Why aren’t we allowed to use our phones on airplanes?


I’m not talking about playing games or watching stuff on flight mode, I’m talking about making calls and texting or using mobile data.

As a kid my parents told me that it interfered with the pilot and they couldn’t see but I realised that’s the same reason they don’t like the overhead light in the car.

In: Technology


Historically, aircraft instruments and systems that were vital for critical aircraft operations (especially takeoff and landing, but also navigation) were unshielded against cellular radiation from phones. The worse case I can think of is with ILS, instrument landing system, where the plane relies on radio communication with devices on the ground in order to make a safe approach to the runway. Especially when the pilot cannot make a visual approach. These could be interfered with, and there’s a risk that false readouts could lead to errors, given that phone technology is constantly changing like with 5G.

Phones have never caused a crash, but they have caused issues for pilots in the past. Nowadays, there are systems which actively block signals whilst in the air (IIRC, which is why you usually don’t have signal in flight even with a cell tower in line of sight), but some aircraft are able to route cell data through a system on the plane which can safely connect people to make calls and texts. There are even some carriers which offer WiFi services, however these can be extremely expensive as they rely on satellite communication.

Your phones use the same bandwidth used by flight crew to communicate with ground crew. Pilots have to regularly communicate their status to so called “earth stations”. As they are too high in the sky, they need lot of power to send the messages to the station. If your phone’s are on, they too communicate with base stations (of your network operator) which interferes with the signals sent by flight crew. To mitigate this, they might need more power, which still doesn’t guarantee successful message transmission. As we don’t want to interfere with more important messages being sent, it is usually advised to put the phones on flight mode.

I filmed an interview 8-9 years ago with the head of the FCC. He explained that it had more to do with messing up ground communications hopping from transmission tower to tower like that.

Historically early phones would sit on similar bandwidths to some of the airframe systems. Do you remember placing early phones near speakers and getting interference?

Now some of those systems could be critical to the navigation and control of the aircraft, coming into land suddenly get feedback throwing guidance off.

Although modern phones and modern aircraft will not interact with each other it is safer to have a blanket ban incase your on a plane that does react to some phones.

There was some early suspicions that it might interphere with aircraft systems, but that proved to be a non-issue.

What is a problem, though, is that when a phone is high up, it will reach many base station, and it’ll be moving fast, so it’ll have to switch stations often. This cause problems/load in the phone network.

Put a phone next to your computer speaker and hear the mess of a sound it comes out.

That’s your phone signal disturbing an audio channel.

Now, planes cables are shielded for that, but do you want it take the risk of 300 phones on board trying to deafen your pilot radio coms? Because that means you gonna incapacitate his radio, so he can’t com to ground, so 2 interception fighters show up and escort you to an airport and you don’t get to destination….

To add insult to injury: the plane is a big faraday cage, so your phone wouldn’t get any decent signal anyway as son as you take off. Then when airborne you won’t be covered by cellular towers anyway.

So it’s useless and if 300 people do it at once, also a potential nuisance for the flight.

One of the reasons is that when not in flight mode, phones will continuously be searching for both signal and WiFi connections. For old and/or unstable phone batteries, this power consuming activity may cause the battery to catch fire. In an airplane cabin, this would be dramatic and a real threat to safety. So it is mainly a precaution against fire, and much less an issue of signal interference etc.

The only real answer is that they can cause issues with networks on the ground due to the plane’s height and speed.

The FCC ensures there is no bleedover between cellular communications and any airplane communications system. They are all designed to work on very specific frequencies. There has never been any proof that a cell phone interferes with anything on the planes.

It has nothing to do with electromagnetic interference with airplane systems.

Having worked with pilots, maintainers, and people in the airline industry its actually because planes are moving too fast near the ground that they switch cell towers too often and cell carriers couldn’t figure out how to bill you. They asked the airlines to just have people turn them off until they were over 10,000ft and out of range of the towers. The problem is mostly solved since there are only a couple large carriers now (Verizon, AT&T, T-mobile) and its more of a hold over and to hopefully have people pay attention to flight attendant instructions.