9/11 One Small Piece Of The Puzzle

I live in Phoenix AZ and recently flew to Burbank California for a two day business trip. While giving the pre-flight instructs for seatbelts ect they ask that after we reach cruising altitude you may turn on your cell phones, but to make sure they get turned to game and airport mode only. So thinking to myself hey if you can turn them on THEN turn it to airport mode it really wouldnt affect the aircraft because if it was harmfull they wouldnt even let you turn it on period. So i decide to try a 9/11 experiment. Can i make an outgoing call at cruising altitude. I have the Virgin Mobile "Slice" Virgin mobile is a digital PCS network that actually uses Sprint's PCS network to make and receive calls anywhere sprint has coverage. So on the flight to Burbank i left my phone "ON" in my breast pocket just to monitor my signal bars. Sometimes 4 bars, averaged 2 bars, and occasionally zero bars. That was it. So on my return flight i called my sister before i left and told her if she gets a call from me to make sure she answers the phone. After the Captain stated we had reached our cruising altitude of 33,000 feet and were some 350 miles away from Phoenix I looked at my signal strength and it was 2-3 bars without ever losing signal. I hit the send button and waited. After it tried to connect my screen flased the 00:00 (Call Timer) and didnt connect. i tried for a total of ten times, and every time, even though i had plenty signal strength, never connected once. Everytime was 00:00 and would not connect. My sister said her phone didnt ring once with my number. Just my own personal experiment. Not an End all Tell all on cell phone usage mid-flight at 33,000 feet. Do i think multiple people got thru on that fateful day? Doubtful IMHO. Take it for what its worth, one small piece of the puzzle.

FYI - mobiles don't interfere with aircraft systems. The aircraft itself is flying through a sea of mobile phone communications that are stronger than any mobile phone can produce. Some airports even have masts on the airport itself. If anything, it is a ploy to get you to use the (more expensive) sat phone. I know several pilots who often forget to switch their own phones off, so they are on in flight.

Interesting experiment. I know down here on the ground that a good signal strength indication doesn't mean I can make a call. The base station transmitter is stronger than my own phones transmitter, so whilst my phone may be receiving a good strong signal (that is all that indicator actually means), it doesn't mean the base station can receive my transmissions (especially as the battery starts to go flat). The base station doesn't tell my phone how good its reception of my phone is.

I read recently that base stations select the station with the strongest signal, and that the reason you have to switch you phone off in flight is because if several stations get a similar strength signal, this results in a cascade failure of the network as the stations can't decide who should take the call, so they "shut down". This doesn't happen.

Imagine you are in your car, and you drive 500 miles. We already know that multiple base stations overlap to provide uninterrupted coverage as you move. This does NOT create a "cascade failure" in the network, although you could feasibly be in equal range of up to 5 base stations at once, because they vote on who is to take the call. Once the SNR (Signal to Noise Ratio) drops below a certain threshold, a poll occurs again as to which station will take the call. This is all completely transparent to the user, and never results in a failure of the network, or the ability of anyone on that base station to connect to it, although if you get 5,000 people trying to connect to a single station at the same time, it won't work due to a lack of bandwidth on that particular station to handle all the calls.

[edit on 14-4-2007 by mirageofdeceit]

[edit on 14-4-2007 by mirageofdeceit]