[Federal Register Volume 87, Number 90 (Tuesday, May 10, 2022)]
[Rules and Regulations]
[Pages 27928-27931]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-09936]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 91

[Docket No. FAA-2022-0619]


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), Department of 
Transportation (DOT).

ACTION: Policy statement.

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SUMMARY: This action announces revisions to the FAA's policy on 
performance requirements for aircraft with Automatic Dependent 
Surveillance-Broadcast (ADS-B) Out equipment using the Selective 
Availability (SA)-Aware receivers in ADS-B rule airspace. The FAA will 
no longer expect aircraft with this equipment to perform a preflight 
availability prediction before operating in ADS-B rule airspace.

DATES: The policy described herein is effective May 10, 2022.

FOR FURTHER INFORMATION CONTACT: For technical information concerning 
this action, contact James Marks, Flight Technologies and Procedures 
Division, Aviation Safety, at (202) 267-8790.

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 
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 in Sec. Sec.  
91.225 (Automatic Dependent Surveillance-Broadcast (ADS-B) Out 
equipment and use) and 91.227 (Automatic Dependent Surveillance-
Broadcast (ADS-B) Out equipment performance requirements) of title 14 
of the Code of Federal Regulations (14 CFR) were promulgated under the 
authority described in Subtitle VII, Part A, Subpart I, Section 40103 
(Sovereignty and Use of Airspace) and in 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.
    In Sec.  91.227, the FAA set forth the ADS-B Out equipment 
performance requirements including accuracy and integrity performance 
standards. This policy statement is within the scope of the FAA's 
authority and informs operators equipped with Selective Availability 
(SA)-Aware receivers about a change to the FAA policy requiring they 
perform preflight availability predictions to ensure their avionics 
broadcast elements required by Sec.  91.227 as part of their Sec.  
91.103 (Preflight Action) obligations.

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 
position source, other aircraft avionics, and a ground 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, position, altitude, and velocity, 
through an onboard transmitter, which can be received by ADS-B ground 
stations (or satellite 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.
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    \2\ GPS is a specific type of Global Navigation Satellite System 
(GNSS).
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FAA ADS-B Service Availability Prediction Tool (SAPT)

    The ADS-B Service Availability Prediction Tool (SAPT) is a 
preflight resource developed by the FAA, that predicts the ability of 
standard GPS receivers 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 
(e.g., GPS receiver) to meet ADS-B performance requirements based on 
the type of GPS receiver (FAA TSOs C129, C129a, C145c/C146c, and C196) 
and the predicted status of the GPS constellation. The SAPT also 
evaluates if backup surveillance is available where position source 
performance is predicted to fall below requirements.\3\ The ADS-B SAPT 
is primarily intended for pilots, dispatchers, and commercial operators 
to verify their predicted position source performance before flight and 
ensure compliance with the ADS-B Out rule.\4\
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    \3\ 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.
    \4\ 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

[[Page 27929]]

A4A member airlines, for an exemption from the Navigation Accuracy 
Category for Position (NACp) and Navigation Integrity Category (NIC) 
requirements of the rule. A key premise of the exemption was an 
understanding that certain position sources were more likely than 
others to not perform at the required level established by the ADS-B 
Out rule. In August 2015, the Administrator issued Exemption No. 
12555,\5\ 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 12555 permits operation of aircraft equipped with TSO-
C129 (SA-On) and TSO-C196 (SA-Aware) 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. 
Additionally, Exemption 12555 does not require aircraft equipped with 
SA-Aware GPS receivers to use a preflight availability prediction tool.
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    \5\ Regulatory Docket Number FAA-2015-0971 (FAA Exemption No. 
12555) at https://www.regulations.gov/docket/FAA-2015-0971.
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2019 Policy Statement

