Cell Phone Calls
Are Cell Phone Calls From Aircraft In Flight Possible?
The experiments described here have been used to argue that the phone calls from Flight 93 were impossible. The arguments overlook several important facts that render the experiments essentially inapplicable to the reports of phone calls from the jetliners commandeered on 9/11/01.
Prof. A.K. Dewdney conducted experiments in which his team attempted cell-phone calls from a light airplane at different altidudes over semi-urban areas. Here is the report from one in a series of these experiments. 1
'Project Achilles' Report
Part Two - February 25th 2003
- Diamond Katana four-seater (Empire Aviation)
- cellphones: C1, C2, C3, C4 (See appendix for descriptions.)
- Corey Barrington (pilot)
- Darren Spicknell (operator - technician for Wireless Concepts, Inc)
- Kee Dewdney (director)
- Pat Dewdney (ground recorder)
Weather: unlimited ceiling, light scattered cloud at 3,000 and 25,000 feet, visibility 15 miles, wind 5 knots from NW, air temperature -12 C.
For this experiment, we flew a circular route, instead of the elongated oval. The circle centred on the downtown core and took us over most of the city suburbs. All locations below are referred to the city centre and are always about three miles distant from it.
At times specified by the director, the operator made a call to a specified number, stating the code number of the cellphone (1 to 4) and the altitude. The receiver recorded whatever was heard and the time the call was received. At the first three altitudes of 2000, 4000, and 6000 feet abga each cellphone was used once. At 8000 feet abga, only C2 and C3 were tried, C1 and C4 now being hors de combat.
Results with timeline:
time (pm) call no. C# loc. operator recorder 5:05 started taxi to runway 5:12 takeoff 5:14 at 2000 feet (above-ground altitude) 5:15 Call #1 C1 N success not very clear 5:17 Call #2 C2 W success not very clear 5:19 Call #3 C3 SW failure 5:21 Call #4 C4 S success not clear/ breaking up 5:24 climbed to 4000 feet abga 5:25 Call #5 C1 NE failure 5:26 Call #6 C2 N success clear 5:27 Call #7 C3 NW failure 5:29 Call #8 C4 W failure 5:33 climbed to 6000 feet abga 5:34 Call #9 C1 SE failure 5:36 Call #10 C2 E failure 5:37 Call #11 C3 NE failure 5:38 Call #12 C4 N failure 5:39 Call #13 C1 NW failure 5:40 Call #14 C2 SW success clear 5:42 Call #15 C3 S failure 5:43 Call #16 C4 SE failure 5:44 Call #17 C1 E failure 5:45 Call #18 C2 NE failure 5:45 Call #19 C3 NE success breaking up 5:46 Call #20 C4 N failure 5:49 begin climb to 8000 feet abga (cellphones 2 and 3 only) 5:50 Call #21 C2 W failure 5:50 Call #22 C3 SW failure 5:51 Call #23 C2 S success buzzy 5:53 completed climb to 8000 feet abga 5:58 Call #24 C3 SE failure 5:58 Call #25 C2 E failure 5:58 Call #26 C3 E failure 5:59 Call #27 C2 NE failure 6:00 Call #28 C3 N failure 6:01 Call #29 C1 N failure 6:01 Call #30 C2 NW failure 6:02 Call #31 C3 NW failure 6:02 Call #32 C4 NW 6:15 landed at airport
To the extent that the cellphones used in this experiment represent types in general use, it may be concluded that from this particular type of aircraft, cellphones become useless very quickly with increasing altitude. In particular, two of the cellphone types, the Mike and the Nokia, became useless above 2000 feet. Of the remaining two, the Audiovox worked intermittently up to 6000 feet but failed thereafter, while the BM analog cellphone worked once just over 7000 feet but failed consistently thereafter. We therefore conclude that ordinary cellphones, digital or analog, will fail to get through at or above 8000 feet abga.
It should be noted that several of the calls rated here as "successes" were difficult for the Recorder to hear, witness description such as "breaking up" or "buzzy."
altitude (in feet) calls tried calls successful percent success 2000 4 3 75% 4000 4 1 25% 6000 12 2 17% 8000 12* 1 1 8%
* includes three calls made while climbing; last successful call was made from just over 7000 feet.
The four cellphones operated via four different cellular networks (cellsites). Because calls were made from a variety of positions for each network, it cannot be said that failures were the fault of cellsite placement. the London, Ontario, region is richly supplied with cellsites belonging to five separate networks.
It may be noted in passing that this experiment was also conducted in a radio-transparent aircraft with carbon-fibre composite construction. Failure to make a call from such an aircraft with any particular brand of cellphone spells automatic failure for the same cellphone from a metal-clad aircraft flying at the same altitude. A metal skin attenuates all cellphone signals to a significant degree. It may safely be concluded that the operational ceiling for cellphones in aluminum skin aircraft (most passenger liners, for example) would be significantly lower than the ones reported here.
It may therefore safely be concluded that cellphone calls from passenger aircraft are physically impossible above 8000 feet abga and statistically unlikely below it.
A. K. Dewdney
Appendix - Cellphone types, networks (courtesy of Darren Spicknell)
C1 Motorola i95cl - Telus Mike Network - 800 Mhz IDEN
C2 Motorola StarTac - Bell Mobility - 800 Mhz Analog
C3 Audiovox 8300 - Telus PCS Network - 1.9 Ghz CDMA / 800 MHz
C4 Nokia 6310i - Rogers AT&T - 1.9 Ghz GHz GSM. (Tri-Band - Has an
1.8 GHz and 900 Mhz GSM these are European frequencies)
IDEN - Integrated Digital Enhanced Network
CDMA - Code Division Multiple Access
GSM - Global Systems for Mobile Communications
Power output of these handsets. The Nokia 6310i and Audiovox 8300 when in digital mode will output 0.2 Watts.
When the Analog Motorola StarTac is operating it is at 0.6 Watts optimal.
When and IF the Audiovox 8300 is in analog mode it will operate at 0.6 Watts (However, this is not normally the case - you will see wattage levels around 0.52 - 0.45 approximately)
Both the Telus Mike (C1) and Motorola StarTac (C2) operate in the 800 MHz range. This will allow the signal to travel at a great distance. However, the IDEN (Mike) network has fewer site locations and is a newer Digital network. Most digital technologies operate on a "all or none" basis. When it has signal it will work well. As the signal fades, one hears no static, but some digital distortion just before the call drops.
Mike Network: Newer, all-digital network with modern antenna design, and fewer cellsites
Bell Mobility Analog: Older, analog network with less focused antenna design but many cellsites
Telus PCS: Newer, digital network with multiple frequencies, modern antenna design, and many cellsites
Rogers GSM: Our newest digital network with modern antenna design and many
A. K. Dewdney,
February 25th 2003