[miki123211]

It's not "known nonsense", but not for the reason you think. There's a small risk of your phone connecting to some random carrier located in whatever country you're currently flying over. For some smaller / third-world countries, this can be quite expensive, cents-per-megabyte isn't unheard of.

[avar]

Every time this is brought up people come out of the woodworks with post-hoc rationale for this rule that has no basis in historical fact. This comment is good example.

Why would the FAA and other aviation regulatory agencies care about your phone bill?

[lxgr]

I completely agree on GPs statement being absurd post-hoc rationale, but interestingly, this rule is actually coming from the FCC, not the FAA [1], with the FAA only indicating support for it [2].

The motivation is supposedly cellphones at high altitudes interfering with far-away cell towers that are reusing the same frequency at a distance that would normally make interference very unlikely, given the radio horizon and everything.

I highly doubt that that would still be an issue modern networks couldn't handle (also given that most other countries don't have a corresponding law on their books, as far as I know), yet here we are.

[1] https://www.law.cornell.edu/cfr/text/47/22.925

[2] https://www.faa.gov/documentLibrary/media/Advisory_Circular/...

[miki123211]

It's not the reason the rule was implemented, it's not something the FAA cares about, but this doesn't change the fact that it's still a good idea in some cases, rule or no rule.

[lxgr]

By that logic, many more things ought to be declared illegal by completely unrelated regulatory bodies. It would be a bit like the FDA banning gambling, or the SEC reinstating prohibition.

[lxgr]

If that were the motivation, airlines should also display a "no credit cards" icon to protect you from overspending on the in-flight drinks service.

> cents-per-megabyte isn't unheard of.

If only! Double-digit dollars per 100 kilobyte aren't unheard of.