FAA Shows ‘Sample NOTAMs’ For Possible 5G Restrictions

14

The FAA has prepared samples of the NOTAMs it may start issuing starting Jan. 5 when 5G broadband service begins in 46 cities. If the NOTAMs are issued, they would drastically affect operations of airlines, commuter airlines and many charter and business aircraft. In a statement issued Dec. 23, the agency said it will disallow the use of many instrument approaches and any aircraft systems that rely on radar altimeter data including autoland, head-up displays and enhanced vision systems “where 5G interference is possible.” 

In the statement, the agency says it’s working with the FCC and telecom operators to allow the systems to safely coexist but until that process is complete it’s ready to start restricting operations if it thinks there’s a chance that radar altimeter can be rendered unreliable by 5G. Below is a sample NOTAM of the type that could be issued covering any or all airports the FAA think might be affected by 5G. Again, it’s not a real NOTAM. It’s just a sample of what could be issued when 5G goes live on Jan. 5.

Example Aerodrome NOTAM for airports:

 BDL AD AP RDO ALTIMETER UNREL. AUTOLAND, HUD TO TOUCHDOWN, ENHANCED FLT VISION SYSTEMS TO TOUCHDOWN NOT AUTHORIZED EXC FOR ACFT USING APPROVED ALTERNATIVE METHODS OF COMPLIANCE DUE TO 5G C-BAND INTERFERENCE PLUS SEE AIRWORTHINESS DIRECTIVE 2021-23-12

And below is a sample of a NOTAM covering instrument approaches:

Example IAP NOTAM against impacted approaches (SA CAT I / II, CAT II, III, or RNP AR):BDL IAP BRADLEY INTL, WINDSOR LOCKS, CT. ILS RWY 06 (SA CAT I AND SA CAT II), AMDT 13A… ILS RWY 06 (CAT II AND CAT III), AMDT 38A… RNAV (RNP) Z RWY 06, AMDT 1… RNAV (RNP) Z RWY 24, AMDT 1… PROCEDURE NOT AUTHORIZED EXC FOR ACFT USING APPROVED ALTERNATIVE METHODS OF COMPLIANCE DUE TO 5G C- BAND INTERFERENCE PLUS SEE AIRWORTHINESS DIRECTIVE 2021-23-12

There could also be NOTAMS issued for private airfields with GPS approaches and helicopter operations requiring radar altimeters for hover autopilot modes, search and rescue autopilot modes and heliport instrument approaches. The FAA does say it will allow exemptions for those who have approved alternative methods of compliance but we’re not aware of any exemptions that have been issued. There are concerns that 5G signals, which use 3700-3998 MHz, can overpower radar altimeter signals, which operate in the 4200-4400 MHz band. So far the FCC and the telecoms have maintained that there is no evidence that such interference will occur but the FAA and aviation groups have said there is no proof that it won’t.

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.

Other AVwebflash Articles

14 COMMENTS

    • And if we were still having commercial accidents at the same rate we had in the 90s (not even the 60s), there would be about one major airliner accident per week.

  1. It was *somebody’s* job to see if 5G would affect any other type of communications. There was a period of several years where this could have been worked out.

  2. Richard Phillips, are you new to aviation? 5G interference was widely discussed as a problem for aviation safety. Despite this, the telecom industry (and their lobbyists) prevailed so here we are. The FAA is doing what they have to do to ensure safe flight operations.

    • No need to become offensive.
      The questions is not whether or not it has been discussed before, but whose responsibility it’s been to provide conclusive evidence that the new technology doesn’t mess with existing one (as “no evidence that there is interference” isn’t exactly conclusive).
      I wonder how these fundamental questions were clarified to everyone’s satisfaction when it came to the introduction of onboard internet for passengers..? (Not a suggestive question, I simply don’t know).

  3. Seems weird that there’s a conflict. According to the article:

    “There are concerns that 5G signals, which use 3700-3998 MHz, can overpower radar altimeter signals, which operate in the 4200-4400 MHz band.”

