AmateurRadio.com

Unpacking the FAA's Boeing 787 Transponder Directive

As SARC Communicator editor I read a lot of blogs, club websites and other sources of amateur radio news. This one particularly caught my eye.

The source

https://www.paddleyourownkanoo.com/2026/03/14/ham-radio-enthusiasts-land-u-s-airlines-with-8-million-bill-to-fix-faulty-equipment-on-boeing-787s/ 

The ‘click-bait’ headline:

Ham Radio Enthusiasts Land US Airlines With 8 Million Bill To Fix Faulty Equipment On Boeing 787s

Ham radio enthusiasts could be partly responsible for landing U.S. airlines with an $8 million bill to fix faulty equipment on Boeing 787 Dreamliner airplanes after it was discovered that simple radio signals can knock out a faulty transponder on the popular widebody plane used by American, United, and Alaska Airlines.

The issue came to light after the Federal Aviation Administration (FAA) reported “multiple instances of loss of transponder for airplanes entering airspace in the presence of CW interference.”

CW interference refers to continuous-wave radio signals like Morse code, military transmitters, and even amateur ham radio signals, which could interfere with the transponder on some Boeing 787s...

When I saw this story it didn’t seem to add up. After all, Amateurs have been sending CW for a century and there has never been an allegation such as this. Although my own and other readers’ feedback has resulted in an adjustment of the original deceptive headline, the underlying story deserved  further investigation.

The actual facts

When the FAA warns of "CW interference," hams think of Morse code. Aviation engineers think of something far more dangerous—a silent, invisible wall of noise that can blind a Dreamliner to oncoming traffic.

In the world of amateur radio, "CW" is a beloved mode—the rhythmic cadence of Morse code cutting through the static, a testament to communication's simplest form. But when the Federal Aviation Administration (FAA) uses the same two-letter abbreviation in an airworthiness directive, it is describing something far more insidious and utterly unrelated to the operator in the shack.

For an avionics engineer, "Continuous Wave (CW) interference" refers to a pure, unmodulated, single-frequency carrier signal that has no business being where it is. It is a rogue tone, a sustained note of radio energy that can overwhelm sensitive aircraft receivers. And according to a new Notice of Proposed Rulemaking (NPRM) from the FAA, this type of interference is posing a direct threat to the Boeing 787 Dreamliner's ability to see and be seen by other aircraft.

The proposed directive, https://www.federalregister.gov/documents/2025/06/13/2025-10759/airworthiness-directives-the-boeing-company-airplanes which would affect 150 U.S.-registered 787-8, -9, and -10 aircraft, mandates a costly hardware replacement to fix a vulnerability that could, quite literally, render an aircraft invisible in busy airspace. But what exactly is this interference, and why is a simple hardware swap estimated to cost U.S. operators nearly $8 million?

The Problem: A Transponder That Won't Talk Back

At the heart of the issue is the 787's Integrated Surveillance System Processor Unit (ISSPU), a critical component that manages the aircraft's transponder. The transponder's job is to listen for interrogations from Air Traffic Control radar and other aircraft's Traffic Alert and Collision Avoidance Systems (TCAS) on 1030 MHz, and reply on 1090 MHz. Note that this is far from the usual HF frequencies that Amateurs normally operate at.

According to the FAA directive (Docket No. FAA-2025-0924), multiple reports have surfaced of 787s entering airspace with active "CW interference" and suffering a specific, dangerous failure: the transponder stops meeting its Minimum Operational Performance Standards (MOPS). Instead of correctly replying to at least 90% of interrogations, the unit becomes desensitized, failing to respond.

This is not a gradual degradation. It is an "unannunciated" loss, meaning the pilots receive no warning light, no aural alert, no indication that their aircraft is no longer replying to ground radar or TCAS inquiries. The first sign of trouble could be a gap in the sky where an airliner used to be, visible to everyone except the pilots of the aircraft that just went silent.

"CW" for the Layman: Not Morse Code, But a Wall of Noise

This is where clarification for the broader technical community is essential. For the amateur radio operator, "CW" (Continuous Wave) is synonymous with Morse code—a carrier wave that is turned on and off to form characters. It is intermittent, intentional, and communicative.

The "CW interference" cited by the FAA is something else entirely. In engineering terms, a "continuous wave" simply means a steady, unmodulated carrier signal. Think of it less as a conversation and more as a sustained, single-frequency tone—a pure, unbroken note of radio energy. If a pulsed radar signal is like a strobe light, CW interference is a laser pointer held steadily on a sensor, blinding it.

For a transponder receiver trying to pick out weak interrogation pulses from the sky, a powerful CW signal on or near its operating frequency (1030 or 1090 MHz) acts as a "jammer." It raises the noise floor, drowning out the very signals it needs to hear.

The Hunt for the Source: Who Is Generating This Noise?

The FAA directive is notably silent on the source of this interference, focusing instead on fixing the aircraft's vulnerability to it. So, who or what is generating these rogue continuous wave signals? The answer is complex and points to a crowded, modern radio spectrum. While the public document does not specify frequencies, the affected systems point squarely at the 1030/1090 MHz bands. Likely culprits for high-power CW interference in or near these frequencies include:

• Ground-Based Military and Civilian Radars: Some radar systems, particularly those used for long-range surveillance or specific military applications, can produce strong continuous or quasi-continuous output that generates harmonics or spurious emissions.
  
