why do they ask us to keep our devices on airplane mode on a plane but the WiFi is allowed?
In: Technology
Airplanes use all kinds of radios to do various different things. The most common use that everyone knows about is to talk to Air Traffic Control. Planes also use radio waves to measure things like distance above the ground when they’re below a certain altitude, report information about the plane back to aircraft mechanics, exchange short text messages with Air Traffic Control, GPS, reporting information about the flight to other airplanes to avoid collisions, and a lot more. Airplanes also use radio to help land in bad weather conditions. Some systems are critical to the safety of the plane in flight, so any interference could be a huge issue!
Back when cellphones were super new, there was a lot of concern over whether or not the radio waves used by cellphones could interfere with any of the instruments on the airplane that use radio waves, so it was decided that all phones had to be turned off “Just to be safe”. Eventually, phones got “Airplane mode” where you were able to disable all radio communications entirely so that you could still use your phone to play games or watch a downloaded movie so that became the de-facto standard that they told everyone to use.
But after many years, it was figured out that nah, some things don’t really interfere with instruments on plane and we got the capability to beam internet to airplanes in flight so it was decided that it was OK for people to use things like WiFi and also Bluetooth while on a plane.
But, as others have mentioned, it’s also to save battery. When your phone is really far away from a cellphone tower, it’s going to try and connect to one anyways to get service. To do this, it will send out radio waves at increasing power until it either hits the maximum power it can transmit, or the battery runs out. Since cellphone towers are pointed at the ground, you’re never going to get a signal up in the air unless you’re below a certain altitude. And because on a plane you could be sitting there for hours at a time with no service, it will drain your battery very quickly.
[However, it has recently been found that certain types of 5G *can* actually interfere with airplanes](https://www.faa.gov/newsroom/faa-statements-5g). Specifically, it can interfere with the radio equipment that planes use to figure out how high they are above the ground when below a certain altitude. This part is called a “Radio Altimeter” and most modern airplanes are fitted with them. After a lot of back-and-forth between cellphone companies, organizations like the FAA, and airplane manufacturers, they have decided on certain restrictions surrounding the particular frequencies that cause interference to Radio Altimeters. It’s perfectly safe now, but there were reports in the early days of 5G from pilots who reported issues with their Radio Altimeters.
Because of all of this, it’s really suggested that you follow the flight attendant’s advice and keep your phone in airplane mode. Besides, you won’t get a signal anyways!
You will receive all kinds of stories as to why, and all of them are wrong. If signals were to interfere with the plane systems, do you really think they would let you decide to switch it off or not? LOL. THE absolute only reason is two folds: 1) from the early days, the notion that it may affect the plane has stayed – fear is a difficult to let go. 2) so that everybody DONT try to call their friends and chat for 5 hours straight next to each other. We would go insane. Here i explained it. Any comment that says interference, signals etc dont know anything unfortunately.
Like most aviation (passenger) security it’s largely irrelevant and an artifact of poor knowledge and nervousness.
Fun fact: airplane mode on cell devices is largely archaic. It spawned from an issue with cell towers not the plane. Devices flying through cell locations at hundreds of miles per hour could be in and then out of the same cell faster than the tower could respond, often times crashing the cell tower in the process. As planes got higher and towers better this became a non issue but these days it’s kept around as a better safe than sorry in regards to interference
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