FAA Says Some Radar Altimeters Need Replacing


Reuters is reporting the FAA met with airlines and cellular service providers last Wednesday to plan the eventual replacement of the 10 percent of radar altimeters considered susceptible to interference from 5G C-Band signals. The news agency got a look at a letter to those invited to the meeting and the agency isn’t interested in hearing any other opinions on the topic. Reuters quoted the letter as saying the purpose of the meeting was to set “an achievable timeframe to retrofit/replace radar altimeters in the U.S. fleet.” It further directed aviation representatives “to offer options and commit to actions necessary to meet these objectives.”

In the frenzy that followed the fractured rollout of 5G in January, the FAA quickly cleared about 90 percent of the fleet for operations where 5G is available, but the remainder are restricted in the types of instrument landings they can do. As an interim measure, some of the altimeters might be fitted with filters that can suppress the interference, but the agency seems determined to get rid of the offending equipment. There was no mention of who will be paying for the new equipment but it’s bound to come up. It’s also unclear what will happen after the July 6 deadline set by the telecoms to end the restricted operation of 5G near 50 airports that was part of a deal struck with them by the FAA in January. Last week Transportation Secretary Pete Buttigieg said issues with 5G would linger for years.

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  1. On the matter of who pays for this, especially since the FAA is not interested in any suggestions, I’ll bet the FAA will use this as a way to further thin out older planes that may just barely meet stage 3 noise limits, or RVSM. I’m sure those airplane owners will get stuck paying for this. Chances are the cost of replacing an older radar altimeter unit will again exceed the value of the older planes involved.

  2. The FAA & the FCC are proxies for the airlines & the wireless providers in the battles for use of a very crowded, but finite spectrum. As you can see on the chart below, aviation is not the only player. In fact, we flyers are spectrum hogs with our fat, inefficient legacy AM signals everywhere (check the chart).

    Older radar altimeters had sloppy signal filtering because there was no competition for those frequencies when they were built. Today, that spectrum is hot public property used by dozens of radio services, all legitimate users.

    Like our other spectrum hog brothers, the AM & TV broadcast stations, we flyers will eventually be switched to FM, digital communications. Spectrum is a terrible thing to waste.


  3. Mandated replacement of obsolescent avionics is certainly nothing new; old timers recall having to replace comm radios that didn’t meet the frequency tolerances needed to co-exist with tighter channel spacing. The aircraft owner/operator paid, and life went on.