Recently telecom companies AT&T and Verizon have decided to ‘temporarily limit their new 5G network within two miles of airports‘. In the prior weeks before this decision, hundreds of flights had been canceled and the airlines were in the process of implementing more mass flight cancellations of passenger and cargo flights if the telecoms companies didn’t cease installation of 5G near airports.
Airlines have been concerned that new 5G services ‘could interfere with some radio altimeters, devices that, among other things, determine a plane’s altitude, posing a safety risk especially in bad weather.’
What is an altimeter?
An altimeter is a device that measures altitude—a location’s distance above sea level. Most altimeters found in aircraft are barometric (commonly known as pressure altimeters), meaning they measure altitude by calculating the location’s air pressure, however some planes use radio/radar altimeters. Old data suggests that ‘at least 25,000 aircraft in the US have at least one radio altimeter’.
The potential interference 5G could have on radio altimeters is the biggest concern for airlines. ‘C-band frequencies used by 5G are closer to the portion of airwaves used by the altimeters than the frequencies used by earlier generations of cellular service’. In simple layman terms 5G technology is competing on almost the same frequencies that some airplane radio altimeters use.
What would happen if interference occurred?
Peter Lemme, a former Boeing engineer of 16 years, gives this chilling warning. ‘If an altimeter’s waves don’t bounce back because of 5G interference, or can’t be distinguished from other nearby waves, the altimeter could give the wrong reading or not function at all’ A malfunctioning altimeter could fail to warn pilots and plane computer systems of real threats and even pick up phantom obstacles.
Airlines are right to be concerned about potential interference from a new telecoms technology. 5G would not be the first time that a new mobile phone technology has adversely affected other technologies. In Brookings article ‘Will 5G mean airplanes falling from the sky?’ Tom Wheeler Chairman of the Federal Communication Commission (FCC) from 2013 to 2017 wrote ‘When digital mobile phone technology was first introduced in the US, electric wheelchairs began behaving erratically.
When phones using GSM digital standards were first introduced hearing aids would buzz. He also highlighted the previous dangers of cell phone signal interference with pacemakers. However, when it comes to risk of planes being affected by 5G, Mr Wheeler says that F.C.C. engineers had found no real cause for concern.
Experts in the airline industry on 5G around airports
Experts in the airline industry don’t share Mr Wheeler’s confidence in 5G, they are most worried about 5G interference with altimeters on Boeing 787s, a large plane that is typically used on long, international flights. Altimeters are a key part of the 787’s landing system that turn on reverse thrusters to slow the plane once it has landed.
Mr. Lemme an expert who is knowledgeable in Boeing patents, suggests that landing functions which link to information from the altimeter are automated.
A pilot would not be able to reverse a 787 thrusters if the altimeter malfunctioned.
Mr. Lemme has said. “You absolutely could have some planes running through runways”
Stephen Gandel, editor for the New York Times writes ‘telecommunications experts say that there is little or no risk to altimeters from 5G and that the aviation business has had years to prepare for what little risk there is.
Perhaps the best expert to listen to on the matter is Seth Frick, a radar system engineer at Honeywell Aerospace (which makes altimeters for many aircraft, including its own military helicopters).
Mr Frick spoke as a panellist at a webinar recently held by The Helicopter Association International for its members on 5G interference. Mr. Frick said Honeywell when testing 5G interference had found a range of errors, from altimeters “getting noisy” to providing no reading. Furthermore he went on to say “I don’t know if there’s any cases where we can say there is absolutely no interference”
It is ironic that the dispute is between the airlines and AT&T, as the altimeter was patented by inventor Lloyd Espnchied who spent more than 40 years working for Bell Labs, a research arm of AT&T.
What happens now?
The jury is out on the risk of 5G to airlines, but would you prefer to believe the opinions of advocates of the telecom industry or the opinions of safety experts in aviation who have actually run tests of aviation equipment around 5G.