I am a senior design RF cell phone engineer ( cellular/CDMA engineer) and have designed systems for Sprint, Verizon and Alltel. I have 2 FCC licenses and have worked in the industry for 13 yrs. That out of the way…
OK all of the new handsets are .6 to 1 watt max.
From what i read several calls were made on flight 93 some were reported to last as long as 20 minuits. NO WAY ! We design these systems to work on the ground, ususally providing "downtilt" to the antenna, so the signal gets pointed downward.
There are calculations to do this. The range for a call site is 5 to 20 miles max, but that is on the ground. The handshaking is now refered to in digital as soft handoff, or hard handoff if you are going between systems, or in an analog mode. most phones today are now digital, though some can do both. for a handoff to occur( going from one cell to another) the system needs to have a neighbor list setup, telling the phone which cell is next on the list( i have made around 100 of these). at 500mph, the phone would have passed several sites and it would try to handoff to a site already passed. The phone can be in handoff with up to 3 sites at one time, but generally this can make things worse as it will degrade the signal.
Also inside of a metal plane, the signal degrades
( it does in a car, or building by 3 to 6 db or more)
I have done in building testing for years. each 3 db means 1/2 power. inside a metal plane i would guess it would be about the same, if you stick the antenna next to a window, MAYBE only 1 to 2 bd loss, but still a loss. i havent tested it, but i have a lot of experience in this area. Note there is a lot of messaging between the phone and the site, and at that height the signal would be quite low and the phone would get confused as to which site it is on.
I dont know the height the plane was at at that time, but the higher it is, the more signals come in, which degrades the quality and confuses the phone more, not to mention lowering the signal level.
One more thing, in remote areas, where these calls were made i believe, these companies do not build many sites. The sites cost 1/2 million a peice or so.
Just try driving from 1 city to another through a very rural area and see if your phone works, we point the antennas down the highways to get the most out of each site. Planes do not fly along highways.
when i first heard this, it didnt add up in my head.
my engineering page