Mobile phones on aircraft - AbsoluteAstronomy.com

As of 2011, most airlines do not allow the use of mobile phones on aircraft, because it is thought they could adversely affect the navigational instruments in the cockpit

Cockpit

A cockpit or flight deck is the area, usually near the front of an aircraft, from which a pilot controls the aircraft. Most modern cockpits are enclosed, except on some small aircraft, and cockpits on large airliners are also physically separated from the cabin...

. Because of this, the airline personnel require that such devices be turned off while the aircraft is airborne.

In the US, the use of mobile phones and similar devices on airplanes has been banned by the governmental Federal Communications Commission

Federal Communications Commission

The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...

.

There is evidence showing various degrees of correlation between use of mobile phones in flight and various instrument problems. One study concluded that mobile phones used in the cabin could exceed the rated allowable interference levels for some avionics installed in aircraft. On the other hand, links between device use and actual system failures have not been proven, nor have the reported incidents been reproduced in ground tests.

Since the regulations were imposed by various international bodies, there have been advances in equipment and systems which have allowed the gradual introduction of safe in-flight communications via mobile phones and such devices. These systems are being implemented by an increasing number of airlines and carriers as each is tested by the authority responsible for air-safety and deemed to be fit for use.

Electromagnetic interference

Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...

to aircraft systems is theoretically possible from active radio transmitters such as mobile phones, small walkie–talkies or radio remote–controlled toys and also from unintentional emitters such as ordinary radio receivers, computers and virtually any non–trivial electronic device. However, there has been little empirical support of this theory and studies have either been non-conclusive or found that there is no evidence that the use of electronic devices on airplanes could interfere with an aircraft's systems.

There are some reports that indicate this and some that refute it:

Boeing

Boeing

The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...

performed extensive tests as reported in AeroMagazine's Interference from Electronic Devices in response to reports by flight crews of anomalies that they believed to be caused by electronic devices. The flight crews had apparently confirmed the effect by switching the "suspect" devices on and off and watching the effects. Despite this and despite the fact that Boeing in many cases was able to purchase the actual offending device from the passenger and use it in extensive testing Boeing was never able to reproduce any of the anomalies. The report concludes:
ABC News

ABC News

ABC News is the news gathering and broadcasting division of American broadcast television network ABC, a subsidiary of The Walt Disney Company...

20/20 aired a report in December 2007 trying to get to the bottom of the ban on cell phone usage in aircraft. They interviewed one of the authors of the IEEE Spectrum

IEEE Spectrum

IEEE Spectrum is a magazine edited by the Institute of Electrical and Electronics Engineers. The IEEE's description of it is:IEEE Spectrum began publishing in January 1964 as a successor to Electrical Engineering...

report cited below but also noted that this study was not designed to actually detect interference–only that cellphones which are not switched off. The report concludes that the primary reason for the ban on cell phone use in flight is that neither the FAA nor the FCC are willing to spend the money to perform conclusive safety tests. They have left this up to the airlines who do not see any return on investment made in paying for such tests. According to the 20/20 website ABC News

ABC News

ABC News is the news gathering and broadcasting division of American broadcast television network ABC, a subsidiary of The Walt Disney Company...

consultant and veteran airline pilot John J. Nance

John J. Nance

John J. Nance is an American pilot, aviation safety expert, and author. His novels are largely about aviation, while his non-fiction covers various other areas.-Biography:Nance was born in Dallas, Texas...

states categorically:
A NASA publication details the fifty most recent reports to the Aviation Safety Reporting System

Aviation Safety Reporting System

The Aviation Safety Reporting System, or ASRS, is the US Federal Aviation Administration's voluntary system that allows pilots and other airplane crew members to confidentially report near misses and close calls in the interest of improving air safety...

(ASRS) regarding "avionics problems that may result from the influence of passenger electronic devices." The nature of these reports varies widely. Some merely describe passengers' interactions with flight crews when asked to stop using an electronic device. Other reports amount to crews reporting an anomaly experienced at the same time a passenger was witnessed using a mobile phone which indicates only a weak correlation and not causality. However a few reports state that anomalies were observed to appear and disappear as the suspect device was turned on and off which would indicate a high degree of correlation.

A NASA report from 2001 summarizes "14 years of incidents reported by pilots to the ASRS" of interference caused, or suspected to be caused, by passengers' electronic devices. Mobile phones were the most frequently identified source of interference with laptop computers a close second. In no cases were the affected avionics found to be defective upon later testing. Degrees of correlation or confidence were not among the data summarized in the report.

