Latest revision as of 08:41, 9 July 2012
Ask most people how we know the 9/11 flights were hijacked, and they'll tell you about the phone calls from passengers and flight attendants, the talk of stabbings, mace, bomb threats, and more. But not everyone accepts these calls as genuine. One commonly repeated claim is that cellphone calls above 8,000 feet were essentially impossible, for instance, as David Ray Griffin explains:
The “impossible” claim is most often associated with Professor AK Dewdney, in a study of his own called "Project Achilles". He actually tried making calls at various altitudes, and concluded that "cellphone calls from passenger aircraft are physically impossible above 8000 feet and and statistically unlikely below it". There are reasons to question Dewdney’s conclusions, though. Read more here.
And if you read the Griffin quote carefully, you'll find another important qualification in the mention of airphones. These are seatback phones designed to work at altitude, and testimony at the Moussaoui trial explained that the vast majority of Flight 93 calls (this flight had more calls than any other) were made this way. The list was Lauren Grandcolas (airphone); Mark Bingham (airphone); Joseph DeLuca (airphone); Linda Gronlund (airphone); Jeremy Glick (airphone); Todd Beamer (airphone); Sandra Bradshaw (airphone); Thomas Burnett Jr (airphone and probable cellphone); CeeCee Lyles (airphone and cellphone); Marion Britton (airphone); Honor Wainio (airphone); Waleska Martinez (airphone); Ed Felt (cellphone) (Source). There's no dispute that airphones would have been able to work on 9/11, which only leaves us with a very few calls that can be regarded as "suspicious".
Still, it could be argued that you need only show one call was impossible to expose the truth, so it's worth considering the issue in more detail. Exactly what sort of range can you expect to achieve with a mobile? In principle the distances look impressive:
22 miles would be over 100,000 feet. You can’t apply such a simple rule, though, because mobile networks aren’t designed to serve the skies. Others use this quote as an example of professional scepticism.
Although the full quote tells a slightly different story.
Below a certain altitude? What might that be?
So it may work at 30,000 feet, although only momentarily? Apparently the New York Times agrees:
Note particularly the point that “some older phones” may work at twice the altitude of newer digital systems, up to 50,000 feet. Were any of those in use on 9/11? We don’t know, but it’s worth considering before you suggest the calls were “impossible”.
This question has also been addressed in The Hindu:
QUESTION: Can we receive a mobile signal while travelling in an aeroplane?
ANSWER : Mobile phones can receive signals while travelling in an aircraft, provided the base station range allows. Territory covered with GSM network is divided into hexagonal cells. The covering diameter of each hexagonal cell may be from 400 m up to 50 km, which consists of base station that provides communication-receive and transmission, and antennae.
All GSM cellular communication telephone cells are performed via these antennae and stations, which are regulated by switching centre. Switching centre provides communication between city telephone network, base stations and other cellular communication operators. Every time you switch on your cell phone, the communication is performed with the nearest base station. Hence it is possible to receive signals on cell phone while travelling in an aeroplane, provided the base station range allows.
Cell phone use during flights is still banned by regulations because it disrupts cell service on the ground and have the potential to interfere with an airplane's navigation and communication instruments.
In theory, any device that emits electronic waves — including cell phones, laptops, electronic games, pacemakers and hearing aids — has the potential to cause interference to an aeroplane.
To be safe, it is recommended banning all electronics during critical phases of a flight, which are generally considered to be during takeoff and landing, when a plane is below 10, 000 feet.
From high in the sky, a cell phone acts like a sponge, sucking capacity out of the cellular sites that carry calls. For ground users, cell phones communicate by connecting to one cell site at a time, from the air, because of the height and speed of an aircraft, the phones often make contact with several sites at once.
If allowed this would limit call capacity, which could mean less revenue. The cellular signal from the air is also especially strong, since it is unimpeded by buildings or other ground clutter. That often means it can jump on a frequency already in use on the ground, causing interruptions or hang-ups.
And airborne cellular calls are sometimes free because the signal is moving so fast between the cells that the software on the ground has difficulty, recording the call made, put the plane at risk because cellular phones can disrupt the aeroplane's automatic pilot, cabin-pressure controls.
Modern aircrafts are installed with in-flight telephones mounted on passenger seats. The carriers receive a cut of the revenue from the telephones installed onboard.
They charge about about $6 for a one minute call, more than 20 times typical cell-phone rates. Thus the airlines and telecommunications companies also have an economic incentive to keep cell phones turned off in the air.
