How are U.S. airlines doing, in upgrading their aircraft to make sure they’re safe from 5G interference? They are getting there, it seems.

It’s been a while since telecom providers got the all-clear to switch on (or turn up) their 5G transmitters near airports. If you missed it, this happened on the 1st of July this year. Several weeks earlier, U.S. Secretary of Transportation Pete Buttigieg warned the airlines that the arrival of the deadline presented “a real risk of delays or cancellations”.

Thankfully, few if any airlines reported disruptions to their aircraft operations due to 5G interference. Of course, weather was a factor. The reason the mid-summer deadline was chosen was because the effects of 5G interference on aircraft systems would be greater in low visibility and/or operations on wet runways.

This is because 5G C-band signals are very close to the range used by radio altimeters. Airliners increasingly rely on radio altimeters not only to read their distance from the ground but also as a way to verify that the aircraft is ON the ground. This is important, as a faulty system could delay the activation of systems, like the ground spoilers and/or brakes.

5G, Radio Altimeters, and Aircraft Maintenance

When the July 1st deadline came and went, around 20% of the U.S. airline fleet lacked new 5G-resistant radio altimeters. It’s worth mentioning that many (most?) aircraft radio altimeters had the necessary filters to handle 5G interference, even before this crisis.

This seems to be because the manufacturers of these devices followed industry standards for interference even though aviation authorities didn’t call for them. Even so, the chance of disruptions remained. And the odds for disruptions grow as the summer gives way to autumn.

Or do they? Well, airlines in the U.S. continued to update their aircraft with 5 G-resistant altimeters, all through the summer. According to Reuters, Delta Airlines says that all of its in-service airliners now have 5G-compliant altimeters.

This includes Delta’s regional aircraft.  The airline still has some aircraft that lack 5 G-resistant altimeters. But these jets are undergoing maintenance. They should get their new altimeters before re-entering service.

This means that Delta added 5G-compliant altimeters to 190 airliners in around two months – minus those jets undergoing maintenance. Delta increasingly relies on its Airbus A220 fleet for many of its domestic flights. All of these relatively new jets had non-compliant altimeters on July 1st.

It is not clear how far behind (or ahead) other U.S. carriers are, in changing their radio altimeters. Of course, foreign carriers flying to and from the United States also need such altimeters. This may be easier for them to organize, as it doesn’t necessarily involve all of their fleets. However, it could still require operating a different aircraft type than what these carriers would prefer to operate.

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