So there's a chance at 20,000 feet? Not impossible?
What about at about 6,000 feet?
cant be done.read these testimonys.but again expert testimonsy means nothing to you right so what bother?
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>
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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 engineerÂ’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>
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Anecdotal evidence
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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 itÂ’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>
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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 donÂ’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 itÂ’s speed one can prove that the whole phone call story is forged.
Rafe <rafeh@rdlabs.com> (airline pilot)
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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.
IÂ’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. IÂ’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 wouldnÂ’t be able to transit cells fast enough to maintain a connection (at least, from what i understand of the technology) .. and weÂ’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
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Dear Professor,
Responding to your article, IÂ’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>
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It must be clearly understood that Prof. DewdneyÂ’s tests were conducted in
slow-moving (<150kts) light aircraft at relatively low altitudes (<9000ft
AGL). The aircraft from which the alleged calls were made on 9/11 were
flying at over 30,000 ft at speeds of over 500 MPH.
During a recent round-trip flight from Orange County, CA to Miami, FL (via
Phoenix, AZ), I, personally conducted an unofficial “test” using a brand new
Nokia 6101 cellular phone [NB: 2005 technology]. En route, I attempted
(discretely, of course) a total of 37 calls from varying altitudes/speeds. I
flew aboard three types of aircraft: Boeing 757, 737, and Airbus 320. Our
cruising altitudes ranged from 31-33,000ft, and our cruising speeds, from
509-521 MPH (verified post-flight by the captains). My tests began
immediately following take-off. Since there was obviously no point in taking
along the wrist altimeter I use for ultralight flying for reference in a
pressurized cabin, I could only estimate (from experience) the various
altitudes at which I made my attempts.
Of the 37 calls attempted, I managed to make only 4 connections - and every
one of these was made on final approach, less than 2 minutes before flare,
I.e., at less than 2,000ft AGL.
Approach speeds varied from 130-160 kts (Vref, outer marker), with flap and
gear extension at around 2,000ft (again, all speeds verified by flightdeck
crews). Further, I personally spoke briefly with the captains of all four
flights: I discovered that in their entire flying careers, NOT ONE of these
men had EVER been successful in making a cell phone call from cruising
altitude/speed in a variety of aircraft types. [NB: Rest assured the
ubiquitous warnings to “turn off all electronics during flight” are
completely unfounded. All modern aircraft systems are fully shielded from
all forms of RF/EMF interference (save EMP, of course). This requirement was
mandated by the FAA many years ago purely as a precautionary measure while
emerging advanced avionics systems were being flight tested. There is not a
single recorded incident of interference adversely affecting the performance
of airborne avionics systems.]
Obviously, my casual, seat-of-the-pants attempt at verifying a commonly
known fact can hardly be passed off as a “scientific” test. Ergo, I shall
offer Prof. Dewdney¹s conclusion, excerpted from his meticulously detailed
and documented paper re slow-flying light aircraft at low altitudes.
Nila Sagadevan
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Prof. Dewdney:
I do not pretend to be any sort of expert of cellular communications, but I am an electronics engineer and hold both amateur and commercial FCC licenses, so I do have some understanding of the relevant principles of radio communication systems.
I read with interest your analysis of terrestrial contact probabilities via cellphones from aircraft. I believe your conclusions are sound, but would like to comment on an element which you pondered regarding the sort of apparent discontinuity in what seems otherwise to be an inverse-square relation beyond a certain altitude.
Cellphones operate by Frequency Modulation, and as such the (apparent) signal strength is not discernible to the listener because the intelligence is contained only in the frequency and phase information of the signal before demodulation. Hence, the system works pretty well until it is so weak that it is abruptly lost. That is, the system can no longer “capture” the signal. It does not get louder and softer with signal strength -until the signal is below the detection level of the receiver, at which point it is essentially disappears. The cellphone also adjusts the transmit power according to the signal level received at the tower end of the link. Once it is at maximum output, if the signal diminishes beyond some minimum threshold depending on the receiver design, it is lost altogether and not simply degraded in quality. Analogous behavior is experienced with FM broadcast stations; as you travel away from the transmitter the station is received with good fidelity until at some distance it rather suddenly cannot even be received any longer at all.
Additionally, cellphone towers are certainly not optimally designed for skyward radiation patterns. Since almost all subscribers are terrestrial that is where the energy is directed, at low angles.
In summary, if your observed discontinuous behavior is real, and I believe there is technical reasoning for such, the probability of making calls beyond some threshold altitude is not simply predictably less, but truly impossible with conventional cellphones under any condition of aircraft etc. because of the theoretical limits of noise floor in the receiving systems. I think the plausibility of completing the calls from 30,000+ ft. is even much lower than might be expected from extrapolations of behavior at lower altitudes which you investigated.
Thank you for your thoughtful work in this area.
Sincerely,
Kevin L. Barton
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Dear Dr Dewdney
I too can verify that on a private charter airline, Champion Air, which was a 737-300, I believe that is correct or it might have been a 727-300. But regardless of that, we took off from Dallas/Ft. Worth International Airport at 0735 in July of 2003. As we were taxiing to the run way the pilot told us to please turn off all electronic equipment, i.e. Cell Phones, Laptops, etc. I did so, but shortly after take off and before the pilot said we could use our “electronic equipment” I thought I would call my mom and let her know we were in the air. We had not been off the ground for more than 2 minutes. I would guess between 2000 and 5000 ft. I was using at the time one of Motorola’s top of the line phones, a V60t. My cell phone carrier is Cingular which is quite a widespread carrier as you probably know, I had absolutely no signal at all. Since we were flying to Cozumel, Mexico I kept trying and watching for a signal until we got out past the coast line of Texas, when then I knew for sure I wouldn’t get a signal again until we landed in Cozumel. Again in June 2004 we flew out of DFW, same airline, same type of plane, and the same thing occurred. This time I left my phone on from take off and up until it lost the signal. Again we couldn’t have been more than 2000 to 3000 ft. off the ground. I lost the signal and never again got a signal until the plane landed in Cozumel. I find it highly unlikely that anyone could have used a cell phone on 9/11/01 at above 2000 feet.
Sincerely,
Brad Taylor
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IÂ’ve been using Nokia phones with automatic nationwide roaming, and Cingular before it was Cingular and long before 9/11. I confess to having turned my cell phone on while flying commercial airlines several times prior to 9/11, just to see if signals were available. At 2,000 feet the phone went totally flat. No calls out or in were ever possible. Of course all these stories are anecdotal, but according to cell phone engineers who have cared to comment have stated that commercial aircraft fly far too fast and far too high to expect that folks on flight 93 ever managed to get a call out on their own phones. TheyÂ’ve said that the towers canÂ’t transition or hand over private cell phones fast enough. I hope we can hear from other ATPs on this subject.
George Nelson (Col. USAF ret.)
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