A 2003 study involved three months of testing with RF spectrum analyzers and other instruments aboard regular commercial flights. The report found that on a typical flight at least one mobile phone is likely to be left on throughout the flight and that a mobile phone in use produces a far stronger signal than one that is simply left switched on. In the authors' words:
A 2000 study by the British Civil Aviation Authority

Civil Aviation Authority

This is a list of national and supra-national civil aviation authorities.-See also:* Air route authority between the United States and the People's Republic of China* National Transportation Safety Board -External links:****...

concluded that:
A report from BBC

BBC

The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

news comments that "most of the evidence is circumstantial and anecdotal. There is no absolute proof mobile phones are hazardous." It also quotes Dan Hawkes the head of avionic systems at the Civil Aviation Authority (CAA):
Whether interference from small battery-powered devices should have any influence on electronic systems that should be designed to fly through lightning storms without failing is often disputed by critics of the ban. An article by Tekla S. Perry and Linda Geppert, then editors of IEEE Spectrum, offers an explanation: "While a brand new aircraft may indeed be completely immune from such interference, shielding and other mechanisms that normally protect the avionics do degrade over time, after thousands of takeoffs, landings, and pressurization cycles and various maintenance procedures. Similarly, the shielding in passengers' devices also degrades due to the passage of time and, in some cases, repair procedures."

Conclusions

The cost of an accident, should one occur, could be extremely high in terms of human life and the risk is completely avoidable in that no one absolutely needs to use their mobile phone in flight. The regulatory agencies and aviation industry take the position that any increased risk is unacceptable if it is avoidable.

Some mobile phone systems such as GSM may cause an irritating buzz, which could disrupt communications from the pilot to ground. The high speed of air travel may make interference more likely than it would otherwise be. The maximum speed of travel in a mobile phone system is limited by several factors; frequency changes, rate of change of timing offset, etc. and the speed of an airplane often exceeds these as, typically, mobile phones are designed for use in a fast car which means the phone will fail to register to the network and retry registration repeatedly.

Social resistance to mobile phone use on flights

Some people may prefer a ban on mobile phone use in flight as it prevents undue amounts of noise from cellphone chatter. AT&T has suggested that in-flight mobile phone restrictions should remain in place in the interests of reducing the nuisance to other passengers caused by someone talking loudly on a phone next to them.

Competition for airlines' in-flight phone service

Skeptics of the ban have suggested that the airlines support the ban because they do not want passengers to have an alternative to the in-flight phone service such as GTE's Airphone. Andy Plews a spokesman for UAL's United Airlines was quoted as saying "We don't believe it's a good safety issue"..."We'd like people to use the air phones." Such services are much more expensive than mobile phone services and provide slow data rates at a similarly high price. In general the airlines have had little success in selling these services and the in-flight phone equipment has disappeared from most U.S. domestic flights.

Emirates Airline

On 20 March 2008, Emirates Airline

Emirates Airline

Emirates is the airline based in the Emirate of Dubai part of the United Arab Emirates . Based at Dubai International Airport it is the largest airline in the Middle East, operating over 2,400 flights per week, from its hub at Terminal 3, to 111 cities in 62 countries across six continents...

flights began allowing in-flight voice calls on some commercial airline flights.

The approval by EASA of these systems has established that GSM phones on certified aircraft types are considered safe to use when installed with an on-board cellular picocell

Picocell

A picocell is a small cellular basestation typically covering a small area, such as in-building , or more recently in-aircraft...

Europe

AeroMobile

AeroMobile was established as a joint venture between ARINC and Telenor in 2006 and since January 2010, AeroMobile is a wholly owned subsidiary of Telenor...

and OnAir

OnAir

Incorporated in February 2005, OnAir is a joint venture with SITA and Airbus. OnAir is headquartered in Geneva, Switzerland, and has operations in Seattle and Montreal and sales offices in London, Kuala Lumpur and Dubai....

allow the use of personal electronics devices aboard flights. The services are most prevalent in Europe and are licensed to specific airlines for use.

Malaysia Airlines

Malaysian Airline System Berhad , DBA Malaysia Airlines , is the government-owned flag carrier of Malaysia. Malaysia Airlines operates flights from its home base, Kuala Lumpur International Airport, and its eastern hub in Kota Kinabalu. It has its headquarters on the grounds of Sultan Abdul Aziz...

flights are installed with AeroMobile systems to enable in flight voice calls and text messages.

Mobile phones on corporate jets

Falcon 2000 on 2 April 2009 implemented a new concept designated SafeCell when it commenced flying.

