Cell Phones Do NOT work at High
Altitudes
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'Project Achilles' - Final Report and Summary of Findings by 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. ------------------------------------------- Part Three - April 19th 2003The 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. Equipment:
Personnel:
Weather: unlimited ceiling, light scattered cloud at 5,000, solid/broken 24,000 feet, visibility 12 miles, wind 11 knots from SSW, air temperature +19 C. For this experiment, we flew the same circular route as we did in Part Two, The circle centered 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 two 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 5) and the altitude. The ground recorder noted whatever was heard and the time the call was received. At the first two altitudes of 2000, 4000 above ground altitude (abga) each cellphone was used once. At 6000 and 8000 feet abga, each cellphone was used twice only C2, C3, and C5 were tried, C1 and C4 being hors de combat. Results with timeline:
The following table summarizes the results:
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:
To make the results comparable, however, cellphone C5 was omitted from the calculations, since it was not used in the first experiment.
AnalysisSince 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:
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: Probability of success = k/altitude, where k is a constant It will be noted that the values of k implied by these data, at least up to 6000 feet abga are remarkably consistent. However, at 8000 feet the k-value falls precipitously, implying that a different regime may be in play.
The expected model of attenuation with distance is of course inverse squared, a natural consequence of the three dimensions that any uniform radiation must travel through. Inverse squared attenuation follows a slightly different pattern or formula: Probability of success = k/altitude² To estimate k, it seems reasonable to use the data from 4000 feet and 8000 feet as benchmarks for the calculation of the constant k (not the same constant as was used in the foregoing analysis, of course.) At 4000 feet abga the implied k-value if 7,040,000, while at 8000 feet, the implied k-value is 5,760,000. although here again the k-value appears to drop (indicating that the actual attenuation may be worse than inverse squared), we use an average of the two estimates, following our consistent practice of always giving the benefit of the doubt to the cellphones, so to speak. Taking an average value of k = 6,400,000, we obtain the formula, Probability of success = 6,400,000/altitude² Using this formula, we can get a best-case estimate for the probability of cellphone success from a slow-moving light aircraft, as summarized in the following table.
Private pilots flying light aircraft are nowadays familiar with the fact that they may use their cellphones to make calls to the ground, at least if they are not higher than one or two thousand feet. Above that altitude, calls get rather iffy, sometimes working, sometimes not. The higher a pilot ascends, the less likely the call is to get through. At 8000 feet the pilot will not get through at all unless he or she happens to be using a cellphone with the same capabilities as C5 (See appendix A.) But even that cellphone begins to fail at 6000 feet. Calls from 20,000 feet have barely a one-in-a-hundred chance of succeeding. The results just arrived at apply only to light aircraft and are definitely optimal in the sense that cellphone calls from large, heavy-skinned, fast-moving jetliners are apt to be considerably worse. ConclusionsIt cannot be said that the Faraday attenuation experiment (Part Three) was complete, in the sense that the operator normally held the phone to his ear, seated in a normal position. This meant that the signals from the test phones were only partially attenuated because the operator was surrounded by windows that are themselves radio-transparent. Although we cannot say yet to what degree the heavier aluminum skin on a Boeing 700-series aircraft would affect cellphone calls made from within the aircraft, they would not be without some effect as windows take up a much smaller solid angle at the cellphone antenna. Signals have a much smaller window area to escape through, in general. As was shown above, the chance of a typical cellphone call from cruising altitude making it to ground and engaging a cellsite there is less than one in a hundred. To calculate the probability that two such calls will succeed involves elementary probability theory. The resultant probability is the product of the two probabilities, taken separately. In other words, the probability that two callers will succeed is less than one in ten thousand. In the case of a hundred such calls, even if a large majority fail, the chance of, say 13 calls getting through can only be described as infinitesimal. In operational terms, this means "impossible." At lower altitudes the probability of connection changes from impossible to varying degrees of "unlikely." But here, a different phenomenon asserts itself, a phenomenon that cannot be tested in a propellor-driven light aircraft. At 500 miles per hour, a low-flying aircraft passes over each cell in a very short time. For example if a cell (area serviced by a given cellsite) were a mile in diameter, the aircraft would be in it for one to eight seconds. Before a cellphone call can go through, the device must complete an electronic "handshake" with the cellsite servicing the call. This handshake can hardly be completed in eight seconds. When the aircraft comes into the next cell, the call must be "handed off" to the new cellsite. This process also absorbs seconds of time. Together, the two requirements for a successful and continuous call would appear to absorb too much time for a speaking connection to be established. Sooner or later, the call is "dropped." This assessment is borne out by both earwitness testimony and by expert opinion, as found in Appendix B, below. Taking the consistency of theoretical prediction and expert opinion at face value, it seems fair to conclude that cellphone calls (at any altitude) from fast-flying aircraft are no more likely to get through than cellphone calls from high-flying slow aircraft. A. K. Dewdney, <br> April 19th 2003 The author has not placed his university affiliations below his name, as the research described here was not conducted with any university facilities or supported by university-administered grants. He currently holds the titles of Professor Emeritus of Computer Science and Adjunct Professor of Biology at the University of Western Ontario, as well as Professor of Computer Science at the University of Waterloo.APPENDIX A: Cellphone types
