Adding: in some areas (EU and possibly India, unsure) the aircraft can be equipped with a low power cell tower called a picocell to both supply cell service to those on board and to prevent this issue.

The EU and US also don't require planes to be unaffected by WiFi or Bluetooth signals, but allow operators with aircraft assessed to be unaffected to allow passengers to use the aforementioned radios.

I've also seen some studies suggesting phones may pose slight interferences with the planes GPS system, but it didn't have much weight.

That actually makes all the sense as to why a phone dies 10x quicker when it has no service

There's a slight potential for all of those phones at max power to have an effect on the airplane's avionics. It's very unlikely, but they use an abundance of caution due to the potentially fatal outcome. What you described is true, but it's not the only reason.

Also 100 people with phones that trying to get a connection at max signal strength can interfere with plane communication.

From an IT standpoint, I think a single device obviously can't cause any issues. No single phone or sig al emitter could, unless specifically designed for it. Now the next I don't have as much confidence in, but I bet if even half or more use items, same deal. No big issue. If everyone at once decides or coincidentally all cause high emmisons, maybe that would be an issue.

However, how to you get everyone to understand that? You can't say most should do it, or ask half to do it. Too many would assume others should do it instead of themselves. Bystander effect etc. If you instead have attendants choose, how to be fair and not piss people off? If it really is a low chance but something you may possibly be sued for, also why do so?

Smartest thing for a large company to do is just ban it outright. It might only have a 5% chance of failure if and only if a passengers use their phones incessantly, and it would still be safer to just ban it outright.

Come on dude, you were being kidnapped and they didn’t want you to know where you were being taken. After it was reported that you had been told to turn off the GPS receiver they realized you knew what was up so they aborted the mission and they’re waiting for their next opportunity. It was a breakdown in operations which they had to hastily recover from. Theirs no way you don’t know what’s going on and keep accidentally thwarting these operations.

Autopilot won't be functional at this point though so when you switch on Airplane mode, also enable the manual flight control option so you can get the plane stable again.

I’ve heard it’s because the plane is moving so fast when taking off and landing that the phones will ping many different cell towers in rapid succession and that can wreak havoc on the network. It also makes your battery drain faster as it struggles to find a stable cell connection.

ETA: this comment explains it better: https://lemmy.world/comment/3968181

That actually was the case about 20 years ago, but nowadays it's not really a problem anymore

I made a separate comment on the same topic, but AFAIK its not to protect the cockpit - engine communication, but rather to prevent radio polution from your phone attempting to connect to ground stations as it is passing by above.

Edit: ^C^V my edit from the other comment:

while what I said seems to be true, radio transmitters, such as those in mobile phones, may interfere with some instruments, with GPS being most affected. However, if I understand correctly, these interferences are minor to none and I'm guessing issues start to arise when more devices are transmitting signals.

From my understanding, at worst, if enough interference from portable electronic devices is present, this could contribute to navigational issues, which could cause a crash. It will probably not cause the plane to nosedive or loose cabin pressure though.

I'll add my hearsay to everyone else's - whilst no reasonable piece of consumer electronics actually poses this risk, it's theoretically possible that a particularly recklessly designed device could. The airlines need some sort of assurance for liability/insurance reasons, and rather than submit every electronics manufacturer to get every device tested and accredited, they came up with 'airplane mode' as a compromise.

I've read it's to reduce distractions while the flight attendants give instructions to the passengers.

Interesting that both lithobreaking and lithobraking work.

Why would the crew care about my phone trying to connect to cellphone towers?