September 13, 2001: Series of Unusual Circumstances Said to Make Hijacked Passenger Cell Phone Calls Possible

It is reported that the many phone calls made by passengers from the hijacked flights are normally technically impossible to make. A major cell phone carrier spokeswoman claims, “Those were a series of circumstances that made those calls go through, which would not be repeated under normal circumstances.” Supposedly, the calls worked because they were made when the planes were close to the ground and they were kept short. [Wired News, 9/13/2001] However, many of the cell phone calls were made from high cruising altitudes and lasted ten minutes or more. The New York Times later reports, “According to industry experts, it is possible to use cell phones with varying success during the ascent and descent of commercial airline flights, although the difficulty of maintaining a signal appears to increase as planes gain altitude. Some older phones, which have stronger transmitters and operate on analog networks, can be used at a maximum altitude of ten miles, while phones on newer digital systems can work at altitudes of five to six miles. A typical airline cruising altitude would be 35,000 feet, or about 6.6 miles.”
[Slate, 9/14/2001] A spokesperson for the AT&T phone company notes that cell phone networks are not designed for calls from high altitudes. She suggests that “it was almost a fluke that the calls reached their destinations.”
[Wireless Review, 11/1/2001]