Have Cell Phones Ever Worked on Airplanes?

gretavo's picture

We can learn about how cell phone technology works, for example, on wikipedia:

http://en.wikipedia.org/wiki/Cell_site

Operation

[edit] Range

The working range of a cell site - the range within which mobile devices can connect to it reliably - is not a fixed figure. It will depend on a number of factors, including

  • The frequency of signal in use (i.e. the underlying technology).
  • The transmitter's rated power.
  • The required uplink/downlink data rate of the subscriber's device [2]
  • The transmitter's size.
  • The array setup of panels may cause the transmitter to be directional or omni-directional.
  • It may also be limited by local geographical or regulatory factors and weather conditions.

Generally, in areas where there are enough cell sites to cover a wide area, the range of each one will be set to:

  • Ensure there is enough overlap for "handover" to/from other sites (moving the signal for a mobile device from one cell site to another, for those technologies that can handle it - e.g. making a GSM phone call while in a car or train).
  • Ensure that the overlap area is not too large, to minimize interference problems with other sites.

In practice, cell sites are grouped in areas of high population density, with the most potential users. Cell phone traffic through a single cell mast is limited by the mast's capacity; there is a finite number of calls or data traffic that a mast can handle at once. This limitation is another factor affecting the spacing of cell mast sites. In suburban areas, masts are commonly spaced 1–2 miles apart and in dense urban areas, masts may be as close as ¼-½ mile apart. Cell masts always reserve part of their available bandwidth for emergency calls.

The maximum range of a mast (where it is not limited by interference with other masts nearby) depends on the same circumstances. Some technologies, such as GSM, normally have a fixed maximum range of 35 kilometres (22 mi), which is imposed by technical limitations. CDMA and iDEN have no built-in limit, but the limiting factor is really the ability of a low-powered personal cell phone to transmit back to the mast. As a rough guide, based on a tall mast and flat terrain, it is possible to get between 50 to 70 km (30–45 miles). When the terrain is hilly, the maximum distance can vary from as little as 5 kilometres (3.1 mi) to 8 kilometres (5.0 mi) due to encroachment of intermediate objects into the wide center fresnel zone of the signal.[3] Depending on terrain and other circumstances, a GSM Tower can replace between 2 and 50 miles (80 km) of cabling for fixed wireless networks.[4]

[edit] Channel reuse

The concept of "maximum" range is misleading, however, in a cellular network. Cellular networks are designed to create a mass communication solution from a limited amount of channels (slices of radio frequency spectrum necessary to make one conversation) that are licensed to an operator of a cellular service. To overcome this limitation, it is necessary to repeat and reuse the same channels at different locations. Just as a car radio changes from one local station to a completely different local station with the same frequency when you travel to another city, the same radio channel gets reused on a cell mast only a few miles away. To do this, the signal of a cell mast is intentionally kept at low power and many cases tilting downward to limit its area. The area sometimes needs to be limited when a large number of people live, drive or work near a particular mast; the range of this mast has to be limited so that it covers an area small enough not to have to support more conversations than the available channels can carry. Due to the sectorized arrangement of antennas on a tower, it is possible to vary the strength and angle of each sector depending on the coverage of other towers in view of the sector.

A cellphone may not work at times, because it is too far from a mast, but it may also not work because the phone is in a location where there is interference to the cell phone signal from thick building walls, hills or other structures. The signals do not need a clear line of sight but the more interference will degrade or eliminate reception. Too many people may be trying to use the cell mast at the same time, e.g. a traffic jam or a sports event, then there will be a signal on the phone display but it is blocked from starting a new connection. The other limiting factor for cell phones is the ability of the cell phone to send a signal from its low powered battery to the mast. Some cellphones perform better than others under low power or low battery, typically due to the ability to send a good signal from the phone to the mast.

The base station controller (a central computer that specializes in making phone connections) and the intelligence of the cellphone keeps track of and allows the phone to switch from one mast to the next during conversation. As the user moves towards a mast it picks the strongest signal and releases the mast from which the signal has become weaker; that channel on that mast becomes available to another user.