APPENDIX B: LettersProfessional opinions ========================================================== Dear Sir I have yet to read the entire [Ghost Riders] article but I do have a background in telecommunications. Using a cell phone on an air craft is next to impossible. The reasons are very detailed, but basically the air craft would run major interference, as well as the towers that carry the signal would have a difficult time sending and receiving due to the speed of the air craft. As well, calling an operator? Well that is basically impossible. Having worked for both a major Canadian and American provider I had to instruct my staff that operator assistance is not an option. Have you ever tried to use a cell phone in some public buildings? Impossible. There are too many spots that service is voided. Just a tidbit of information to share. Megan Conley <megan_conley@hotmail.com> ----------------------------------------------------------------------------------- Hi, I am an RF design engineer, having built out Sprint, Verizon and another network in New Orleans. You are absolutely correct. We have trouble making these things work for cars going 55 mph on the ground. If you need another engineer's testimony for any reason, let me know I will corroborate. my engineering site: http://www.geocities.com/rf_man_cdma/ Brad Mayeux <cdmaman@engineer.com> ---------------------------------------------------------------------------------- Anecdotal evidence ========================================================== Sir, Yours is the first article I've read which focuses on those dubious 'cell phone calls'. Last month my Wife and I flew to Melbourne, about 1000 miles south of here. Cell phones are Verboten in Airliners here, but on the return journey I had a new NOKIA phone, purchased in Melbourne, and so small I almost forgot it was in my pocket. I furtively turned it on. No reception anywhere, not even over Towns or approaching Brisbane. Maybe it's different in the US, but I doubt it. There has to be an investigation into this crime. Justice for the thousands of dead and their families demands it. Best Bernie Busch <bbusch@iprimus.com.au> ----------------------------------------------------------------------------------- Hi Prof I have repeatedly tried to get my cell phone to work in an airplane above 2-3000 feet and it doesn't work. My experiments were done discreetely on [more than] 20 Southwest Airlines flights between Ontario, California and Phoenix, Arizona. My experiments match yours. Using sprint phones 3500 and 6000 models, no calls above 2500 ft [succeeded], a "no service" indicator at 5000 ft (guestimate). There seem to be two reasons. 1. the cell sites don't have enough power to reach much more than a mile, 2. The cell phone system is not able to handoff calls when the plane is going at more than 400 mph. This is simply experimental data. If any of your contacts can verify it by finding the height of the Pennsylvania plane and it's speed one can prove that the whole phone call story is forged. Rafe <rafeh@rdlabs.com> (airline pilot) ----------------------------------------------------------------------------------------- Greetings, I write in praise of your report, as I have felt from day one that the cell phone 'evidence' was perhaps the flimsiest part of the story, and am amazed that nobody has touched it until now. I'd also like to bring up the point of airspeed, which is what made the cell calls a red-flag for me in the first place. I'm not sure what your top speed achieved in the small plane was, but, in a large airliner travelling at (one would think) no less than 450mph, most cell phones wouldn't be able to transit cells fast enough to maintain a connection (at least, from what i understand of the technology) .. and we're talking 2001 cell technology besides, which in that period, was known to drop calls made from cars travelling above 70mph on the freeway (again, due to cell coverage transits) Anyway, thanks for shining the light, keep up the good work Ben Adam <email on request> ------------------------------------------------------------------------------------------- Dear Professor, Responding to your article, I'm glad somebody with authority has taken the trouble to scientifically prove the nonsense of 9/11. I was travelling between two major European cities, every weekend, when the events in the US occurred. I was specifically puzzled by the reports that numerous passengers on board the hijacked planes had long conversations with ground phone lines, using their mobile phones (and not on board satelite phones). Since I travelled every weekend, I ignored the on board safety regulations to switch off the mobile phone and out of pure curiosity left it on to see if I could make a call happen. First of all, at take off, the connection disappears quite quickly (ascending speed, lateral reception of ground stations etc.), I would estimate from 500 meters [1500 feet approx.] and above, the connection breaks. Secondly, when making the approach for landing, the descent is more gradual and the plane is travelling longer in the reach of cellphone stations, but also only below 500 meters. What I noticed was that, since the plane is travelling with high speed, the connection jumps from one cellphone station to another, never actually giving you a chance to make a phone call. (I have never experienced this behaviour over land, e.g. by car). Then, if a connection is established, it takes at least 10-30 seconds before the provider authorises a phone call in the first place. Within this time, the next cellstation is reached (travel speed still > 300KM/h) and the phone , always searching for the best connection, disconnects the current connection and tries to connect to a new station. I have done this experiment for over 18 months, ruling out weather conditions, location or coincidence. In all this time the behaviour was the same: making a phone call in a plane is unrealistic and virtually impossible. Based on this, I can support you in your findings that the official (perhaps fabricated) stories can be categorised as nonsense. With kind regards. Peter Kes <kpkes@yahoo.com> ________________________ See also Media Release 27th April 2003and Parts One and Two of the Project Achilles Report
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