[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

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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


