GPS != cell networks, and I'm asking what is actually happening, not for a hypothetical guess (which I can make too).
Also you asked if carriers need a backdoor, which I answered: "Wouldn't that need a backdoor in the OS's GPS software/driver?"
PS asking a question and berating any answer you don't like is not exactly optimal strategy for getting people to answer your future questions.
In airplane mode it _shouldn't_ be sending that data.
With aGPS, the cell phones can download up to date GPS almanac from the tower instead of having to lock to GPS satellites to get it.
The parent commenter explicitly write "A-GPS which uses triangulation".
That is simply not true.