[jiggawatts]

Maybe about half the passengers actually turn airplane mode on. Or turn it on for their phone, but forget their tablet and smart watch.

It's just theatre. It's there mostly to stop you playing with your phone and pay attention to the flight attendant doing the safety speech. One time, many years ago when phones were literally the size and weight of bricks and avionics weren't prepared for the interference of these new fangled "moveable phones", there may have been a problem with some of them, so the FAA put a rule in.

These days, every single passenger has at least one 4G or 5G device. If this was truly a problem, really truly actually causing radio interference, this wouldn't be allowed. You'd have to walk through an RF detector at the gate, and they would confiscate your devices and put them in a Faraday cage.

Do you know why they don't confiscate your phones?

Because it doesn't matter. It doesn't matter because avionics has had to deal with RF interference from mobile phones for decades, and no commercial plane would be deemed airworthy if it had any such problem!

Famously, some of the victims of the 9/11 hijackings got to make phone calls from the air, and/or received SMS texts notifying them of what happened to the other planes.

That was TWENTY YEARS AGO!

[jdavis703]

> It's just theatre. It's there mostly to stop you playing with your phone and pay attention to the flight attendant doing the safety speech.

They frequently give the safety demonstration before requesting people turn on airplane mode. And besides, there’s no safety demonstration when landing.

> If this was truly a problem, really truly actually causing radio interference, this wouldn't be allowed.

And they would drug and alcohol test pilots before flight, yet you can still read NTSB reports showing toxicology in fatal crashes.

> Famously, some of the victims of the 9/11 hijackings got to make phone calls from the air, and/or received SMS texts notifying them of what happened to the other planes.

Those were satellite phones (or used special ground-based receivers) they weren’t regular cell phones. And they were embedded in your seat-back and presumably certified as being airworthy.

[bananabreakfast]

Their cell phones didn't use cell phone technology?

What on earth are you talking about?

[p_l]

The calls that I recall being reported on used telephones available to flight crew for communications unrelated to flight and possibly made available for crazy prices to passengers.

You generally can't receive cell phone signal at segment of airliner flight except immediately after takeoff and in final stages of landing, due to optimizations involved in providing said signal (directional segment antennas, with attempts to beam-form towards specific terminals in latest versions). In practice I had hard time and required special tricks to keep a call running above 500m AGL and it probably depended on BTS located on hill above my reference point.

[ceejayoz]

I thought most of the 9/11 passenger calls came from the eye-poppingly expensive satellite phones in the seat backs.

[p_l]

There actually tends to be avionics interference from mobile devices, especially outside 2.4GHz band (which is a "junk" band because of airliners - unlicensed use of 2.4GHz band exists so that airliners could use microwave ovens).

Airplanes actually aren't tested for mobile phone interference unless the plane is going to explicitly allow use of in-flight wireless internet. Yes, with modern devices, you have much less risk of interference, but interference happened in the past, and the rule stays mostly to lower the amount of loose, hard and heavy devices that become possibly dangerous projectiles in case of Rejected Take-Off or a crash.

After all, it's easier to put a "theatre" on than try to use reason with barely mentally present (on average) and possibly unruly passengers.

[dataflow]

> It's just theatre.

My understanding is it's an FAA rule to prevent talking on the phone during flight (as well as listening to crew like you mentioned, etc.), not some kind of theater (which I understand would be an FCC rule, ostensibly to prevent interference).