    On July 3, 2019, the FAA published a Federal Register document with 
its policy on performance requirements for operators equipped with ADS-
B Out, including those equipped with a SA-Aware position source.\6\ The 
FAA found that Wide Area Augmentation System (WAAS) \7\ was the only 
GPS position source that consistently provided the equivalent 
availability to radar at 99.9 percent availability.\8\ The FAA also 
believed that SA-Aware receivers could meet a similar 99.9 percent 
availability as long as there was no significant reduction in the GPS 
satellite constellation. Given since the data at the time of 
publication of the 2019 policy was limited, the FAA determined that 
aircraft equipped with GPS position sources such as Selective Ability-
On (SA-On or SA-Aware were more likely to experience performance 
outages that limited their access to the airspace defined in the ADS-B 
rule.
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    \6\ Statement of Policy on Performance Requirements for 
Operators of Aircraft That are Equipped with ADS-B Out, 84 FR 31713 
(July 3, 2019).
    \7\ WAAS is a regional a space-based augmentation system (SBAS) 
operated by the FAA.
    \8\ FAA also determined that certain GPS tightly integrated with 
inertial navigation systems would also provide 99.9 percent 
availability.
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    The 2019 policy statement reiterated Sec.  91.103's requirement 
that pilots become familiar with all available information concerning a 
flight. The FAA explained that 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. Therefore, these operators were 
required to confirm that a planned route of flight would comply with 
the ADS-B performance requirements in Sec.  91.227(c)(1)(i) and (iii). 
Operators could use any reliable preflight prediction tool, with the 
SAPT providing a comprehensive and reliable preflight prediction for 
operators. The policy statement explained that for operators who had 
been notified by the FAA of consistent and repeated ADS-B Out 
performance issues, conducting an operation in accordance with the 
policy without first redressing the identified non-performance issue 
would be considered a continuation of the non-compliance with the 
performance requirements. Also, if an operator failed to conduct a 
preflight availability prediction for the operator's intended operation 
and subsequently encountered degradation of GPS performance that 
resulted in the aircraft falling below the performance requirements of 
Sec.  91.227(c)(1)(i) and (iii), that operator would be deemed to have 
violated the ADS-B rule--even if the operator's flight were to be 
rerouted due to unforeseen circumstances.

Performance Based Operations Aviation Rulemaking Committee (PARC) 
Exemption 12555 Action Team

    In August 2020, the FAA tasked the PARC to form an action team 
comprised of industry stakeholders and FAA subject matter experts to 
report on the following:
    1. Identify barriers and appropriate mitigations to air carrier 
Exemption 12555 equipage plans that lead to full compliance with Sec.  
91.227; and
    2. Describe status of applicable equipment availability relative to 
achievement of operator equipage plans toward end state of Exemption 
12555 on December 31, 2024.
    The PARC provided a forum for the U.S. aviation community to 
discuss, prioritize, and resolve issues, provide direction for U.S. 
flight operations criteria and produce U.S. consensus positions for 
global harmonization on performance-based airspace operations. The PARC 
action team requested that the FAA provide a report on ADS-B Out 
equipped aircraft with approved position sources and their ability to 
meet the equivalent operational availability of radar (99.9% or greater 
availability requirement). In addition to the 4 years of data used to 
support the 2019 policy document, an additional 3 years of position 
source performance data was given to the PARC action team to analyze.
    FAA analysis and prior modeling in support of the ADS-B Aviation 
Rulemaking Committee indicated that the critical ADS-B quality 
parameter was the NIC parameter defined in Sec.  91.227(c)(1)(iii). FAA 
data indicated a historical operational availability with regard to 
required NIC rule performance for the following ADS-B position source 
types:
--SA-On GPS receivers achieved between 98-99% operational availability;
--SA-Aware GPS receivers achieved 99.9%, or greater, operational 
availability; and
--Satellite-Based-Augmentation System (SBAS) receivers achieved 99.9%, 
or greater, operational availability

    In consideration of these findings, the PARC Exemption 12555 action 
team recommended removing the requirement for aircraft equipped with 
SA-Aware GPS receivers to use a preflight availability prediction tool 
(e.g., the Service Availability Prediction Tool (SAPT)).
    The FAA agrees that the demonstrated performance of SA-Aware GPS 
receivers has been equivalent to, or better than, a single radar since 
the FAA began monitoring ADS-B performance in 2015. Years of additional 
data and assurances that the GPS constellation will remain at current 
levels have given the FAA confidence that SA-Aware GPS receivers will 
consistently provide the availability required by the ADS-B regulation. 
The FAA accepts any residual risk associated with SA-Aware GPS receiver 
performance falling below the regulatory requirement. As such, the FAA 
is adopting the subject PARC Exemption 12555 action team recommendation 
and is revising preflight policy issued in 2019 for aircraft equipped 
with SA-Aware GPS receivers in this document.