United States

To prevent disruption to the cell phone network from the effects of fast-moving cell phones at altitude (see discussion below), the FCC has banned the use of cell phones on all aircraft in flight. The FCC did, however, allocate spectra in the 450 MHz and 800 MHz frequency bands for use by equipment designed and tested as "safe for air-to-ground service" and these systems use widely separated ground stations. In the 450 MHz band co-channel assignments are at least 497 miles apart and in the 800 MHz band only specific sites were authorized by the FCC. The 450 MHz service is limited to "general aviation" users, in corporate jets mostly, while the 800 MHz spectrum can be used by airliners as well as for general aviation. The 450 MHz spectrum is named AGRAS while the 800 MHz service is under review following an auction of the spectrum in 2006.

Regulations and practices

Mobile phones are portable electronic devices and, as such, are banned from use in civilian airplanes by the Federal Aviation Agency unless the operator of a commercial aircraft or pilot of a private aircraft determines that it could not cause interference to avionics in the aircraft.

The FAA in 14 C.F.R § 91.21 bans the use of all portable electronic devices (with a few odd exceptions) for all flights operated by an airline or those flights under Instrument flight rules

Instrument flight rules

Instrument flight rules are one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other are visual flight rules ....

(IFR). It does allow that the airline (or for privately operated aircraft the pilot) can make an exception to this rule if the operator deems that device safe. This effectively gives the airline, or pilot, the final word as to what devices may be used aboard an aircraft as far as the FAA is concerned although the FCC restriction still applies.

Note that for aircraft operated by an airline the pilot is not considered the "operator" and cannot legally allow exceptions to the airline's restrictions although the pilot may dictate additional restrictions.

No U.S. airlines have approved the use of mobile phones while in flight.

The FAA in Advisory Circular 91.21-1A recommends that aircraft operators blanket ban all intentional transmitters and mentions specifically CB radios, remote control devices and cellular phones. While Advisory Circulars are not legally binding air carriers rarely ignore the official written advice from the FAA.

This Advisory Circular has since been superseded by AC 91.21.1B.

Federal Aviation Regulation (FAR) 91.21 states that the Pilot In Command of an aircraft that is NOT IFR, and NOT Part 121 (Commercial Air Carriers), can allow usage of "Portable Electronic Devices". However to take the attitude that "The FAA doesn't say I can't do it" is incorrect, particularly in the category of radiotelephone communications governed by the FCC. FCC regulations, and specifically Title 47 Part 22.925 (Oct 1, 2006 revision), states "Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not be operated while such aircraft are airborne (not touching the ground). When an aircraft leaves the ground, all cellular telephones on board that aircraft must be turned off.".

The use of cell phones aboard airborne planes is banned by the FCC in 47 C.F.R. § 22.925: "The use of cellular telephones while this aircraft is airborne is prohibited by FCC rules.... The use of cellular telephones while this aircraft is on the ground is subject to FAA regulations." This ban applies to phones that use the 800 MHz spectrum. Personal Communications Services (PCS) phones that use the 1900 MHz spectrum are governed under FCC 47CFR24 and their use in aircraft is not restricted by the FCC whether on the ground or in flight.

Cell tower channel re-use

The U.S. Federal Communications Commission

Federal Communications Commission

(FCC) currently prohibits the use of mobile telephones aboard any aircraft in flight. The reason given is that mobile phone systems depend on channel reuse and operating a phone at altitude may violate the fundamental assumptions that allow channel reuse to work.

The FCC is also concerned that the use, or even non-use, of a powered cell phone could cause disruption to the cell systems' towers and has banned their use.

Mobile telephones are intentionally designed with a low power output. A tower is the center of a "cell" and due to attenuation with distance (inverse square law) cell phone transmissions can usually be received only weakly by towers in adjacent cells and not at all in cells farther away (non-adjacent cells). This allows the channel used by any given phone to be reused by other phones in non-adjacent cells. This principle allows tens or hundreds of thousands of people to use their phones at the same time in a given metropolitan area while using only a limited number of channels.

Channel reuse works because a mobile phone on the ground will only have one "closest" tower that can possibly use a particular group of frequencies, CDMA codes, or time slots. The software that manages the system assumes that the signal from a phone on a particular tower can, on other towers, only be "heard" at greatly reduced signal strength. The frequency, code, or time slot used by the phone can therefore be reused by other phones on other towers.

In the old analog cell system a channel was simply a frequency pair: There were seven groups of 35 channels each and no two adjacent cells used the same channel groups. Modern CDMA and TDMA

Time division multiple access

Time division multiple access is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This...

systems are more complex: A channel in TDMA is a frequency pair, and a time slot, and a channel in CDMA is a spread spectrum key but the principle of channel reuse still applies.

