Published 2026-06-30 · Federal Register document 2026-13207
Airworthiness Directives; The Boeing Company Airplanes
Publication summary
The FAA is adopting a new airworthiness directive (AD) for all The Boeing Company Model 747-100, -100B, -100B SUD, -200B, -200C, - 200F, -300, -400, -400D, and -400F series airplanes. This AD was prompted by the determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 3.7-3.98 GHz frequency band (5G Lower C-Band) while operating in Canadian airspace, and a determination that during takeoff, approach, landings, and go-arounds, as a result of this interference, certain airplane systems may not properly function, resulting in increased flightcrew workload while on approach with the flight director, autothrottle, or autopilot engaged, which could result in reduced ability of the flightcrew to maintain safe flight and landing of the airplane. This AD requires revising the existing airplane flight manual (AFM) to incorporate limitations prohibiting certain operations requiring radio altimeter data when operating in Canadian airspace. The FAA is issuing this AD to address the unsafe condition on these products.
Why this record is shown
Source: Federal Register annual FAA metadata. Acquired 2026-10-11T15:01:38.908778+00:00. The title, summary and date are source facts.
- Source revision
- federal_register_ad_metadata_2026-346456b685abaa6b
- Source row
- results[172]
- Raw source SHA-256
- 346456b685abaa6b551902467a6384e655145a0a63f9cc15222fde6cb778bdfc
Final-rule publication
Recorded publication clauses
- AD identifier printed in this edition
- 2026-13-14
- Effective date printed in this edition
- 2026-07-01
Read 12 complete recorded clauses
Effective Date
(a) Effective Date
This airworthiness directive (AD) is effective July 1, 2026.
Exact source excerpt. Text positions 22878–22964, end exclusive, in the original decoded publication. SHA-256: 63b12af81d893d5686e92d69bea62daaa244f6d607bd23d001a4c9cb1c54f20b
Affected ADs
(b) Affected ADs
None.
Exact source excerpt. Text positions 22964–22993, end exclusive, in the original decoded publication. SHA-256: 871a4afc60ceeae06e8010585055188633d616078500c45937092bfe892239c0
Applicability wording · Applicability
(c) Applicability
This AD applies to all The Boeing Company Model 747-100, -100B, -
100B SUD, -200B, -200C, -200F, -300, -400, -400D, and -400F series
airplanes, certificated in any category.
Exact source excerpt. Text positions 22993–23192, end exclusive, in the original decoded publication. SHA-256: 2d0a953c0791cdf879eeead755d5ee93c3a8129fb9802f033ad2c0b889064aa9
Subject
(d) Subject
Air Transport Association (ATA) of America Code 34, Navigation.
Exact source excerpt. Text positions 23192–23274, end exclusive, in the original decoded publication. SHA-256: 0542bcd80d4296f1663f9c1a9ee6733c7599b54c556ebcd2abd87a0d6015adff
Unsafe Condition
(e) Unsafe Condition
This AD was prompted by the determination that radio altimeters
cannot be relied upon to perform their intended function if they
experience interference from wireless broadband operations in the 3.7-
3.98 GHz frequency band (5G Lower C-Band) when operating in Canadian
airspace, and the determination that during takeoff, approach,
landings, and go-arounds, as a result of this interference, certain
airplane systems may not properly function, resulting in increased
flightcrew workload while on approach with the flight director,
autothrottle, or autopilot engaged. The FAA is issuing this AD to
address 5G Lower C-Band interference that could result in increased
flightcrew workload and could lead to reduced ability of the flightcrew
to maintain safe flight and landing of the airplane.
Exact source excerpt. Text positions 23274–24101, end exclusive, in the original decoded publication. SHA-256: cdb25a8de79515d40f875beda997a5a733099c10ff9835f292289de025e94c9b
Compliance
(f) Compliance
Comply with this AD within the compliance times specified, unless
already done.
