Myths Debunked – Do Mobile Phones On Airplanes Cause Signal Interference?

It’s something that all of us who have ever gone anywhere near a plane have heard time and time again – “please set your portable electronic devices, including any mobile phones, to flight mode.”

Have you always actually listened to the instruction, though? No, we don’t mean merely ‘listened’ – we mean, actually followed the instruction. If you’re shaking your head right now, it seems that you’re in plentiful company.

According to a Consumer Electronics Association (CES) survey cited by CNN, nearly one in three airline passengers claimed to have left on a portable electronic device during a flight over the course of the previous year.

That’s an awful lot of ‘signals interfering with the plane’s navigational system’, to quote the parlance customarily used by those fearful that leaving a mobile phone on while in the air could pose a danger to the plane – or even bring it down.

Now, we’re sure that you’ve never heard of a plane crash being attributed to someone being too absorbed in Angry Birds to remember to switch their iPhone off after their plane took to the air. And, yeah, neither have we.

It seems a pretty ‘open and shut’ case, then – it’s all a load of bunkum, isn’t it?

Have there been any incidents of dangerous mobile phone interference?

CNN, at least, agreed with us in their 2013 article on the subject, entitled “Can your cell phone bring down a plane?” Writers Mike M. Ahlers and Rene Marsh observed: “We can find no instance in which electromagnetic interference from a portable electronic device brought down a commercial plane or was a contributing factor in an accident.”

However, that’s not the end of the story. After all, as Ahlers and Marsh admitted, between 2003 and 2009, there were 75 instances of suspected electronic device interference, with mobile phones implicated in 29 of them, as shown by International Air Transport Association research.

That’s a pretty darned modest ratio of one event per 283,300 flights… but it’s not absolutely nothing.

An article by Air & Space/Smithsonian magazine provides clearer detail on one incident, in particular: that of a Boeing 737 airliner on an instrument approach to Baltimore-Washington International Airport one night in March 2003.

It was reported by the captain of this flight that while his course indicator – otherwise known as a localiser – had been centred during the approach, it then suddenly showed a full deflection. In the words of Air & Space/Smithsonian writer John Croft, “just then the aircraft, flying on autopilot, broke out of the clouds – at an altitude of 2,500 feet and a full mile off

The pilot’s theory was that having received word from air traffic control that the United States had started attacking Iraq, his announcement of this news to his passengers prompted one or more passengers to place calls on their mobile phones.

As you might imagine, his own suggested means of prevention was to never announce anything to passengers that might encourage them to reach for their mobile phones while their plane is still in the air.

Is that as serious as mobile phone interference has ever gotten, though?

The sad fact is that we actually don’t completely know. As observed by The Telegraph’s travel news editor Hugh Morris in a 2016 article for the newspaper – entitled “The real reason you’re told you put your mobile in flight mode” – there have been at least two serious incidents in which mobile phones have been implicated.

Those incidents are the unsolved crash of a Crossair plane in Switzerland in 2000, when the autopilot was confused by spurious transmissions, and a fatal crash in Christchurch, New Zealand in 2003.

These, though, are admittedly extreme examples.

The reality? It’s a complex issue

As Croft mused in his 2004 article, “The fact that more than four decades of study has not cleared up the uncertainty that remains is testament to the complexity of the issue.”

It’s a certainly a more complicated issue than we have the space to investigate in minute detail here at Protect Your Gadget. In any case, none of our own analysis would bring us closer to a definitive answer to the billion-pound question: “Could your mobile phone actually bring down your plane?”

If, though, we’re simply referring to the matter of whether mobile phones on airplanes cause signal interference, there’s little doubt about that. In a technical sense, there is scope for phones to interfere with the plane’s instruments, but probably only to a small degree.

A pilot blogging on, in fact, has said that the interference that mobile phone signals cause registers on the headsets of the flightdeck, in the same manner that one might have experienced on speakers affected by a nearby mobile: “dit d-dit d-dit d-dit…”

The author said that while he “actually heard such noise on the radio while flying… it’s not safety critical, but is annoying for sure.”

So, in conclusion?

Yes, your mobile phone left on may indeed have been a source of minor annoyance to a pilot from time to time. But with the latest aircraft being “hardened” against electromagnetic interference, despite the increasing sophistication of the devices potentially capable of such interference, it seems that you don’t have too much reason to worry.

Still, there’s a reason why such bodies as the Federal Aviation Administration (FAA) have tended to take a ‘better safe than sorry’ approach to their guidelines on the subject, even if much responsibility has been left to the airlines.

That’s because, well… it really is better to be safe than sorry. So let’s just leave your phone switched off or on airline mode anyway, yeah? Even if you do receive news while in the air anytime soon that American and North Korean hostilities have just broken out…