If a mobile phone is operated from an aircraft in flight above a city these assumptions are no longer valid because the towers of numerous different cells may be about equidistant from the phone. Multiple towers might assume that the phone is under their control and the phone could be assigned a free channel by one tower but could also be heard on other towers using the same channel group. The channel might already be in use on those other towers and could cause interference with existing calls. It is also possible that the software controlling the towers could crash. Even if the software can cope with hearing the same phone on multiple non-adjacent towers the result at best is an overall decrease in system capacity.

An additional concern is the output power of the mobile handset. Because the towers might be miles below the aircraft the phone might have to transmit at its maximum power to be received. This will increase the risk of interference with electronic equipment on the aircraft.

In flight technology

Airlines have installed technologies to allow phones to be connected within the airplane as it flies. Such systems were tested on flying scheduled flights from 2006 and in 2008 several airlines started to allow in-flight use of mobile phones. These changes have been attributed to strong demand by frequent fliers. A few airlines that are installing the equipment are also considering the issue of "phone-free zones" and "quiet time" on long flights.

Future changes

A few U.S. airlines have announced plans to allow mobile phones to be used on aircraft pending approval by the FCC and the FAA. The method is similar to that used in some cars on the German ICE

InterCityExpress

The Intercity-Express or ICE is a system of high-speed trains predominantly running in Germany and neighbouring countries. It is the highest service category offered by DB Fernverkehr and is the flagship of Deutsche Bahn...

train and the aircraft will contain a device known as a picocell

Picocell

A picocell is a small cellular basestation typically covering a small area, such as in-building , or more recently in-aircraft...

. The picocell will act as a miniature mobile telephone tower communicating with mobile phones within the aircraft and relaying the signals to either satellites or a terrestrial-based system. The picocell will be designed and maintained for full compatibility with the rest of the on-board avionics. Communication between the picocell and the rest of the telephone network will be on separate frequencies that do not interfere with either the cellular system or the aircraft's avionics much like the on–board phone systems already aboard many commercial aircraft. Since the picocell's antennas within the aircraft would be very close to the passengers and inside the aircraft's metal shell both the picocell's and the phones' output power could be reduced to very low levels reducing the chance for interference. Such systems have been tested on a few flights within the United States under a waiver from the FCC.

ARINC and Telenor have formed a joint venture company to offer such a service on board commercial aircraft. The mobile phone calls are routed via satellite to the ground network and an on-board EMI screening system stops the cellphones contacting the ground network.

These systems are comparatively easy to implement for customers in most of the world where GSM phones operating on either of just two bands are the norm. The multitude of incompatible mobile phone systems in the United States and other countries makes the situation more difficult — it is not clear if the onboard repeaters will be compatible with all of the different cell-phone protocols (TDMA

Digital AMPS

IS-54 and IS-136 are second-generation mobile phone systems, known as Digital AMPS . It was once prevalent throughout the Americas, particularly in the United States and Canada. D-AMPS is considered end-of-life, and existing networks have mostly been replaced by GSM/GPRS or CDMA2000...

, GSM, CDMA, iDen

Integrated Digital Enhanced Network

Integrated Digital Enhanced Network is a mobile telecommunications technology, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone...

) and their respective providers.

On 30 August 2006 the Irish airline Ryanair

Ryanair

Ryanair is an Irish low-cost airline. Its head office is at Dublin Airport and its primary operational bases at Dublin Airport and London Stansted Airport....

announced it will introduce a facility to allow passengers to use their mobile phones in-flight. This service as started on the 19th February 2009 with 20 of their Dublin based aircraft.

As of mid April 2007 Qantas

Qantas

Qantas Airways Limited is the flag carrier of Australia. The name was originally "QANTAS", an initialism for "Queensland and Northern Territory Aerial Services". Nicknamed "The Flying Kangaroo", the airline is based in Sydney, with its main hub at Sydney Airport...

teamed up with Panasonic Avionics Corporation and AeroMobile to commence a three month trial that would "enable customers to send and receive e-mails, access the Internet and send and receive text messages from their own mobile phone"

On 18 October 2007 Ofcom

Ofcom

Ofcom is the government-approved regulatory authority for the broadcasting and telecommunications industries in the United Kingdom. Ofcom was initially established by the Office of Communications Act 2002. It received its full authority from the Communications Act 2003...

published proposals for the technical and authorisational approach that would be adopted to allow this for European GSM users on the 1800Mz band on UK registered aircraft. and on 26 March 2008 Ofcom approved the use of mobile phone-supporting picocells aboard aircraft in the United Kingdom. Airline companies will have to equip the aircraft with picocells and apply for licences.

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.