golfyankeesierra
I couldn't use my GSM (old Sony cdm-1000) a few hundred feet over a friend's house in a small town with good GSM-coverage.
There could be several reasons why your phone would not work. The most likely was interference. Each network has to reuse frequencies to cover the whole country. This is planned in some detail (in most companies anyway
) taking into account, distance, terrain, buildings and so on. This site explains some of the basics of frequency planning if you are that interested (its very dull really
)
http://www.privateline.com/PCS/HowPC...#anchor201958.
The problem arises in the air when you can “see” all the sites for many miles around and that brings in a lot of competing signals on the same frequency. If the phone cannot identify an individual site through the noise it will not be able to set up a call to start with or it may drop the call once it is set-up.
It is still possible to make a call while flying. You will just have an increased likelihood of a dropped call or having to make several attempts to set the call up. There are so many variables in how your phone sets up a call then maintains it and if any of them goes wrong it can fail.
I have made calls from 2,000 feet at about 120 knots and it has worked fine. On another occasion it simply would not set up the call at all. As I mentioned before although the GSM specs never envisioned it being used from the air and faster than 300KPH it is, in the right circumstances, possible. In the case you mention they were probably over a well designed and maintained part of the network.
Stringfellow Hawk
I asked the same question some time ago. After much discussion it was explained that while one phone is not really a big problem 150 being used in an aircraft can create a very big Electro magnetic field that is difficult, not to mention expensive, to protect against. So just get people to turn their phones off. Problem solved very simply, and cheaply
Aircraft_Nut9
I remember that case very well. Made me always check the location of my phone before I lift.