FAA Warns 787s Especially Susceptible To 5G


The FAA is warning Boeing 787 operators that 5G interference “could prevent engine and braking systems from transitioning to landing mode, which could prevent an aircraft from stopping on the runway” when the runway surface is wet or contaminated. In an Airworthiness Notification issued Jan. 14, the agency says information from Boeing says “anomalies” in the 787 systems mean 5G interference with its radar altimeter can affect a host of systems, including those that allow the operation of controls that are only used when the plane is firmly on the runway.

“As a result, lack of thrust reverser and speedbrake deployment and increased idle thrust may occur; and brakes may be the only means to slow the airplane,” the FAA said in the notification. “Therefore, the presence of 5G C-Band interference can result in degraded deceleration performance, increased landing distance, and runway excursion.” The notification affects all 1,010 aircraft in service for almost 100 operators worldwide and includes 137 aircraft registered in the U.S.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.

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  1. Well, ya know, people want to watch “My MTV” on their phones wherever they may be. C’mon, what’s more important in the moment? The possibility of missing some twit on Tik Tok or crashing a 787?

    • Listen to some RF comm types and you’d wonder – such as the twit supposed expert who wrote in USA Today.

      (Another newspaper that lacks editors.)

  2. Okay.
    Why would you design any system that uses radar altimetry information to determine a weight-on-wheels condition?
    I’m beginning to wonder whether a lobotomy is a requirement for obtaining a design engineering position at Boeing. And elsewhere.

    • Boeing saved a few bucks on the B787 radar altimetry system. Saved even more by not testing the system for frequency interference.

      To get an engineering position there one needs to have an “in” with the FAA.

      • The approval for cellphone operators to use the frequencies next to the radar altimeter band was proposed 2 years ago. Numerous studies showed potential interference. But the FCC sold the frequencies anyway. It’s called the power of money. Other countries have limited C band power, limited antenna angles, and limited deployment near airports. But the US has not.

        This is not Boeing’s fault. It is the FCC’s.



        • Vince:

          I agree with your assertion that this 5G fiasco “is not Boeing’s fault.”

          But the point that I was making is that designing a system that relies upon radar altimetry information, to make a weight-on-wheels determination, is… poor engineering judgement. It is CONCEPTUALLY flawed.

          And as I’ve often repeated in this space, “The very best implementation of a flawed concept is, itself, fatally flawed.”

          This consequent 787 problem very much IS Boeing’s fault. And it appears to be another example of a PATTERN of generational engineering incompetence, these days.

    • Most modern airliners synthesize air/ground determination from multiple sensors such as airspeed, groundspeed, squat switches on each bogie, vertical rate, and so on. Most will include radar altimetry as part of the mix. The objective is to be fault-tolerant so that loss of one input still comes up with the correct answer for all flight regimes. The weakness that is implied here may only be that the RadAlt is given too high a priority in the 787 air/ground system compared to the other inputs.

    • Likely because the old method of switches on landing gear scissors, either mechanical or proximity sensing, has been troublesome and requires a cable down the landing gear which is a maintenance cost. (Out in the SWAMP with things hitting it.)

      Knowledge is good, flapping bad.

  3. I retired from Lockheed. Working mostly on the L-1011 program. Used to have tremendous respect for Boeing. What in the hell has happened to them? Sad.

    • Killed by the greedy business people running the company. Engineering companies should be controlled by boards with at least 50% engineering people who actually understand the ramifications of decisions made.

  4. It’s bad enough that Boeing is “designing” fallacious systems, the FAA — itself — is complicit. We here all lament how long it takes to certify something new or controversial for GA yet it almost appears that if you’re a large manufacturer, you can just do it and some internal person or group waves their magic ‘twanger’ and … blam … it’s certified. As Yars says, who the hell is working at Boeing these days?

    • How are modern radar altimeters in 787s susceptible to interference from bands that they don’t use? Shouldn’t these products have been designed from the start under the assumption that adjacent bands would eventually be used?

      • Read up.

        Designing circuity for aircraft jobs is tricky, unless you want boat weight.

        Perhaps shortsighted choices, not new – read up on bunfight from several years ago over ILS and the outfit with grand satellite schemes that veered off into using far more ground stations than it promised to get spectrum licenses.

        Good that detail work is being done, one news report says FAA has cleared 45% of airliner fleet so far.

  5. A daughter was smart enough to ask someone she thought might know about the subject – me, instead of guessing like flappers herein.

    Do any of them have pilot licenses, if so why did they qualify?

  6. Although a radar alt is useful, when shooting an ILS, we always use the barometric alt for the approach & to minimums – never looked at the other gage.
    I always thought it would be useful if the regular alt goes inop.
    My take

    • Having made sure you set baro correctly and are in tune with the procedure your airline specifies (should you be reading zero at touchdown, or field elevation?).

      Plus anti-icing on (which may include static ports).

      Cross-checking is good practice.

      We thought a radalt might have saved the Pacific Western B707-320C that should have been 400 feet above the gravel pit near Leduc Alberta on night approach to YEG, but wasn’t. Fatal for crew and load of cows.

      (Reading the accident report for the first time, it seems crew were distracted by something – perhaps electrical system, and let the airplane drift down until it hit trees.j
      Perhaps the alert light on the radalt would have helped, if set to an appropriate altitude. FE might see that and general situation, but if there was a systems problem he’d have been working that.)

      [Radalt was not standard on 707s in those days, the replacement airplane sure did along with Collins FD and 737 approach progress displays. Those are slick, dark-amber-green progression coming down the glide path.]

  7. Read the later AvWeb thread ‘Another Tuesday another 5G…’ for lead to FAA information pages and other knowledge.