Exact source excerpt. Text positions 24101–24203, end exclusive, in the original decoded publication. SHA-256: abbabaaf05573998de1d97fbb30ea4c00462eeb0a61e63718978c9d279c57885
Definitions
(g) Definitions
(1) For purposes of this AD, a ``radio altimeter tolerant
airplane'' is one for which the radio altimeter, as installed,
demonstrates the tolerances specified in paragraphs (g)(1)(i) and (ii)
of this AD, using a method approved by the FAA. No actions are required
by this AD for radio altimeter tolerant airplanes.
(i) Tolerance to radio altimeter interference, for the fundamental
emissions (3.7-3.98 GHz), at or above the power spectral density (PSD)
curve threshold specified in figure 1 to paragraph (g)(1)(i) of this
AD.
[GRAPHIC] [TIFF OMITTED] TR30JN26.003
(ii) Tolerance to radio altimeter interference, for the spurious
emissions (4.2-4.4 GHz), at or above the PSD curve threshold specified
in figure 2 to paragraph (g)(1)(ii) of this AD.
[[Page 39457]]
[GRAPHIC] [TIFF OMITTED] TR30JN26.004
(2) For purposes of this AD, a ``non-radio altimeter tolerant
airplane'' is one for which the radio altimeter, as installed, does not
demonstrate the tolerances specified in paragraphs (g)(1)(i) and (ii)
of this AD.
Exact source excerpt. Text positions 24203–25270, end exclusive, in the original decoded publication. SHA-256: 5905ee3dc3f7b7d1c6282ff6873c583c343c0ab563d59394e67b6c1ac83fa7cb
Airplane Flight Manual (AFM) Revision
(h) Airplane Flight Manual (AFM) Revision
For non-radio altimeter tolerant airplanes: Before further flight
in Canadian airspace, do the actions specified in paragraphs (h)(1) and
(2) of this AD.
(1) Revise the Limitations Section of the existing AFM to include
the information specified in figure 3 to paragraph (h)(1) of this AD.
This may be done by inserting a copy of figure 3 to paragraph (h)(1) of
this AD into the existing AFM.
[[Page 39458]]
[GRAPHIC] [TIFF OMITTED] TR30JN26.005
(2) Revise the Operating Procedures Section of the existing AFM to
include the information specified in figure 4 to paragraph (h)(2) of
this AD. This may be done by inserting a copy of figure 4 to paragraph
(h)(2) of this AD into the existing AFM. An AFM with an Operating
Procedures Section that complies with paragraph (h)(2) of AD 2023-12-
14, Amendment 39-22472 (88 FR 40003, June 21, 2023) is acceptable for
compliance with the requirements of this paragraph of this AD.
[GRAPHIC] [TIFF OMITTED] TR30JN26.006
Exact source excerpt. Text positions 25270–26299, end exclusive, in the original decoded publication. SHA-256: f7c716baac9687b4f2dd728c4c53f2bb1da23eb9fef33bdca52b8dfb821ab059
Terminating Action for AFM Revision
(i) Terminating Action for AFM Revision
(1) Modifying the airplane from a non-radio altimeter tolerant
airplane to a radio altimeter tolerant airplane terminates the
limitations in paragraph (h)(1) of this AD and the operating procedures
in paragraph (h)(2) of this AD for that airplane.
(2) After modifying the airplane to a radio altimeter tolerant
airplane, the limitations in paragraph (h)(1) of this AD and the
operating procedures in paragraph (h)(2) of this AD may be removed from
the AFM.
Exact source excerpt. Text positions 26299–26812, end exclusive, in the original decoded publication. SHA-256: db5dfed3c736a86aeb2646441440e941bd0fb132d8370f9aa4913eb8c4e6b6a8
Alternative Methods of Compliance (AMOCs)
(j) Alternative Methods of Compliance (AMOCs)
(1) The Manager, AIR-520, Continued Operational Safety Branch, FAA,
has the
[[Page 39459]]
authority to approve AMOCs for this AD, if requested using the
procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send
your request to your principal inspector or responsible Flight
Standards Office, as appropriate. If sending information directly to
the manager of AIR-520, Continued Operational Safety Branch, send it to
the attention of the person identified in paragraph (k) of this AD and
email to: [email protected].
