In many countries and on most airlines, passengers are reminded to turn their phones’ cellular functionality off before every flight. This requirement alone led tech companies to develop “airplane mode” and name it accordingly. The reasons for cellular devices preflight announcement are straightforward and long-established. This article will talk about the background of the use of airplane mode and how dangerous phones really are. Additionally, the 5G US rollout troubles will be addressed at the end.
Regulatory background
Regulators differ on the topic of whether phones need to be in airplane mode or not. For its part, the FAA in the US disallows the use of cellular devices if they do not have their carrier-provided cellular transmitting function turned off (otherwise known as airplane mode). The FAA outlines this policy in Advisory Circular 91.21-1D, where it’s made clear in section 9.2 that using a personal electronic device’s cellular transmitting functions in the air is a Federal Communications Commission (FCC) rule which the FAA enforces. Passengers are allowed to use cell phones to make calls on the ground according to the Advisory Circular, but airlines must ensure passengers turn this function off in the air.
The European aviation regulator EASA was in agreement with the FAA until September 2014. Since then, EASA has allowed electronic devices to remain on and connected during all phases of flight. In a press release, EASA explicitly states that devices no longer need to be in airplane mode during flight. However, each airline maintains discretion about the application of this rule and can only allow passengers to use devices after an undefined “assessment process.” The bottom line is that there is a decade-old precedent set by EASA which allows for full cell phone use in-flight.
Safety considerations
The argument behind every regulation is safety. In the case of cell phones, the FAA and FCC reason that cell phones can interfere with critical navigational systems on planes. At the top of the list of systems that use radio frequency bands are ILS components used for landing in poor weather, as well as ground-based systems like VORs and other beacons. These nav aids reside at the lower end of the electromagnetic spectrum, far below the frequencies used to power cell phones. Instrument landing systems utilize frequencies between 108-112 MHz, while mobile phones generally utilize the 800-1800MHz bands for functionality, depending on their age and technology. The distance between the frequencies for phones and VHF navigation equipment is great enough to not produce interference.
The reality is that there is not a single definitive instance when cellular technology was solely responsible for an accident. At any given time, countless passengers on a flight do not have airplane mode enabled nor their phones turned off. Aside from being far-removed from VHS frequencies used for navigation, individual PEDs simply are not powerful enough to interfere with aviation. Leaving a phone’s cellular functionality on only depletes the device’s battery as it fruitlessly searches for satellites that the phone is too high and moving far too fast to connect to for any reliable signal.
5G problems
Those who follow aviation news closely know about the troubles with the 5G C-Band rollout in the US in 2020 which did cause a safety hazard to aviation. The FCC allowed telecommunications companies to utilize 3700-3980 MHz for 5G networks. Radar altimeters, which are some of the most critical parts of an airliner’s auto-land capabilities, use 4200-4400 MHz. These frequencies are closer together than the previous frequencies, and this has led to issues.
Radar altimeters have a limited ability to “filter” spurious nearby frequencies according to RTCA Inc. RTCA conducted a thorough assessment of telecommunication interference with low range radar altimeters and found that individual phones on the ground do not interfere with radar altimeters. However, 5G ground transmission stations represent a threat and can cause a plane’s radar altimeter to not function properly if it receives nuisance signals from nearby frequencies. This poses no real problem on a clear day when the pilots can see the runway from miles away, but it affects landings on days when the visibility is limited since pilots rely on radar altimeters to decide whether to land or go-around.
In the past few years, airlines have installed 5G C-band filters on their fleets to eliminate radar altimeter interference from 5G telecommunications networks. Though no accidents resulted from this interference, many flights and passengers were impacted by the short-sighted rollout of the 5G network. Limitations existed for over two years at many airports affected by 5G interference. In a perfect world, the FCC would not have allowed 5G to utilize frequency bands so near to those used by aviation. Additionally, more tests could have been conducted on the front-end which would have allowed engineers to detect the problems and install filters on airplanes in anticipation rather than as a reaction.
Conclusions
Cell phones not being in airplane mode are not at all dangerous while flying. The best reason for placing a PED in airplane mode is to conserve battery while allowing you to connect to the airline’s in-flight Wi-Fi without your device attempting to roam and disconnecting your stream as a result. The rollout of 5G in the US market wasn’t properly vetted at its outset, but that issue has since been resolved. Barring massive changes in telecommunications and equally massive lapses in regulatory protocol, having a phone not in airplane mode while flying should never result in anything more than a dead battery when you pull it out of your pocket after the flight.
