Originally Posted by
Section 107
seriously though: aren't the "airplane" modes for cellphones just to keep the phone from using lots of energy searching for signals and not "to avoid interference with avionics"?
No, the airplane mode is for two reasons:
1. The FAA prohibits the use of anything that transmits in flight due to the possibility of interference with aircraft systems.
2. The FCC prohibits the use of mobile phones while airborne because the ground networks were designed around the line-of-sight RF propagation limitations and channels were re-used once out of line-of-sight of the nearest cell using that channel was exceeded. When you elevate the radio (phone), you greatly extend the line-of-sight range and make the channel being used unusable on as many as several dozen other cells.