(2) Before using any approved AMOC, notify your appropriate
principal inspector, or lacking a principal inspector, the manager of
the responsible Flight Standards Office.
(3) The following AMOCs approved previously for AD 2023-12-14,
Amendment 39-22472 (88 FR 40003, June 21, 2023) are approved as AMOCs
for paragraph (g)(1) of this AD: FAA AMOC letters 720-23-00133, 720-23-
00137, 720-23-00138, and 720-23-00169.
Exact source excerpt. Text positions 26812–27830, end exclusive, in the original decoded publication. SHA-256: 4466ca888ea5a12a9375334d62ee25c5268235f360de1da2377c50855f166ad4
Additional Information
(k) Additional Information
For more information about this AD, contact Ken Fairhurst,
Continued Operational Safety Technical Advisor, FAA, 2200 South 216th
St., Des Moines, WA 98198; phone: 817-222-5390; email:
[email protected].
Exact source excerpt. Text positions 27830–28069, end exclusive, in the original decoded publication. SHA-256: c0662d25eb35500a5d133490c5906345171a49d717639c10ba7172a11a496010
Material Incorporated by Reference
(l) Material Incorporated by Reference
None.
Exact source excerpt. Text positions 28069–28120, end exclusive, in the original decoded publication. SHA-256: 33b5654a42b7710d6e34eeb5d6f69110405cc721191b2e466fa582ff6e507325
No replacement link has been established from this edition. The complete historical rule chain and current legal effect remain unknown.
Find all recorded historical references to AD 2026-13-14 · 0 printed reference observations in this pinned collection.
These are observations from one dated publication. Current legal status is unknown; aircraft applicability, installed configuration, compliance and burden require separate evidence. Missing or unparsed conditions remain unknown.
Why these observations are shown
They were extracted offline from the same immutable official HTML source as the complete recorded text. The dated source wording, original text coordinates and exact quote digests are retained. PDF/text agreement and current regulatory effect have not been qualified.
Observation revision: whole-ad-publication-clause-observations-1.0.1. Text SHA-256: 2ae1065583ef5951d1e9e722f3fff4d4702938948505cb7d12a691d8128f6d38. Source manifest: c54a5647cf7ebca5f28efe6d96d6628af93fc044adda66818109904a09acfc9f.
Official source · 2026-06-30
Publication text
This is the complete recorded text of this dated publication.
Current legal effect is unknown. Aircraft applicability, installed configuration and compliance require separate evidence. PDF/text agreement has not been evaluated.
Read the complete official publication text
[Federal Register Volume 91, Number 124 (Tuesday, June 30, 2026)]
[Rules and Regulations]
[Pages 39452-39459]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-13207]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2026-7205; Project Identifier AD-2026-00549-T;
Amendment 39-23397; AD 2026-13-14]
RIN 2120-AA64
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
[[Page 39453]]
ACTION: Final rule; request for comments.
-----------------------------------------------------------------------
SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
The Boeing Company Model 747-100, -100B, -100B SUD, -200B, -200C, -
200F, -300, -400, -400D, and -400F series airplanes. This AD was
prompted by the determination that radio altimeters cannot be relied
upon to perform their intended function if they experience interference
from wireless broadband operations in the 3.7-3.98 GHz frequency band
(5G Lower C-Band) while operating in Canadian airspace, and a
determination that during takeoff, approach, landings, and go-arounds,
as a result of this interference, certain airplane systems may not
properly function, resulting in increased flightcrew workload while on
approach with the flight director, autothrottle, or autopilot engaged,
which could result in reduced ability of the flightcrew to maintain
safe flight and landing of the airplane. This AD requires revising the
existing airplane flight manual (AFM) to incorporate limitations
prohibiting certain operations requiring radio altimeter data when
operating in Canadian airspace. The FAA is issuing this AD to address
the unsafe condition on these products.