II. Discussion of the Policy

Preflight Availability Prediction Policy

    Given the demonstrated performance of SA-Aware (TSO-C196) GPS 
receivers over a seven-year monitoring period and the expectation that 
the GPS constellation will provide coverage at current levels for the 
foreseeable future, the FAA now finds that such GPS receivers 
consistently provide an equivalent availability to that of a single 
radar at 99.9 percent operational availability. Aircraft equipped with 
SA-Aware GPS receivers during periods of GPS constellation degradation 
that negatively impact the ability of ADS-B

[[Page 27930]]

Out equipment to meet performance requirements associated with the rule 
will be deemed compliant with the ADS-B Out rule requirements. 
Therefore, the operators of aircraft equipped with position sources 
that meet the performance requirements of TSO-C196 (SA-Aware) is not 
required to perform a preflight availability prediction to fulfill 
their Sec.  91.103 due diligence obligation. For aircraft equipped with 
GPS receivers that do not meet the performance requirements of TSO-196 
or TSO-C145/146, the operator must run a preflight prediction.
    Due to the reduced performance of SA-On receivers relative to ADS-B 
rule requirements, operators of aircraft with these receivers are 
expected to use a preflight availability prediction tool to predict the 
ability of an aircraft position source to meet the performance 
requirements of Sec.  91.227(c)(1)(i) and (iii) along a given route of 
flight. For non-exemption holders with SA-On receivers and exemption 
holders after expiration of Exemption 12555, a preflight availability 
prediction tool should be used to comply with Sec.  91.103 due 
diligence requirements for a planned route of flight in ADS-B rule 
airspace. If the predicted SA-On receiver performance does not support 
compliance with Sec.  91.227 for the proposed flight, the FAA expects 
operators to adjust the flight plan (e.g., departure time, route) as 
needed to avoid any areas or time periods predicted with degraded GPS 
performance. Holders of Exemption 12555 are expected to follow the 
conditions of that exemption until it expires on December 31, 2024.
    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 satellite constellation as indicated 
by a Notice to Air Missions (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 under Sec.  91.103 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 required in Sec.  91.103 by 
performing a preflight availability prediction. For example, if an 
operator fails to conduct a required preflight availability prediction 
for the operator's intended operation and subsequently encounters 
technical non-compliance with 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 tool, 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 12555 
should be done within the 3 hours prior to a 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 anticipated ADS-B noncompliance would be due to the 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 above will apply provided 
the operator has taken the appropriate preflight actions.

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SAPT Outages

    As noted, certain operators are required to use a preflight 
availability prediction tool prior to a planned flight. 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 receivers. As 
previously noted in Advisory Circular (AC) 90-114, ADS-B 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.\9\ 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 or not 
conducting an operation that might 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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    \9\ 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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III. Summary

    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. Under the FAA's revised 
policy, aircraft equipped with SA-Aware GPS receivers described in this 
document are not required to perform a preflight service availability 
prediction, including those aircraft not covered by Exemption 12555. 
Aircraft equipped with SA-On receivers should continue performing 
preflight availability predictions and can use the guidance contained 
in AC 90-114, ADS-B Operations, when conducting preflight actions for 
operations planned within airspace described in Sec.  91.225. Holders 
of Exemption 12555 must continue to meet the conditions and limitations 
associated with the exemption. Holders of Exemption 12555 should revise 
applicable equipage plans to reflect any changes affected by policy 
contained in this document and submit revised plans to the FAA per 
conditions specified by the exemption.
    As described in this document, 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 take legal enforcement 
action for apparent 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.

IV. Effective Date

    Policy in this document is effective immediately and supersedes 
policy contained in FRN Docket No. FAA-2019-0539. Additional 
information on the policy described in this document will be contained 
in the next revision of AC 90-114, ADS-B Operations.

    Issued in Washington, DC, on May 4, 2022.
Gregory E. Schwab,
Acting Chief of Staff, Air Traffic Organization.
[FR Doc. 2022-09936 Filed 5-9-22; 8:45 am]
BILLING CODE 4910-13-P


