption No. 12555, a time-limited grant of exemption from
Sec. 91.227(c)(1)(i) and (iii) for the period from January 1, 2020
through December 31, 2024. Exemption No. 12555 permits operations in
ADS-B Out rule airspace during periods when the GPS position provided
to the installed ADS-B Out equipment does not achieve the required
accuracy or integrity performance, provided certain conditions and
limitations are met.
For those aircraft meeting the performance requirements of TSO-C196
(SA-Aware), the operator is not required to perform a preflight
availability prediction prior to conducting an operation under the
exemption.\8\ For
[[Page 31715]]
operators having aircraft equipped with TSO-C129 (SA-On) approved GPS
receivers that do not meet the performance requirements of TSO-196 or
TSO-C145/146, the operator must run a preflight prediction.\9\ Although
the exemption does not require operators with SA-On to use the SAPT for
preflight availability prediction, if the operator uses its own
preflight availability prediction tool and receives an indication that
performance will fall below rule requirements, it must use SAPT to
determine whether backup surveillance is available along the planned
route of flight per Exemption No. 12555.
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\8\ To accommodate these aircraft in the system under the
requested exemption, the FAA effectively accepted the risk of
degraded performance from SA-aware GPS receivers (if the GPS
constellation is degraded). The FAA noted, however, that it could
not accept this risk indefinitely and limited the relief in the
exemption to 5 years.
\9\ For SA-on GPS receivers using the current GPS constellation,
the rule performance availability is approximately 95 percent or
higher.
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SA-On and SA-Aware Without Exemption No. 12555 Relief
Some operators of aircraft with SA-On and SA-Aware receivers did
not petition the FAA for relief under Exemption No. 12555. As such,
they are not exempt from meeting the performance requirements in Sec.
91.227(c)(1)(i) and (iii). Under Sec. 91.103, a pilot in command is
required before beginning a flight to become familiar with all
available information concerning that flight, which includes, among
other things, conducting due diligence to confirm that a planned route
of flight will comply with the ADS-B performance requirements in Sec.
91.227(c)(1)(i) and (iii).\10\ Given the previously identified
limitations of SA-On and SA-Aware receivers, the use of a preflight
prediction tool is a reliable way of satisfying due diligence
requirements under Sec. 91.103. Operators may use any reliable
preflight prediction tool; however, the SAPT currently provides a
comprehensive and reliable preflight prediction for operators.
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\10\ Under part 121, the aircraft dispatcher (or director of
operations for supplemental operations) shares operational control
with the pilot in command and is jointly responsible for preflight
planning. Generally, the aircraft dispatcher will perform the
preflight prediction to satisfy preflight planning requirements.
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II. Discussion of FAA's Policy
After January 1, 2020, unless otherwise authorized by ATC, all
aircraft operating in the airspace identified in Sec. 91.225 must
comply with the ADS-B Out equipage and performance requirements in
Sec. Sec. 91.225 and 91.227. Nothing in this notice shall be deemed to
modify or alter those requirements established in the 2010 final rule.
In this notice, the FAA explains circumstances outside of an
operator's control that may result in a temporary degradation of GPS
performance and an apparent violation of Sec. 91.227. The purpose of
this notice is to announce FAA's policy for certain operations of
aircraft with ADS-B Out that may encounter such circumstances,
including: (1) Operations that are required to use SAPT under the
conditions of Exemption No. 12555 or non-exemption holders required to
conduct preflight due diligence under Sec. 91.103 to confirm preflight
availability; (2) operations that may encounter GPS interference; and
(3) operations that may be affected by a SAPT outage. Although it could
appear that an operator has not complied with the performance
requirements in Sec. 91.227 due to the circumstances described in this
document, the FAA would not consider these situations to constitute a
violation as such an application of the regulations would impose a
standard of conduct wholly outside the operator's control. The FAA
cautions that, for operators who have been notified by the FAA of
consistent and repeated ADS-B Out performance issues, conducting an
operation in accordance with the policy described herein without first
redressing the identified non-performance issue will be considered a
continuation of existing non-compliance with the performance
requirements.