DATES: This AD is effective July 1, 2026.
The FAA must receive comments on this AD by August 14, 2026.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to regulations.gov. Follow
the instructions for submitting comments.
<bullet> Fax: 202-493-2251.
<bullet> Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
<bullet> Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
AD Docket: You may examine the AD docket at regulations.gov by
searching for and locating Docket No. FAA-2026-7205; or in person at
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. The AD docket contains this final rule, any
comments received, and other information. The street address for Docket
Operations is listed above.
FOR FURTHER INFORMATION CONTACT: Ken Fairhurst, Continued Operational
Safety Technical Advisor, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 817-222-5390; email: [email protected].
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written data, views, or arguments
about this final rule. Send your comments using a method listed under
the ADDRESSES section. Include Docket No. FAA-2026-7205 and Project
Identifier AD-2026-00549-T at the beginning of your comments. The most
helpful comments reference a specific portion of the final rule,
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 this final rule 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 final rule.
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 AD 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 AD, 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 AD. Submissions containing CBI should be sent to Ken
Fairhurst, Continued Operational Safety Technical Advisor, FAA, 2200
South 216th St., Des Moines, WA 98198; phone: 817-222-5390; email:
[email protected]. Any commentary that the FAA receives that is
not specifically designated as CBI will be placed in the public docket
for this rulemaking.
Background
The FAA issued AD 2021-23-12, Amendment 39-21810 (86 FR 69984,
December 9, 2021) (AD 2021-23-12), for all transport and commuter
category airplanes equipped with a radio altimeter. AD 2021-23-12 was
prompted by a determination that radio altimeters cannot be relied upon
to perform their intended function if they experience interference from
wireless broadband operations in the 5G Lower C-Band, which is close to
the frequency bands used by radio altimeters (4.2-4.4 GHz). AD 2021-23-
12 required revising the limitations section of the existing AFM to
incorporate limitations prohibiting certain operations requiring radio
altimeter data when in the presence of 5G Lower C-Band interference as
identified by Notices to Air Missions (NOTAMs). The agency issued AD
2021-23-12 because radio altimeter anomalies that are undetected by the
automation or pilot, particularly close to the ground (e.g., landing
flare), could lead to loss of continued safe flight and landing.
The FAA subsequently identified an additional hazard presented by
5G Lower C-Band interference on Boeing Model 747-100, -100B, -100B SUD,
-200B, -200C, -200F, -300, -400, -400D, and -400F series airplanes and
issued AD 2022-06-16, Amendment 39-21982 (87 FR 14780, March 16, 2022)
(AD 2022-06-16). AD 2022-06-16 was prompted by the unsafe condition in
AD 2021-23-12, as well as a determination that, during takeoff,
approach, landings, and go-arounds, as a result of interference from
the 5G Lower C-Band, certain airplane systems may not properly
function, resulting in increased flightcrew workload while on approach
with the flight director, autothrottle, or autopilot engaged, which
could result in reduced ability of the flightcrew to maintain safe
flight and landing of the airplane. AD 2022-06-16 required revising the
limitations and operating procedures sections of the existing AFM to
incorporate specific operating procedures for takeoff, instrument
landing system (ILS) approaches, non-precision approaches, and go-
around and missed approaches, when in the presence of 5G Lower C-Band
interference as identified by NOTAMs.
After the FAA issued AD 2021-23-12 and AD 2022-06-16, the agency
determined that additional limitations were needed due to the continued
deployment of new 5G Lower C-Band base stations whose signals were
expected to cover most of the contiguous U.S., as well as the
determination that radio altimeter anomalies could lead to increased
flightcrew workload and flightcrew desensitization to warnings.
Therefore, the FAA issued AD 2023-10-02, Amendment 39-22438 (88 FR
34065, May 26, 2023) (AD 2023-10-02), to supersede AD 2021-23-12, and
the FAA
[[Page 39454]]
issued AD 2023-12-14, Amendment 39-22472 (88 FR 40003, June 21, 2023)
(AD 2023-12-14), to supersede AD 2022-06-16.