These in-flight telephones also operate on the cellular technology — using a single airplane antenna to which the onboard phones are typically wired.
The outside aircraft antenna that carries the air-phone calls also connects to a ground-based cellular network — but with cells that are spaced much farther apart to avoid multiple phone-ground links.
http://www.hindu.com/seta/2003/10/31/stories/2003103100110300.htm
And in Wireless Week:
Making Calls From The Air
By Brad Smith
September 24, 2001
c 2003, Reed Business Information, a division of Reed Elsevier Inc. All Rights Reserved.
When several passengers aboard the hijacked airliners made calls to family and spouses from their wireless phones on the now-infamous Sept. 11, it came as a surprise to many that the calls actually were completed.
Although airline passengers are warned against using their mobile phones in flight, it's fairly well-known that private airplane pilots often use regular cellular and PCS phones, even if it is illegal. Not quite as well-known, however, is that people have used their wireless phones to make surreptitious calls from the bathrooms of airliners.
The technology is there to support such airborne mobile connections. Take the Colorado company Aircell Inc., which uses FCC-approved equipment for wireless phone service.
But how does a terrestrial technology work in the sky?
First, altitude in itself is not a problem. Earthbound wireless phones can talk to base stations up to 10 miles away, depending on the terrain, while a typical passenger jet flies at an altitude of about six and a half miles. Since cell site antennas are configured to pick up signals horizontally and not from overhead, performance is usually compromised in calls from above. Nevertheless, cell sites can pick up signals from the air from great distances.
Toby Seay, vice president of national field operations for AT&T Wireless, says the technological limits to using a cell phone aboard a plane include the signal strength, potential signal inhibitors and "free space loss" as the signal gradually loses strength. The frequency used can make a difference, too. A signal using an 800 MHz cellular frequency can travel farther than a 1900 MHz PCS signal because of the different propagation characteristics of the two wavelengths.
The biggest problem with a phone signal sent from the air is that it can reach several different cell sites simultaneously. The signal can interfere with callers already using that frequency, and because there is no way for one cell site to hand off calls to another that is not adjacent to it, signals can become scrambled in the process. That's why wireless calls from jetliners don't last long, says Kathryn Condello, vice president of industry operations for CTIA. The network keeps dropping the calls, even if they are re-established later.
The phones on the back of the seats in most airplanes work similarly to a regular wireless phone. The major differences are that the antennas at the ground base stations are set up to pick up the signals from the sky, and there are far fewer stations handing off signals from one to another as a plane crosses overhead.
Also, Seay says, the airplane phones operated by AT&T Wireless and the GTE subsidiary of Verizon Communications send signals through wires to an antenna mounted on the outside of the plane. That is done to prevent interference with the plane's own radio communications, as well as to eliminate signal loss caused by the airplane's metal fuselage.
www.wirelessweek.com/index.asp?layout=story&articleId=CA160201&stt=001 (Original URL, now dead)
Then there’s also this report about an FCC study, talking about mobile use “at high altitude”:
John Sheehan, who headed a study into the supposed effects of mobile use on aircraft systems, says mobiles are used on planes "thousands of times every day", that he regularly uses a mobile in the sky himself, and that they could be allowed to be used above 10,000 feet - why would he say that, if he believed this wasn't possible?
And Popular Mechanics' "Debunking 9/11 Myths" quoted a couple of industry figures who accepted that calls at altitude were possible:
While not exactly reliable, cell-phone calls from airplanes were possible in 2001-even from extremely high altitudes. "Because cell sites have a range of several miles, even at 35,000 feet, that's entirely possible," says Rick Kemper, director of technology and security at the CTIA-The Wireless Association. "It's not a very good connection, and it changes a lot, and you end up getting a lot of dropped calls because you're moving through cell sites so fast."
Paul Guckian, vice president of engineering for cell-phone maker Qualcomm, concurs. "I would say that at the altitude for commercial airliners, around 30,000 or 35,000 feet, [some] phones would still get a signal," he tells Popular Mechanics. "At some point above that-I would estimate in the 50,000-foot range-you would lose the signal." Flight 93 never flew higher than 40,700 feet.
Page 83/ 84, Debunking 9/11 Myths, Popular Mechanics
Backing up these claims are further reports about people using their phones in flight. These are stories from 9/11:
This guy was arrested and jailed for preparing to send a text message at 31,000 feet (don’t know if he did or not, but if there was no signal you’d have expected him to turn it off as requested):
Here’s a pilot calling his wife, perhaps from 15,000 feet:
And there are various anecdotal reports, which prove nothing in themselves, but we find it hard to believe that they’re all fictional.