    Those look like they’re quite a few Hz apart – 202 Mhz apart at the closest point. (As a point of reference, the entire air band VHF segment is only 25 MHz wide.) Is the problem that the 5G guys are operating outside of their band, or that the RA receivers have poorly designed filters, or is there some kind of harmonic that overlaps the RA range?

    • Although there doesn’t seem to be much definition of the “theory” behind the narrative being pushed, it seems to revolve around the belief, fear, narrative necessity, or whatever it is that the receiver segment of radar altimeters have, or might have, or could have, such poor rejection of out-of-band signals that any moderately strong signal within – what? – hundreds of megahertz? thousands? – would cause them to display inaccurate readings. Anyway, hypothetically at least, we definitely have, or might have, or could have, a problem.

      In order to mitigate all this uncertainty, a logical course of action would seem to involve finding out what the actual characteristics of the radar altimeters are. Or we can always just continue the battle of the hypotheticals.

    • Unfortunately, as people who have been graced by the magic that is RF on a personal level, from the HAM down the street to the engineer in the lab testing the gear, have learned: just because you want to be transmitting on one set of frequencies doesn’t mean you aren’t also transmitting on a whole host of others. Furthermore, old equipment is not designed with constraints nobody had ever thought of at the time in mind.

      Mass-produced, cheap RF devices are among the worst offenders, and with 5G base stations deployment being estimated in the millions by the time the rollout is “complete” to get good coverage, the only way for this huge infrastructure deployment to remain profitable for the carriers is for the equipment to be cheap and installed quickly. Cheap means likely QC issues, which mean a lot of unwanted emissions (including pop-fly spurious emissions) are likely. Installed quickly means people aren’t going to be going around doing field strength surveys to make sure the antennas aren’t aimed such that they’re bouncing or even emitting something straight up on the final approach to your local airport. While it isn’t likely to be a constant issue that renders your radar altimeter visibly wonky any time you fly over a 5G coverage area, it has been demonstrated by lab testing that there is a good probability that there will interference given the sheer number of interactions and, take this one seriously; the environment the avionics were designed to operate under – was definitely not a world covered in millions of kiloWatt range ERP transmitters broadcasting with massive bandwidth 24/7, 365.

  4. Considering the state of the current NOTAM system, this is going to be one hell of a mess. It won’t effect my company because we don’t do cat ll or rnp approaches. The additional FAA required training to get authorization for those type approaches just is not worth it. For some pt121 airline ops this could be a real issue in locations where weather consistently goes below 200ft and 1/2mi,1800 rvr.

  5. I just started wondering about 5g phones onboard. We all know that passengers don’t necessarily do what they are told. Are 5g signals from the phones’ transceivers strong enough to also interfere with radar altimeters?

  6. Anyone else notice 5g concerns were largely ignored when GA said it might be an issue, but now that carriers are saying something, it’s finally acknowledged? Maybe that’s just my impression. I suppose it’s good to get an ack, but it’s too late to fix, and my new 5G phone … I’m being kind when I say it’s a real POS when it comes to reliability, so it looks to me like we traded one thing that worked for two things that don’t.

  7. Ummmm…. Why?
    If someone has lawfully been using bandwidth and someone else shows up causing a serious danger to the public… who should be shut down? Hint… not the people previously licensed and using the bandwidth without a endangering the lives of others.

    Few times have I ever heard of the FCC doing something so damn stupid with the frequency band than this… a time when it actually endangers lives… yea, frequency misuse is rarely an actual danger to lives. This is worse than jamming ATC frequencies…

  8. In the long run the Radar Altimeter will be replaced with a modern technology. The products that benefit the greater percentage of the population are less expensive. Aviation specific products are always radically more expensive. There’s other technology that provides the pilot with altitude Above Ground Level (AGL) now and most likely more on the way. I’ll bet the Radar Altimeter replacement will be more accurate, cheaper and lighter.

LEAVE A REPLY