Currently, AD 2023-12-14 requires revising the limitations section
of the existing AFM to incorporate limitations for dispatch or release
to airports, and takeoff, approach, landing, and go-around on runways
at all airports in the entire contiguous U.S. airspace instead of only
in areas identified by NOTAM; however, AD 2023-12-14 permits radio
altimeter tolerant airplanes to perform these operations at 5G Lower C-
Band mitigated airports as identified in an FAA Domestic Notice.
Actions Since AD 2023-12-14 Was Issued
Since the FAA issued AD 2023-12-14, Transport Canada, which is the
aviation authority for Canada, issued AD CF-2024-14, dated May 15, 2024
(Transport Canada AD CF-2024-14), to correct an unsafe condition for
all transport and commuter category airplanes with a radio altimeter.
Transport Canada AD CF-2024-14 states that in July 2023, Innovation,
Science and Economic Development Canada (ISED), Canada's spectrum
regulator, published Standard Radio System Plans (SRSP)-520 Issue 3 \1\
and Radio Standard Specifications (RSS)-192 Issue 5,\2\ which define
the spectrum environment for the 3.45-3.90 GHz frequency band in
Canada. Transport Canada AD CF-2024-14 further states that spectrum
auctions for the 3.45-3.65 GHz and the 3.65-3.9 GHz band were completed
in 2021 and 2023, respectively.
---------------------------------------------------------------------------
\1\ https://ised-isde.canada.ca/site/spectrum-management-telecommunications/en/devices-and-equipment/standard-radio-system-plans/srsp-520-technical-requirements-fixed-andor-mobile-systems-including-flexible-use-broadband-systems.
\2\ https://ised-isde.canada.ca/site/spectrum-management-telecommunications/en/devices-and-equipment/radio-equipment-standards/radio-standards-specifications-rss/rss-192-flexible-use-broadband-equipment-operating-band-3450-3900-mhz.
---------------------------------------------------------------------------
In July 2023, ISED implemented measures to mitigate Lower C-Band
interference to radio altimeters, which provide the Canadian airspace
greater protection from 5G Lower C-Band interference to radio
altimeters as compared to the Lower C-Band environment in the
contiguous U.S. airspace. These measures include exclusion and
protection zones and airport effective isotropic radiated power (EIRP)
elevation mask (a restriction that requires nearby cell tower signals
to be angled downward so they do not interfere with aircraft
altimeters) at certain airport runways covering the majority of air
traffic in Canada, as well as nationwide reduced fundamental power
emissions based on the degree of antenna uptilt above the horizon to
minimize emissions from 5G base stations toward aircraft.
In late March 2026, Transport Canada notified the FAA that,
beginning July 1, 2026, changes in the 5G Lower C-band protection
mitigations established by ISED in 2023 would result in a more severe
5G interference environment in the Canadian airspace. Exclusion and
protection zones at airports will no longer exist and updates to the
airport EIRP elevation mask, nationwide tilt restriction, emitter
height limitation and reduced spurious emissions will only protect
airplanes that are radio altimeter tolerant. The change in mitigations
will result in an unsafe condition in the Canadian 5G interference
environment.
Transport Canada determined that radio altimeters cannot be relied
upon to perform their intended function if they experience interference
from wireless broadband operations in the 3.45-3.98 GHz frequency band.
Transport Canada based its determination on the same unsafe condition
found by the FAA in AD 2023-10-02. As a result, Transport Canada AD CF-
2024-14 requires revising the limitations section of the existing AFM
to incorporate limitations prohibiting certain operations requiring
radio altimeter data, due to the presence of 5G Lower C-Band
interference, while operating in Canadian airspace. As terminating
action for the operating limitations, Transport Canada AD CF-2024-14
provides that operators may upgrade their radio altimeters to
demonstrate the tolerances for emissions as specified in Transport
Canada AD CF-2024-14.
