Part Two - February 25th 2003
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.
Protocol:
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 ...
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."
Summary table
altitude (in feet)calls triedcalls successfulpercent success20004375%40004125%600012217%800012*11 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
February 25/03
'Project Achilles'
Final Report and Summary of Findings
A. K. Dewdney, 19th April 2003
During the early months of the year 2003, the author conducted three experiments to determine whether and how well cellphones could be operated from aircraft. The first flight (Part One) was essentially a probe of the experimental situation, to acquire some primary data and to work out a simple, readily implemented protocol. The results of Part Two (Diamond Katana 4-seater) have already appeared in these pages. The results of Part Three (Cessna 172-R) appear immediately below.
Since this completes the suite of experiments, it is appropriate to summarize the findings and to draw some conclusions. The conclusions are based partly on the experiments and partly on two other sources. (See Appendix B at the end of the report.) Expert opinion and eyewitness testimony are acceptable not only in court, but in certain scientific inquiries where events are of short duration or experiments are too expensive or impossible to carry out. Of course, eyewitness accounts do not carry the same weight as expert opinions or actual experiments, but the eyewitness accounts quoted below seem to be both consistent and compelling.
Disclaimer: The companies hired to assist in this experiment, namely Empire Aviation and Cellular Solutions, both of London, Ontario, Canada, acted as disinterested commercial parties, with no stake in the outcome or even knowledge of the purpose of the tests.
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Part Three - April 19th 2003
The previous experiment, called Part Two, established a distinct trend of decreasing cellphone functionality with altitude. It was conducted in a four-seater Diamond Katana over the city of London (pop. 300,000), Ontario in Canada, an area richly supplied with some 35 cellsites distributed over an area of about 25 square miles. The flight path was an upward spiral, punctuated every 2000 feet (abga) with a level circuit around the outskirts of the city. On each circuit a fixed number of cellphone calls were attempted by an expert operator employing a battery of well-charged phones broadly representative of those on the market both currently and in the year 2001.
(It should be remarked that not only is the cellphone technological base in Canada identical to its US counterpart, but Canadian communication technology is second to none, Canada being a world-leader in research and development.)
The purpose of Part Three was to test the effects of what might be called "Faraday attenuation" on the strength and success of calls. The presence of a metallic shell around some electronic devices can alter their behavior by its ability to attract and store electrons, especially electromagnetic waves. For this reason, the experimental craft was switched from the Katana, which is supposed to be relatively transparent to em radiation, to an aircraft with an aluminum skin, as below.
altitude (feet)calls triedcalls successfulpercent success200055100%40005360%600015640%800015213%Note: calls "tried" includes retired cellphones C1 and C4 above the altitude of 4000 feet where, in the opinion of the cellphone expert, they would have failed to get through, in any case. Failure to include them in the count would make the results at different altitudes non-comparable.
The results of this experiment may be compared to the results from Part Two where, instead of the Cessna, we used the Diamond Katana ....
Since the (1.5 mm) skin of the Cessna appears to have made little difference to the outcome of the experiment, the data of Parts Two and Three may be combined, as follows, to produce more reliable figures for the battery of test phones that were used in the experiment:
altitude (feet)calls triedcalls successfulpercent success20009889%40009444%600027830%80003539%The data from the first three altitudes appear to fit an inverse-linear model of attenuation. In other words, the probability of a call getting through varies inversely as the altitude, according to the formula:
Cont ...