A. Preflight Prediction for Certain Operators
As previously discussed, certain operators are required to use a
preflight availability prediction tool to predict the ability of an
aircraft to meet the performance requirements of Sec. 91.227(c)(1)(i)
and (iii) along a given route of flight. For exemption holders with SA-
On receivers, the preflight availability prediction must be performed
as part of an operator's preflight planning process. For non-exemption
holders with SA-On and SA-Aware receivers, the preflight availability
prediction tool is part of the preflight action necessary to ensure
rule compliance on a planned route of flight. If the predicted GPS
performance does not support the proposed flight, the operator may need
to adjust the flight plan accordingly to avoid the degraded GPS
performance.
After an operator receives a satisfactory preflight availability
prediction for an intended operation, there may be certain conditions
that warrant a subsequent prediction. For example, a change in
departure time or a change in the GPS satellite constellation as
indicated by a Notice to Airmen (NOTAM) may have an effect on the
predicted GPS performance for the intended operation. If an operator
becomes aware of a change that could result in degraded GPS performance
prior to receiving an initial ATC clearance for the intended route of
flight, the operator should--consistent with preflight action required
by Sec. 91.103--conduct a subsequent preflight availability prediction
for the planned flight to ensure that GPS performance is still
predicted to comply with the performance requirements of Sec.
91.227(c)(1)(i) and (iii).
The duty to conduct a subsequent preflight availability prediction
for an intended route of flight will cease once an operator receives an
ATC route clearance for the intended operation. More specifically, if
an operator receives a satisfactory preflight availability prediction
and an ATC route clearance for the intended operation, the FAA will
consider the operator as having exercised its due diligence in ensuring
the intended operation complies with the performance requirements in
Sec. 91.227. Therefore, upon receiving a satisfactory preflight
availability prediction and an ATC clearance for an intended route of
flight, the operator will be deemed to have complied with the preflight
availability prediction requirement and the performance requirements of
Sec. 91.227(c)(1)(i) and (iii).
The FAA recognizes that there are circumstances outside the
operator's control that may result in unanticipated changes to an
operator's planned route of flight, which may cause temporary degraded
GPS performance and technical noncompliance with Sec. 91.227(c)(1)(i)
and (iii). For example, ATC will continue to exercise its
responsibility for the safe and efficient movement of air traffic,
including changes to the routing of traffic to achieve those
objectives. In addition, a planned route of flight may be changed due
to environmental conditions, such as a thunderstorm, or an operator may
experience unexpected GPS degradations during flight. After an ATC
route clearance is obtained for the flight, the FAA does not expect an
operator to conduct a subsequent preflight availability prediction to
accommodate rerouting caused by ATC or environmental conditions.
The FAA notes that the policy described above applies only to those
operators who have exercised due diligence in complying with the
preflight availability prediction and
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ADS-B Out performance requirements. For example, if an operator fails
to conduct a preflight availability prediction for the operator's
intended operation and subsequently encounters degradation of GPS
performance that results in the aircraft falling below the performance
requirements of Sec. 91.227(c)(1)(i) and (iii), that operator will be
deemed to have violated the ADS-B rule--even if the operator's flight
were rerouted due to unforeseen circumstances.
When an operator performs a preflight availability prediction using
the FAA's SAPT, the SAPT retains a record of each transaction enabling
the FAA to confirm that an operator took preflight action. The FAA
recommends that operators using an alternate tool retain documentation
that verifies the completion of the satisfactory preflight availability
prediction for each intended route of flight. The FAA recommends that
the prediction should be done not more than 24 hours prior to the
planned departure. Predictions using SAPT to determine the availability
of backup surveillance per Exemption No. 12555 should be done within
the 3 hours prior to planned departure.
GPS Interference
There may be times when the GPS position source cannot meet the
required technical performance due to planned GPS interference. In the
event of a scheduled interference outage of GPS, the FAA will issue a
NOTAM that identifies the airspace and time periods that may be
affected by the interference. The affected area will frequently
encompass a large radius of ADS-B Out rule airspace. The FAA finds that
requiring operators to avoid the affected area would cause significant
disruption to air traffic in that vicinity. Furthermore, there is no
guarantee that these operators would experience actual interference and
a degradation in GPS performance in the area. For these reasons, the
FAA has determined that it would be impractical and not in the public
interest to require operators to avoid the affected area based on the
chance that an otherwise compliant flight could experience GPS
interference.