  
• High-Power Data Links: Terrestrial microwave data links, used for point-to-point communication by telecom companies and utilities, operate in frequency bands that can, with faulty equipment, generate out-of-band emissions that bleed into the aviation surveillance bands.
  
  
• The 5G Debate, Revisited: The recent spectrum battles between aviation and 5G carriers centered on the potential for signals from powerful ground-based transmitters to cause interference with radar altimeters. While that specific fight involved different frequencies (3.7-3.98 GHz), it perfectly illustrates the principle: a powerful, continuous transmission on a nearby frequency can overwhelm aircraft receivers if filtering and shielding are insufficient.

The $7.95 Million Fix

Because the sources of interference are myriad and largely outside an airframer's control, Boeing and the FAA have chosen to harden the aircraft itself. The proposed solution is not a software tweak, but a physical replacement of the vulnerable hardware.

While then issue is a worldwide problem, the directive would require US based operators to replace the left and right ISSPU units, swapping out current part numbers (822-2120-101 and -102) with a new, presumably better-shielded or more selective unit (part number 822-2120-113) . 

The FAA estimates the parts alone will cost $52,661 per aircraft. With labor, each of the 150 affected U.S. planes will incur a $53,001 expense, bringing the total for U.S. carriers to $7,950,150 .

This is a significant investment for a problem that many in the industry suspect is not going away. As the radio spectrum grows ever more congested with diverse signals, the threat of "CW interference"—in its true engineering sense—will only increase. For the pilots of the Dreamliner, this hardware upgrade can't come soon enough. For the amateur radio operator tuning up on 40 meters, rest assured: your key is not the culprit. The real threat is coming from elsewhere in the increasingly noisy radio spectrum we all share.

73,

~John VE7TI

There’s been a festering, ongoing social media battle over Hamvention, its new venue, the fairground in Xenia, and the old Hara arena.  It seems this has bubbled up to the surface again with the recent tornado disaster in Trotwood which severely damaged homes and the venerable, but severely dilapidated Hara Arena.

I won’t dispute that Hara was a dump.  It was a major dump.  It was abused over the years and its long tenuous financial history is available for anyone who wants to find it on the interwebs.  Despite being a dump, Hara was an ideal venue for the Hamvention.  Hamvention started there, grew with Hara even through its physical decline, and the legendary event arguably was molded and enabled by the capabilities the site offered.  Hara may be rebuilt and Hamvention may or may not return to Hara, but I’m not going to bet on it or even entertain the thought.

What bothers me is that some dismiss any commentary or criticism of the Xenia location as merely Hara Arena fanatics sore over the loss of Hara, or simply as complainers.  That’s not the case.  I’ll acknowledge that Xenia was likely the best choice out of a few choices at the time, but it’s just not well suited long term for the Hamvention.   There’s a lack of major highways and hotels nearby. The mud pit parking has become legendary.  The buildings are more suited to host livestock than technology.  The flea market is in the grassy track center, because, well, there’s no where else to put it.  And last, the venue doesn’t feel like the largest amateur radio gathering in the western hemisphere.  It feels like a county fair with amateur radio.

It’s not realistic to think Hamvention will return to Hara anytime soon.  I think what many of us would like to see is a realization that Xenia isn’t an ideal location, and it has changed the character of the event.  Xenia was a prudent, stopgap measure taken under difficult circumstances.  Now that the immediate threat to the future of the event has passed, the Hamvention powers that be should seek a better venue for Hamvention and not settle for Xenia.

This article originally appeared on Radio Artisan.

In the past I’ve been a strong proponent of ARRL.  I often mentally tied the past and future success or failure of amateur radio to the organization.  I’ve come to the conclusion that this just isn’t the case, and in my evolving opinion the organization is becoming less relevant as time goes on.  The elected leadership hierarchy to me seems archaic.  I tend to doubt the slate of new blood “change” candidates which got elected will change much, as long as the majority of ARRL leadership, and to some extent the general population of amateurs in the US, continues to have the demographic makeup that it does.  My life membership has essentially become a good deal on a perpetual magazine subscription, assuming that I don’t get hit by a bus anytime soon.  I’m convinced it’s non-centralized grass roots efforts from individuals that are going to make or break amateur radio in the coming decades.

So, one of my 2019 “amateur radio resolutions” is to stop worrying and pontificating about ARRL, and be that individual that leads my own grass root effort.

I have my opinion on ARRL asking FCC to grant more HF privileges to Technician-class licensees.

I verbalize them in this video:

[embedyt]https://www.youtube.com/watch?v=BWSAvDWE3Js[/embedyt]

After you hear my comments, please leave your comments.

Thanks, 73 de NW7US dit dit

The following open letter to the ARRL Board of Directors and Leadership is in concert with many others coming from current members in response to the activities occurring at the ARRL Leadership level.