Boeing subsequently conducted an analysis of the expected changes
in the 5G Lower C-Band environment in Canada and the effects of
interference with radio altimeters with respect to the Boeing fleet. In
May 2026, Boeing reported that certain airplane configurations will not
demonstrate tolerance to radio altimeter interference in the new 5G
environment in Canada. Therefore, based on this information, the FAA
determined that the unsafe condition identified in AD 2023-12-14 exists
for Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, -400, -
400D, and -400F series airplanes when operating in the Canadian
airspace. As a result, operating limitations similar to the limitations
required by AD 2023-12-14 are necessary.
The FAA is issuing this AD to address the unsafe condition on these
products.
FAA's Determination
The FAA is issuing this AD because the agency has determined the
unsafe condition described previously is likely to exist or develop in
other products of the same type design.
AD Requirements
For non-radio altimeter tolerant airplanes, this AD requires,
before further flight in Canadian airspace, revising the existing AFM
to incorporate limitations for dispatch or release to airports, and
takeoff, approach, landing, and go-around on runways when operating in
Canadian airspace. This AD provides that modifying the airplane from a
non-radio altimeter tolerant airplane to a radio altimeter tolerant
airplane terminates the AFM operating limitations for that airplane.
While AD 2023-12-14 also specifies limitations for dispatch or
release to airports and takeoff, approach, landing, and go-around on
runways for radio altimeter tolerant airplanes except at 5G Lower C-
Band mitigated airports, this AD has no limitations for radio altimeter
tolerant airplanes. The interference environment at Canadian airports
after July 1, 2026, will be mitigated enough such that those
limitations are not necessary for radio altimeter tolerant airplanes.
The FAA also notes that most Model 747-100, -100B, -100B SUD, -200B, -
200C, -200F, -300, -400, -400D, and -400F series radio altimeter
tolerant airplanes are not subject to the limitations in AD 2023-12-14
under the provisions of an FAA-approved AMOC.
An airplane that is a radio altimeter tolerant airplane using a
method approved by the FAA for AD 2023-12-14 is also a radio altimeter
tolerant airplane for the purposes of paragraph (g)(1) of this AD.
Alternative methods of compliance (AMOC) listed in paragraph (j)(3) of
this AD are approved for this AD.
Differences From Transport Canada AD CF-2024-14
Transport Canada AD CF-2024-14 specifies the fundamental emissions
are in the 3.45-3.98 GHz frequency band, while this AD specifies the
3.7-3.98 GHz frequency band. AD 2023-10-02 and AD 2023-12-14 identified
an unsafe condition from wireless broadband transmissions in the 3.7-
3.98 GHz frequency band, and this AD is based on that same
determination. In addition, an airplane determined to be a radio
altimeter tolerant airplane for the purposes of AD 2023-12-14, which
has demonstrated the performance tolerances for fundamental emissions
within the 3.7-3.98 GHz frequency
[[Page 39455]]
band, would also be a radio altimeter tolerant airplane for purposes of
this AD. Frequencies less than 3.7 GHz are further away from the
frequency bands used by radio altimeters (4.2-4.4 GHz), so an airplane
determined to be tolerant in the range of 3.7-3.98 GHz is also tolerant
to emissions less than 3.7 GHz.
Interim Action
The FAA considers this AD to be an interim action. The FAA may
consider further rulemaking if the Canadian 5G C-Band interference
environment changes or if Canada issues an operational rule to address
5G C-Band interference with radio altimeters.
Justification for Immediate Adoption and Determination of the Effective
Date
Section 553(b) of the Administrative Procedure Act (APA) (5 U.S.C.
551 et seq.) authorizes agencies to dispense with notice and comment
procedures for rules when the agency, for ``good cause,'' finds that
those procedures are ``impracticable, unnecessary, or contrary to the
public interest.'' Under this section, an agency, upon finding good
cause, may issue a final rule without providing notice and seeking
comment prior to issuance. Further, section 553(d) of the APA
authorizes agencies to make rules effective in less than thirty days,
upon a finding of good cause.