Accordingly, operators should proceed with their intended operation
if the only impediment to their operation is possible planned GPS
interference. Under this policy, an operator who is required to perform
a preflight availability prediction for the intended route of flight is
still required to obtain a satisfactory preflight availability
prediction. When a NOTAM identifies the airspace and time periods that
may be affected by GPS interference, an operator will not be required
to alter his or her route of flight to avoid the area based solely on
that NOTAM. As explained in the preamble to the final rule, if an
aircraft's avionics meet the performance requirements but unexpected
GPS degradations during flight inhibit the position source from
providing adequate accuracy and integrity, ATC will be alerted via the
aircraft's broadcasted data and services will be provided to that
aircraft using the backup strategy. If an operator encounters actual
GPS interference during their flight that results in a degradation of
ADS-B Out performance, the policy described in Part II above will
apply, provided the operator has taken the appropriate preflight
actions.
SAPT Outages
As noted, certain operators are required to use a preflight
availability prediction tool prior to a planned flight as a condition
of Exemption No. 12555. Other operators with SA-On and SA-Aware
equipment who do not hold this exemption exercise due diligence, as
required under Sec. 91.103, that a planned route of flight will comply
with ADS-B performance requirements underSec. 91.227(c)(1)(i) and
(iii). Some operators will use the FAA SAPT for this purpose. The FAA
intends that SAPT will be continuously available to operators. However,
because unexpected circumstances could lead to a SAPT outage, the
inability to access the tool could have an adverse impact on operators
with SA-On or SA-Aware GPS receivers. As previously noted in Advisory
Circular (AC) 90-114A CHG 1 Automatic Dependent Surveillance Broadcast
Operations, ATC will issue a NOTAM announcing when the SAPT is not
available.
The FAA understands that a SAPT outage prevents those operators who
hold relief under Exemption No. 12555 from confirming the availability
of back-up surveillance as required under the exemption's conditions
and limitations.\11\ It also reduces the ability of non-exemption
holders without their own preflight availability prediction tool to
determine that a particular operation will meet the performance
requirements prior to conducting an operation. The unavailability of
the SAPT for brief periods would result in operators having to choose
between conducting flights that might result in non-compliance and not
conducting an operation that would have complied with ADS-B Out rule
performance. The FAA does not intend to inhibit operators from
conducting otherwise permissible operations when the SAPT is
unavailable. As such, when there is a SAPT outage, the policy described
above will apply to operators who rely on the SAPT if their operation
falls below the performance requirements.
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\11\ The FAA anticipates that any outage would be of short
duration and any potential risk would be minimal because, concurrent
with the outage, GPS performance would have to fall below rule
values on the route of flight and radar coverage would have to be
unavailable at the same time and location.
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Implementation
Additional information for operators on the policy described in
this document will be contained in other FAA publications, including AC
90-114 and the Notices to Airmen publication.\12\
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\12\ The Notices to Airmen publication is published every 28
days. The latest two editions of the publication are available on
the FAA's website at https://www.faa.gov/air_traffic/publications/notices/.
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Summary
After January 1, 2020, unless otherwise authorized by ATC, all
aircraft operating in the airspace identified in Sec. 91.225 must
comply with the ADS-B Out performance requirements in Sec. 91.227. As
described above, however, there are circumstances outside of an
operator's control that may result in a temporary degradation of GPS
performance and an apparent violation of Sec. 91.227. An operator may
exercise due diligence in performing a preflight availability
prediction for its intended route of flight but experience rerouting by
ATC after obtaining an initial ATC route clearance, which may cause an
unanticipated degradation of performance. Additionally, an operator may
encounter actual GPS interference on its intended path of flight, which
would affect the ability of an aircraft to meet the performance
requirements of Sec. 91.227. Lastly, an operator may not be able to
complete a preflight availability prediction for its intended route of
flight due to the FAA's SAPT being out of service. As previously
explained, the FAA recognizes that these situations are outside of the
operator's control. Therefore, the FAA will not consider these events
to constitute noncompliance with Sec. 91.227 due to the circumstances
discussed in this document to the extent such an application would
impose a standard of conduct wholly outside the operator's control.
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Issued in Washington, DC, on June 26, 2019.
Teri L. Bristol,
Chief Operating Officer, Air Traffic Organization.
[FR Doc. 2019-14127 Filed 7-2-19; 8:45 am]
BILLING CODE 4910-13-P