Just to clarify what I meant, the flight that entered the Pentagon without authorization was on a glide slope that went so low as to clip the light poles, so it was under 300 ft for a few seconds at least.
The flight that plunged into the earth at Shanksville was under 300 ft for less than a second.
So these two could theoretically have made phone calls even if the 300ft ceiling was the limit, but the time element to do so was very short (miliseconds for one).
The other two planes that hit the NY towers are on a long glide slope (there’s an animation available somewhere) and hit the towers roughly 800 ft from the ground after descending gradually. Cellphones could (and did, IIRC) make connections just prior to the hit; they weren’t much higher than some skyscrapers for a few minutes.
Nevertheless, in spite of your buddy’s “palm tree” analogy, I know of no way that radio signals can be bent after leaving the tower other than being reflected off of certain stratospheric layers (miles high), the earth, or solid objects. (And the frequencies used by cellphones don’t reflect well in the stratospheric layers.) The engineers try to concentrate signals in the usable area close to earth, but a few miles away, in clear air, those signals are much less concentrated and more unpredictable. A low-flying plane is well within a reasonable signal pattern for several towers in most locations.
No, the US is pretty evenly split between CDMA and GSM. There used to be TDMA and iDEN networks too, but I think those are gone. I don’t know if AMPS is hanging on still or not.
Also no. Or at least pretty sure no for the big iron and definitely no for private aircraft. Non-military aircraft use frequencies around the 120-130 MHz range for voice and digital ACARS communication.
Again, no. The “turn your cellphone and ALL electronics” announcement is notionally to prevent internal interference with the autopilot and navigational electronics.
Anecdotally, I’ve had no problem using my phone in a private aircraft at a couple thousand feet. If towers only covered up to 300ft, then anyone above the 30th floor of a building would be SOL. .
Maybe, but if you ever are flying your plane, circling over your house, and spot a dude making off with your trailer, now you know that you can probably use your cellphone to call in airstrikes and rain destruction on the bastard without having to land first.
I told JR I was going to use him as a cite. This is going to be fun, he is paying the next time we go out for sure. The funny thing is that I was wondering if he was full of it when he was using the “fingers” analogy. Thanks Dopers for fighting my ignorance now I have to kill JR. Cheers all
Question - how was this pilot able to deviate from his flight plan to pursue the robber? Don’t pilots have to file flight plans, and stick to them (absent in-flight emergency)?
Flying using visual flight rules outside controlled airspace you can do what you like. Otherwise within controlled airspace you can get area clearances, you could be cleared to operate below 2000’ within a 10 Nm radius of your house for example.
iDEN is still alive here, and in many other countries. It’s being phased out in the US, but it hasn’t happened yet.
FWIW, iDEN is similar to GSM.
Side note - I had a layover in Guam on a vacation once, and turned on my Nextel phone. It’s the only time I saw an iDEN phone roam onto another network. And I found a bug at the same time.
-D/a