An unsafe condition exists that requires the immediate adoption of
this AD without providing an opportunity for public comments prior to
adoption. The FAA has found that the risk to the flying public
justifies forgoing notice and comment prior to adoption of this rule
because radio altimeters cannot be relied upon to perform their
intended function if they experience interference from wireless
broadband operations in the 5G Lower C-Band. This interference can
cause other airplane systems to not properly function, resulting in
increased flightcrew workload, which could lead to reduced ability of
the flightcrew to maintain safe flight and landing of the airplane. The
urgency is based on a change in the 5G Lower C-band environment in
Canada, which is scheduled to occur on July 1, 2026. Accordingly,
notice and opportunity for prior public comment are impracticable and
contrary to the public interest pursuant to 5 U.S.C. 553(b).
In addition, the FAA finds that good cause exists pursuant to 5
U.S.C. 553(d) for making this amendment effective in less than 30 days,
for the same reasons the FAA found good cause to forgo notice and
comment.
Regulatory Flexibility Act
The requirements of the Regulatory Flexibility Act (RFA) do not
apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt
a rule without prior notice and comment. Because the FAA has determined
that it has good cause to adopt this rule without notice and comment,
RFA analysis is not required.
Costs of Compliance
The FAA notes that since operators must comply with this AD before
further flight in Canadian airspace, airplanes that do not operate in
Canada will not have to comply and therefore will have no costs under
this AD.
The FAA estimates that this AD affects 114 airplanes of U.S.
registry. The FAA expects that many of the affected airplanes have
upgraded radio altimeters; therefore, the FAA estimates the total
number of airplanes affected by this AD to be less than the total fleet
size provided in this AD. The FAA estimates the following costs to
comply with this AD:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
AFM revision for non-RAT airplanes 1 work-hour x $85 per $0 $85 Up to $9,690.
hour = $85.
----------------------------------------------------------------------------------------------------------------
Estimated Costs for Optional Actions
----------------------------------------------------------------------------------------------------------------
Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
Modification (radio altimeter ....................... ....................... Up to $120,000
replacement option). (includes parts and
labor).
Modification (filter addition option) 24 work-hours x $85 per $12,000 per filter..... Up to $14,040 (includes
hour = $2,040 per parts and labor).
filter.
----------------------------------------------------------------------------------------------------------------
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. 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 FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: General requirements.
Under that section, Congress charges the FAA 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. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect 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.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866, and
(2) Will not affect intrastate aviation in Alaska.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
The Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:
[[Page 39456]]
PART 39--AIRWORTHINESS DIRECTIVES
0
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
2026-13-14 The Boeing Company: Amendment 39-23397; Docket No. FAA-
2026-7205; Project Identifier AD-2026-00549-T.
(a) Effective Date
This airworthiness directive (AD) is effective July 1, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to all The Boeing Company Model 747-100, -100B, -
100B SUD, -200B, -200C, -200F, -300, -400, -400D, and -400F series
airplanes, certificated in any category.
(d) Subject
Air Transport Association (ATA) of America Code 34, Navigation.
(e) Unsafe Condition
This AD was prompted by the determination that radio altimeters
cannot be relied upon to perform their intended function if they
experience interference from wireless broadband operations in the 3.7-
3.98 GHz frequency band (5G Lower C-Band) when operating in Canadian
airspace, and the determination that during takeoff, approach,
landings, and go-arounds, as a result of this interference, certain
airplane systems may not properly function, resulting in increased
flightcrew workload while on approach with the flight director,
autothrottle, or autopilot engaged. The FAA is issuing this AD to
address 5G Lower C-Band interference that could result in increased
flightcrew workload and could lead to reduced ability of the flightcrew
to maintain safe flight and landing of the airplane.
(f) Compliance
Comply with this AD within the compliance times specified, unless
already done.
(g) Definitions
(1) For purposes of this AD, a ``radio altimeter tolerant
airplane'' is one for which the radio altimeter, as installed,
demonstrates the tolerances specified in paragraphs (g)(1)(i) and (ii)
of this AD, using a method approved by the FAA. No actions are required
by this AD for radio altimeter tolerant airplanes.