To join in and voice your thoughts, please visit:

(More information is found after the following open letter)

To: All ARRL Directors and Officers

From: NW7US

Many actions–policy and governance–taken by the League’s leadership over the past two years trouble me. Formalization of specific actions planned for the Board meeting on January 19, 2018, specifically worries me.

At this time, any action taken by the ARRL Board of Directors cause me concern. As a result of this, I add my name to those seeking that the Board delay consideration of any ByLaw changes at the January 19 Board meeting.

In particular, I strongly urge you to:

1. Reject any proposal to allow the President and individual Vice-Presidents to vote as Directors.

2. Reject any provision that allows expulsion of an ARRL member “for cause” without delineated criteria.

3. Reject any provision that allows expulsion of any Director, Vice-Director of Officer for bringing ARRL into “disrepute” without specific criteria.

4. Reject any provision that reduces Members’ ability to recall a sitting Director.

5. Reject any current or proposed provision that allows the Board to disqualify candidates for elected office without full disclosure of the reasons for such disqualification.

6. Reject any proposal that would allow the Board to designate replacements for Directors instead of appointing an elected Vice Director or other elective processes.

7. Reject any current or proposed provision that allows censure, removal or other disciplines of a Director for revealing or openly discussing any view expressed at a Board meeting that is not consistent with the Board’s action.

8. Adopt a policy that elected Directors, and Vice Directors are not “personnel” for the purposes of declaring that any information about removal or disqualification is confidential and may not be released.

It is crucial that ARRL remain a solidly democratic, membership-based organization with principles of openness and accessibility through our elected Directors. I urge you to vote per my wishes at the January 19 meeting.

Beyond these issues of governance, I am concerned about the policy-making process of the ARRL leadership–leadership that I feel has become much less Member-driven, and that no longer reflects the needs of the Membership.

Ham radio is in a time of transition. The ARRL must focus on the issues that make a difference for the future success of the hobby.

73, Tomas Hood / NW7US

More information about this effort:

myARRLvoice is an independent grassroots group of amateur radio operators working on behalf of our fellow Members of the American Radio Relay League (ARRL), monitoring the activity of its leadership and advocating change to optimize the organization’s effectiveness in matters of policy and governance, and to foster ethical and competent stewardship.

myARRLvoice acts as a vehicle for ARRL Members to make their voices heard on matters of governance and policy, and to participate in the policy-setting process, holding our elected and appointed leaders accountable. We strive to make the activities of ARRL leadership more transparent by insisting on the creation and dissemination of records of the deliberations and actions of all ARRL Boards, Committees, and the operational Executive Team.

myARRLvoice believes that good ARRL stewardship can only be achieved through a check and balance system that includes the watchful eye of the Membership.

Visit the website at www.myarrlvoice.org

For the first time in my amateur radio career, I’m beginning to look upon ARRL unfavorably.  About 15 years ago after I acquired a lifetime subscription, my grandfather chastised me saying I’d eventually grow tired of the League and would regret my subscription.  I’m sad to say I think that day may have come.

Over the years I’ve defended ARRL, in both in person conversations and online.  ARRL attracts a lot of haters, often unfairly, for wrong reasons.  For example, I’ve witnessed many hams hate ARRL, claiming they don’t like CW and worked to eliminate it, despite ARRL supporting code testing for Extra licensing in their FCC comments filings years ago, and offering daily code bulletins and practice over the air.  Despite ARRL’s faults and shortcomings, amateur radio would not be where it is today, and perhaps not even exist, if it wasn’t for ARRL.

With the recent Code of Conduct and censure incident and the proposed voting and membership changes, I’m left with the impression of an organization that is closed, secretive, adverse to dissent, and focused on self-preservation.  The Force of 50 debacle points to an organization eager to project to the public a disaster response “photo-op” image that neither the organization or the amateur radio service supports or deserves.  Over the years I’ve personally seen other examples that support these two impressions but never dwelled on them as ARRL garnered my utmost respect as I felt that the League, despite its flaws, in general was taking amateur radio in the right direction.  I no longer have that confidence in the organization.

While I could end my diatribe with the paragraph above, I really want to explore or ask, what is the solution to “fixing” ARRL?  ARRL does a great job with publications and education, contesting, and lobbying the FCC.  Does the large and seemingly complicated hierarchal governance structure really serve a purpose today?  It appears that structure is geared more towards emergency communications initiatives than an effective membership feedback vehicle or advancing the radio art.  Is this structure the problem and ARRL needs to be transformed into more of a flat, responsive, grass-roots kind of organization?

This article was originally published at Radio Artisan.

Some of you wanted to see the complete version, uncut, of this video in which I discuss the differences between CB and the Amateur Radio Service.  This is in response to the recent episode in which the NCIS writers missed a great opportunity to discover the vibrant reality of the current amateur radio service in the United States of America.

The previous version of the video was prematurely cut short by just over three minutes.  This version includes that ending.  I also remove some of the low-end rumblings from the vehicle.  This version should sound a little bit less annoying.  Hopefully, the quality of the video is sharper, as well.  This version was edited by Adobe Premiere CC 2017.

I appreciate the many comments, views, and shares.  Please subscribe, too!

73 from Omaha!