Last Updated on April 7, 2022
Flight attendants always ask you to switch all your devices to airplane mode during flights.
But why do they do this? Is airplane mode necessary? Why does it matter and what will happen if you don’t do it?
Well, don’t worry, you’re not going to crash, but there are still reasons to put your phone into airplane mode.
Let’s find out what the consequences of failing to switch on flight mode might be.
You’ll Be Breaking The Law
In the United States all radio, television, wire, satellite, and cable communications are regulated by Federal Communications Commission (FCC).
Here is the relevant law about using cell phones on planes:
Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not be operated while such aircraft are airborne (not touching the ground). When any aircraft leaves the ground, all cellular telephones on board that aircraft must be turned off. The following notice must be posted on or near each cellular telephone installed in any aircraft:
“The use of cellular telephones while this aircraft is airborne is prohibited by FCC rules, and the violation of this rule could result in suspension of service and/or a fine. The use of cellular telephones while this aircraft is on the ground is subject to FAA regulations.”
So airlines could be fined or suspended if you don’t turn on flight mode. This is why the Federal Aviation Administration and flight crew will tell you to switch on airplane mode.
You have to use airplane mode because airlines are not legally allowed to fly when cell phones are switched on.
However, a phone on airplane mode effectively becomes a little tablet, and portable electronic devices without cellular communication are not illegal. This is why airplane mode exists.
There Is Some Potential That Your Mobile Phone Can Interfere With The Airplane’s Communications Equipment
Airplane mode is important because phone signals could potentially cause electromagnetic interference with safety critical aircraft equipment.
When it comes to flying, it’s always better to be safe than sorry.
Flight attendants can sometimes tell when passengers have not turned on airplane mode.
A single phone not in flight mode might not cause anything to happen, but if every passenger had their cellular data switched on it might have an impact.
Sometimes pilots report hearing radio interference from cell phones in their headsets while trying to communicate with air traffic controllers.
That’s not a good thing.
You’ll be familiar with the sound you hear when your phone rings next to an audio system like a speaker.
That’s why you can’t turn off airplane mode in the air. This unpleasant noise is caused by parasitic demodulation and while it’s rare it’s not unheard of.
Modern cell phones operate using very low power and equipment in modern airplanes is insulated against interference so it’s less of a problem today. But back when cell phones were invented it was a bigger threat.
You’ll Cause The Cell Towers On The Ground To Work Harder
Airplane mode is also necessary because the cell tower network isn’t designed to deal with cell phones flying overhead at high speeds.
Cell phone towers are made to work with phones that are on the ground and not moving rapidly.
On the ground your phone connects to one local cell phone tower until you move to a different area.
At ground speeds, even if in a car, this doesn’t happen so frequently.
When you are flying you are going at 500 mph. If you are flying over an urban area with many towers your phone barely has time to connect to a cell phone tower before you have moved away.
This causes unnecessary overhead to the cell phone tower network, it’s a form of radio pollution.
This is one of the main reasons that the FCC demands that airplane mode is enabled when flying.
It’s a courtesy to the companies that run the cell phone networks to help them work without overhead phones rapidly connecting then disconnecting.
Your Cell Phone Battery Will Drain Quickly
Even if you don’t care about breaking the law, causing a buzz in the pilots ear, or burdening the cell tower network, you still have a good reason to turn on airplane mode.
Here is what will happen.
When you are up in the sky your cell phone will be continually searching for a tower to connect to.
After takeoff you’ll be out of range anyway, and when your phone can’t find a tower your phone will boost it’s power to search for a signal.
Not enabling airplane mode will cause your phone’s battery to drain quickly.
You can’t always charge your phone while on a plane, so you’ll land at your destination with your battery drained.
You’d Annoy Other Passengers If You Were Chatting On The Phone
These days some airlines offer in-flight wifi. It would be possible to make voice calls when airplane mode was enabled by using messaging apps like Whatsapp, Messenger, or Viber.
But in-flight voice calling is still prohibited by most airlines.
Many passengers simply don’t want other people blabbering on the phone next to them. It’s common courtesy.
Also, airlines want passengers to pay attention to safety demonstrations. And during take off and landing they want passengers to be alert and ready for evacuation in case anything bad happens.
If you don’t turn on airplane mode there is a slim chance that your phone’s radio emissions might interfere with the planes communications equipment.
It’s not a chance worth taking because your phone won’t work when you are flying anyway.
But if there was any great risk that forgetting to turn on airplane mode would cause a plane crash then phones would be outright banned on planes.
Modern airplanes have insulated their equipment to protect against radio interference. And modern phones are less powerful so there is less chance of that happening today than there was when the law was introduced.
But in aviation safety is paramount, so disabling your phone’s cellular communications is a sensible precaution.
When you are 7 miles up in the sky you are moving too fast and too far away to get a reliable cell phone signal. The cell phone towers point down at the ground where the people are, not up at the sky.
So there is really no reason for flight mode not to be enabled anyway.
While your phone might still work 10 minutes after take off and 10 minutes before landing your phone wouldn’t work for the rest of the flight.
It’s better to be safe than sorry, and it’s better to save your battery for after you land.