IEEE Spectrum even ran a test to check this, and discovered cellphones were being used within commercial aircraft cabins (and not just while taking off or landing, where altitudes will be lower):
Sceptics still point to the case of Tom Burnett. His wife says she recognised his caller ID for the first call, and we know the times she says these were made:
The NTSB Flight Data Recorder report tells us about the altitude around these times:
United flight 93... reached its assigned cruising altitude of 35,000 feet at about 9:02 am. The flight appears normal until a brief descent of around 600 feet starting at 9:28. The words "get out of here" and sounds of a struggle were recorded on the air traffic control radio at FAA's Cleveland Center facility at this time... At 9:34 the airplane starts to climb from 35,000 feet... The airplane maintained a maximum altitude of 41,000 feet for about two minutes and then started descending at about 9:39...
There was a brief interruption in the descent at 9:46 as the airplane climbed from 19,000 to 20,500 feet before resuming its descent, but at a slower rate... At about 9:59 the plane was at 5,000 feet...
How were the calls made? Jere Longman's Among the Heroes tells us about the first three:
We have two cell phone calls according to Longman, then, a quick ten seconds at 35,000 feet, and a longer one at around 20,000 feet. It's plainly not easy to connect at the higher altitude, otherwise more would have done so, but we don't believe it's been shown to be at all implausible. We've already referenced several articles suggesting it may well be possible to successfully connect at these altitudes, especially for a very brief call.
One argument against the use of airphones involves pointing to press reports specifically saying that a mobile was used. Here's an example:
"At around the same time, the hijackers on flight 175 had taken control. Five minutes later, Peter Hanson, 32, a software executive travelling with his wife and two-year-old daughter, telephoned his parents in Connecticut on his mobile. Hurriedly he told the elderly couple of the knifings and the hijacking".
www.telegraph.co.uk/news/main.jhtml?xml=/news/2001/09/16/watt16.xml
The problem with relying on a story like this is we don't know if the reporter verified it. Did he really try to find out whether Hanson used a mobile, or an Airfone? We don't think so, because it makes no difference to the story he's telling at all. And a sentence later in the same story confirms this:
"Those with no mobiles could only pray silently".
Whoever wrote this clearly didn't know that the planes had Airfones, and simply assumed any calls were made from mobiles instead. And the author's assumptions are evidence of nothing at all.
Other articles simply use terms like “cell phone” incorrectly. Here’s a graphic from the Post Gazette, for instance.
Take a look at point #12, where it’s suggested that Beamer made a “cell phone call”. Where’s the evidence for that, especially as we know he spoke to an Airfone operator? Looks to us like this is simply wrong, and another example of how reports use terms like “mobile” and “cell phone” for convenience, without verifying whether they were true.
Inconsistencies elsewhere are easy to find. One Flight 93 article tells us this:
"In the opposite lavatory, Jeremy Glick, an internet company worker from Hewitt, New Jersey, telephoned Lyzbeth, his wife, on his mobile".
www.telegraph.co.uk/news/main.jhtml?xml=/news/2001/09/16/watt16.xml
He was in the lavatory and so must have used a mobile. However, look elsewhere and we find:
"Jeremy Glick, 31, used a GTE Airfone to call his wife from Flight 93".
www.post-gazette.com/nation/20020911glick911p6.asp
So maybe not.
And not all mobile calls are automatically suspect.
"At 9.58am a 911 call - the last mobile phone contact from Flight 93 - was made from one of the airliner's toilets by passenger Edward Felt.
Glenn Cramer, the emergency supervisor who answered it, said on the day: "He was very distraught. He said he believed the plane was going down".
www.mirror.co.uk/news/allnews/page.cfm?objectid=12192317&method=full&siteid=50143
No reason to believe this wasn't a mobile call, but it was only minutes before the crash, and other reports suggest the plane was very low:
"Minutes before the crash, Eric Peterson of Lambertville, Pennsylvania, saw the 757 flying extremely low, maybe 300 feet from the ground".
www.pathlights.com/Flight%2093.htm
No altitude issues here.
None of this is 100% conclusive, but it does illustrate the point: there’s plenty of support for the idea cellphone calls can be made from altitude, and the Airfones were available for everyone else. Overall we see no compelling reason to believe the calls weren't genuine.