[Federal Register Volume 88, Number 88 (Monday, May 8, 2023)]
[Proposed Rules]
[Pages 29554-29555]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-09622]
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Proposed Rules
Federal Register
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This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 88, No. 88 / Monday, May 8, 2023 / Proposed
Rules
[[Page 29554]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 21
[Docket No. FAA-2023-0938]
Proposed Policy Statement; Demonstration of Radio Altimeter
Tolerant Aircraft
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notification of availability; request for comments.
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SUMMARY: This document announces the availability of a draft Policy
Statement PS-AIR-600-39-01, Demonstration of Radio Altimeter Tolerant
Aircraft. The FAA invites public comment on PS-AIR-600-39-01.
DATES: The FAA must receive comments on this document on or before June
7, 2023.
ADDRESSES: You may send comments identified by docket number FAA-2023-
0938 using any of the following methods:
[squ] Federal eRulemaking Portal: Go to www.regulations.gov and
follow the instructions for submitting comments electronically.
[squ] Mail: U.S. Department of Transportation, Docket Operations,
M-30, 1200 New Jersey Avenue SE, Room W12-140, West Building Ground
Floor, Washington, DC 20590-0001.
[squ] Hand Delivery: Deliver to Mail address above between 9 a.m.
and 5 p.m., Monday through Friday, except Federal holidays.
[squ] Fax: (202) 493-2251.
Docket: Background documents or comments received may be read at
www.regulations.gov at any time. Follow the online instructions for
accessing the docket or go to the Docket Operations in Room W12-140 of
the West Building Ground Floor at 1200 New Jersey Avenue SE,
Washington, DC, between 9 a.m., and 5 p.m., Monday through Friday,
except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Barbara Clark, Aviation Safety
Specialist, Avionics and Electrical Systems Section, 800 Independence
Ave. SW, DC 20591; telephone: 817-222-5390; email:
[email protected].
SUPPLEMENTARY INFORMATION:
Privacy: The FAA will post all comments it receives, without
change, to www.regulations.gov, including any personal information the
commenter provides. Using the search function of the docket website,
anyone can find and read the electronic form of all comments received
into any FAA docket, including the name of the individual sending the
comment (or signing the comment for an association, business, labor
union, etc.). DOT's complete Privacy Act Statement can be found in the
Federal Register published on April 11, 2000 (65 FR 19477-19478), as
well as at https://DocketsInfo.dot.gov.
Comments Invited
The FAA invites interested parties to take part in the development
of the proposed policy statement by sending written comments to an
address listed under ADDRESSES. Include Docket No. FAA-2023-0938;
Policy No. PS-AIR-600-39-01 at the beginning of your comments. The most
helpful comments reference a specific portion of the proposal, explain
the reason for any recommended change, and include supporting data. The
FAA will consider all comments received by the closing date and may
amend the proposal because of those comments.
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
regulations.gov, including any personal information you provide. The
agency will also post a report summarizing each substantive verbal
contact received about this proposed policy.
Confidential Business Information
CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this notice contain
commercial or financial information that is customarily treated as
private, that you actually treat as private, and that is relevant or
responsive to this notice, it is important that you clearly designate
the submitted comments as CBI. Please mark each page of your submission
containing CBI as ``PROPIN.'' The FAA will treat such marked
submissions as confidential under the FOIA, and they will not be placed
in the public docket of this notice. Submissions containing CBI should
be sent to the individual listed under FOR FURTHER INFORMATION CONTACT.
Any commentary that the FAA receives that is not specifically
designated as CBI will be placed in the public docket for this notice.
Background
The current performance standards for radio altimeters (also known
as radar altimeters) are based on the presumption that no occupancy of
an adjacent radio frequency spectrum would cause interference with
radio altimeters. During 2021, the radio frequency operating
environment surrounding radio altimeters substantially changed when
wireless telecommunication service providers began offering 5G C-Band
services near the 4.2-4.4 GHz band, which is reserved for aviation
radio altimeters. The FAA subsequently determined that radio altimeters
cannot be relied upon to perform their intended function if they
experience interference from 5G wireless broadband operations in the C-
Band.
Deployment of the new 5G C-Band services prompted the FAA to
address the risks posed by radio frequency (RF) interference to radio
altimeters. On December 7, 2021, the FAA issued AD 2021-23-12 \1\ for
transport and commuter category airplanes equipped with a radio
altimeter and AD 2021-23-13 \2\ for helicopters equipped with a radio
altimeter. AD 2021-23-12 and AD 2021-23-12 prohibit certain flight
operations requiring radio altimeter data when flying in the presence
of 5G C-Band interference as identified by Notices to Air Missions
(NOTAMs). In response to AD 2021-23-12, the aviation industry developed
a method to show compatibility with 5G emissions
[[Page 29555]]
in the United States national airspace system for the initial 5G
deployment, which was limited to 3.7-3.8 GHz, and the 5G spurious
emissions in the radio altimeter band (4.2-4.4 GHz). The FAA accepted
this method as support for proposals for alternative methods of
compliance (AMOCs) with AD 2021-23-12 and AD 2021-23-13. These AMOCs
used standardized assessment parameters, values, and methods to
estimate an installed altimeter system protection radii or distance.
Aircraft with an altimeter operating beyond this distance from all 5G
base stations would not expect deleterious effects from RF
incompatibility and indeed could depend upon the radio altimeter system
to fully perform its intended function. These AMOCs were based on
interference thresholds of specific individual radio altimeter
transceivers. That is, each transceiver was tested to benchmark their
performance in the presence of out-of-band and in-band C-Band signals.
The thresholds were then modified and tailored to installation factors
specific to the installed platform (e.g., measured antenna gains and
line losses). These values were then used to determine the necessary
mitigations to protect the airport airspace most critical for the
safety of operations. The mitigations included actions by wireless
providers as well as flight limitations imposed by the FAA for the
airspace areas identified by NOTAM, unless operating under an approved
AMOC.
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\1\ Amendment 39-21810, 86 FR 69984, December 9, 2021.
\2\ Amendment 39-21811, 86 FR 69992, December 9, 2021.
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On January 6, 2023, the FAA issued a notice of proposed rulemaking
(NPRM) proposing to supersede AD 2021-23-12.\3\ On April 5, 2023, the
FAA issued an NPRM proposing to supersede AD 2021-23-13.\4\ The flight
limitations in the new proposed ADs would depend on whether an aircraft
has a radio altimeter that demonstrates certain tolerances using a
method approved by the FAA.
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\3\ Docket No. FAA-2022-1647, 88 FR 1520 (January 11, 2023).
\4\ Docket No. FAA-2023-0668, 88 FR 21931 (April 12, 2023).
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Proposed Policy Statement
This proposed policy would provide guidance for operators and
manufacturers to demonstrate an aircraft is a radio altimeter tolerant
aircraft, under the proposed definition in the NPRMs.
You may review the proposed policy statement at www.regulations.gov
in Docket No. FAA-2023-0938; or on the FAA's website at www.faa.gov/aircraft/draft_docs/.
Issued on May 2, 2023.
Michael Linegang,
Acting Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2023-09622 Filed 5-5-23; 8:45 am]
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