Dangers From Onboard Use Of PEDs/Mobile Telephones

There is ample recorded evidence that Personal Electronic Devices (PEDs) including Mobile Telephones are: -

  1. Used during flight whether permitted or not and
  2. Have the potential to interfere with aircraft communications, navigation and, perhaps more rarely, control (engine, FMS) systems.

Yet the Aviation Industry is coming under intense pressure to permit unrestricted use of PEDs, including Mobile telephones, in flight.

The problems of using PEDs in flight are extremely difficult to quantify due to the almost entirely random nature of the Electronic Emissions generated, which depends not only on the power of the emitting device but also on its orientation, the position within the aircraft and whether frequency modulation occurs and magnifies by combining signals from other PEDs, to name but a few of the many variables involved.

In the mid 1990's the CAA issued a Notice to AOC Holders banning the use of Mobile Telephones throughout the flight following an increasing number of MOR's highlighting the interference experienced to the aircraft systems. It would appear, however, that the general public remain unaware of the potential dangers involved and, as revealed by recent tests on a number of internal flights within the USA, continue regularly to use their mobile telephones in flight when specifically banned from so doing.

Airbus is introducing a system (ONAIR) to allow mobiles to be used by ensuring, in effect, that by providing an onboard 'aerial' (a picocell), each mobile will automatically detect this aerial and remain on its low power setting. However, if that is not a fail safe system and the 'aerial' becomes inoperative, then presumably all those mobiles will automatically switch to high power whilst searching for the nearest aerial on land some 30,000 feet below, with possible catastrophic effects upon the aircraft equipment and systems.

There seems to be conflicting opinion concerning whether or not, even with an onboard aerial, a mobile telephone automatically goes to high power when initially switched on until an aerial is detected. It is understood that initial restrictions on use may be imposed such that no more than a dozen or so mobile telephones may be used at any one time and only when the aircraft is above 10,000 feet altitude in order not to interfere with ground based aerials. How this could ever be monitored and enforced remains problematical. Additionally, some mobile telephones, due to poor quality control during their manufacture, have been known to emit up to ten times their normal power.

Certification of new aircraft generally involves testing by 'bombarding' the aircraft electronically from the outside - in, to ensure the correct shielding and protection from interference, but in terms of the carry-on PEDs it would now seem appropriate also to mandate certification standards that require 'bombarding' from the inside - out. This should serve to ensure the integrity of the aircraft systems but is no guarantee.

Legally banning the use of mobiles and other PEDs known to affect systems, as suggested by a court Judge several years ago, would probably not resolve the problem as evidenced by the number of people currently flouting the law by using their mobiles whilst driving.

There would appear, therefore, to be a very limited number of realistic options open to the industry:-

  1. Certificate all new build aircraft to ensure that any PED/Mobile used onboard now, or anticipated in future, cannot possibly interfere with any of the aircraft systems. It is most unlikely, however, that the aviation industry would be willing to undertake such action to ensure the integrity of their current fleets of aircraft.
  2. Provide through a Fail-Safe system the facility for unrestricted use of PEDs/Mobiles in flight (assuming the popular demand exists) or
  3. Continue to ban the use of Mobiles throughout the flight and other PEDs during critical stages of flight and ensure compliance by providing detection and warning (and possibly jamming) equipment to the Flight and Cabin Crews in order to pinpoint immediately the source of any emissions likely to provide interference. If/when detected take action against the person responsible for endangering the safety of the aircraft, as now occurs in China (resulting in a US $250 fine).

Meanwhile, it is recommended that greater publicity and information be provided to the public of the potential hazards and that further in flight research is now undertaken by the CAA/EASA in order to establish the scale of the problem. Unrestricted use of Mobiles in flight must be delayed until the safety of their use has been proven and guaranteed not to be a problem. The question remains, what, if anything has changed in the last ten years to make unrestricted use of mobile telephones onboard aircraft safe? Finally, the Air Safety Group recommends that the JAA Temporary Guidance Leaflet (JAR-OPS) No. 29 published in October 2001 be implemented to require onboard detection equipment enabling the Crew to detect any unauthorised use of mobile telephones, particularly during critical phases of flight.

Following a recent incident in February 2008 where a B747 exceeded its selected airspeed and deviated from its required track because of a business class passenger refusing to switch off his mobile telephone, the Group wrote to Flight International raising the possibility of one or more mobile telephones possibly contributing to the B777 accident at Heathrow by countering the demand for increased fuel flow and power at a critical stage during final approach. This letter was published in the 4th March issue of Flight.

In response to questions in the House of Commons, the Aviation Minister gave an assurance that G registered aircraft would not be permitted to use mobile telephones in flight until both the CAA and EASA could ensure their safety.