[edit] Geolocation

Cellular geolocation is less precise than the GPS, but it is available to devices that do not have GPS receivers and where the GPS is not available. The precision of this system varies widely. Precision is highest where advanced forward link methods are possible (where a device is within range of at least three cell sites and where the carrier has implemented timing system use) and lowest where only a single cell site can be reached, in which case the location is only known to be within the coverage of that site. Another method using angle of arrival (AoA), possible when in range of at least two cell sites, produces intermediate precision. In the United States, for emergency calling service using location data (locally called "Enhanced 911"), it was required that at least 95% of cellular phones in use on 31 December 2005 support such service. Many carriers missed this deadline and were fined by the Federal Communications Commission.[5]

[edit] Cell phone tower power emission

 

Cell on wheels, or COW

The U.S. government agency, the FCC, says:

"For example, measurement data obtained from various sources have consistently indicated that "worst-case" ground-level power densities near typical cellular towers are on the order of 1 µW/cm2 or less (usually significantly less)." [1]

That is 0.01 Watt per square meter. There is no temptation to use more power. The entire idea of a "cell" phone system is to create small "cells" that don't interfere with each other.

The average energy received over the entire earth is about 250 Watts per square meter over a 24 hour day, ignoring clouds.[6] So, on a day with no clouds, the average electromagnetic energy received from the Sun is 25,000 times that received near a cell phone tower.

Another thing we could do is compare the alleged likely flight path (since it wasn't actually being tracked constantly) of Flight 77 and the others with the location of cell towers: http://www.gotreception.com/ 

The conclusion that we can reach quite easily after familiarizing ourselves with the way the technology works is that cell phone calls from planes were and still are impossible.  We of course would never advocate breaking the law and trying it yourself on your next flight, but if you were to forget to turn your phone off before take-off and remembered as your plane was ascending, you might try looking at the signal strength your phone has when you turn it off.  If you're still over a metropolitan are you might have a bar or two, but if you happen to be somewhere over west virginia or the Appalachians, well I suspect you'd be out of luck...

Never fear, however, as Eirk Larson aka Loose Nuke suggests that the perpetrators would have of course wanted the doomed passengers to make those calls, so they would have prepared all the planes in advance with cell phone repeaters!

 

Second, self-powered cell phone repeaters may have been placed on board the planes to ensure that calls would reliably connect. A repeater is "sufficiently powerful to establish reliable connections with ground stations for several minutes at a time, and forwards all the communications between the cell phones aboard the plane and ground stations." Cell phone calls from planes were possible before 2001, but it’s obvious that reception quality and the ability to connect and maintain a quality connection would decrease at higher altitudes and speeds. Some of the reported cell phone calls did take place at lower altitudes, but other reported calls, including Tom Burnett’s, were at higher altitudes.

It could easily have been anticipated by insiders arranging for planes to be successfully hijacked and hit their targets on 9/11, that passengers, once aware of the hijackings, would attempt to use their cell phones and report hijackings by Middle-Eastern-looking men. It would have been obvious that news reports of these calls would be emotionally-charged, and could be used to convince the public that Islamic radicals were responsible for 9/11, as well as channel the public’s fear and anger into support for a ‘war on terror’. Certainly, the calls were used in exactly this way. If repeaters were involved (no direct evidence has surfaced), this would create a different set of problems for the official 9/11 conspiracy theory, and the need to cover this up could explain why the FBI has denied that certain calls were made by cell phone.

In effect, it seems that pouncing on DRG over his speculation about the use of voice-morphing distracts from the more simple question of "were the cell phone calls even remotely possible" the answer to which is "no, they were not."  Just as we don't need to prove how the demolitions of the twin towers and building 7 were carried out to show that the official explanation is impossible, we don't have to prove anything about the cell phone calls beyond that they were impossible, leaving only the question, for future investigations, of either how the alleged victims' families were duped OR whether they were willing participants in a despicable fraud.