(i) Tolerance to radio altimeter interference, for the fundamental
emissions (3.7-3.98 GHz), at or above the power spectral density (PSD)
curve threshold specified in figure 1 to paragraph (g)(1)(i) of this
AD.
[GRAPHIC] [TIFF OMITTED] TR30JN26.003
(ii) Tolerance to radio altimeter interference, for the spurious
emissions (4.2-4.4 GHz), at or above the PSD curve threshold specified
in figure 2 to paragraph (g)(1)(ii) of this AD.
[[Page 39457]]
[GRAPHIC] [TIFF OMITTED] TR30JN26.004
(2) For purposes of this AD, a ``non-radio altimeter tolerant
airplane'' is one for which the radio altimeter, as installed, does not
demonstrate the tolerances specified in paragraphs (g)(1)(i) and (ii)
of this AD.
(h) Airplane Flight Manual (AFM) Revision
For non-radio altimeter tolerant airplanes: Before further flight
in Canadian airspace, do the actions specified in paragraphs (h)(1) and
(2) of this AD.
(1) Revise the Limitations Section of the existing AFM to include
the information specified in figure 3 to paragraph (h)(1) of this AD.
This may be done by inserting a copy of figure 3 to paragraph (h)(1) of
this AD into the existing AFM.
[[Page 39458]]
[GRAPHIC] [TIFF OMITTED] TR30JN26.005
(2) Revise the Operating Procedures Section of the existing AFM to
include the information specified in figure 4 to paragraph (h)(2) of
this AD. This may be done by inserting a copy of figure 4 to paragraph
(h)(2) of this AD into the existing AFM. An AFM with an Operating
Procedures Section that complies with paragraph (h)(2) of AD 2023-12-
14, Amendment 39-22472 (88 FR 40003, June 21, 2023) is acceptable for
compliance with the requirements of this paragraph of this AD.
[GRAPHIC] [TIFF OMITTED] TR30JN26.006
(i) Terminating Action for AFM Revision
(1) Modifying the airplane from a non-radio altimeter tolerant
airplane to a radio altimeter tolerant airplane terminates the
limitations in paragraph (h)(1) of this AD and the operating procedures
in paragraph (h)(2) of this AD for that airplane.
(2) After modifying the airplane to a radio altimeter tolerant
airplane, the limitations in paragraph (h)(1) of this AD and the
operating procedures in paragraph (h)(2) of this AD may be removed from
the AFM.
(j) Alternative Methods of Compliance (AMOCs)
(1) The Manager, AIR-520, Continued Operational Safety Branch, FAA,
has the
[[Page 39459]]
authority to approve AMOCs for this AD, if requested using the
procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send
your request to your principal inspector or responsible Flight
Standards Office, as appropriate. If sending information directly to
the manager of AIR-520, Continued Operational Safety Branch, send it to
the attention of the person identified in paragraph (k) of this AD and
email to: [email protected].
(2) Before using any approved AMOC, notify your appropriate
principal inspector, or lacking a principal inspector, the manager of
the responsible Flight Standards Office.
(3) The following AMOCs approved previously for AD 2023-12-14,
Amendment 39-22472 (88 FR 40003, June 21, 2023) are approved as AMOCs
for paragraph (g)(1) of this AD: FAA AMOC letters 720-23-00133, 720-23-
00137, 720-23-00138, and 720-23-00169.
(k) Additional Information
For more information about this AD, contact Ken Fairhurst,
Continued Operational Safety Technical Advisor, FAA, 2200 South 216th
St., Des Moines, WA 98198; phone: 817-222-5390; email:
[email protected].
(l) Material Incorporated by Reference
None.
Issued on June 25, 2026.
Brian Knaup,
Acting Deputy Director, Integrated Certificate Management Division,
Aircraft Certification Service.
[FR Doc. 2026-13207 Filed 6-26-26; 4:15 pm]
BILLING CODE 4910-13-P
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