NZ air crash cited in cellphone interference study

Wreckage at the site of the 2003 crash. Photo / Christchurch Star

A fatal plane crash in New Zealand has been cited in a report stating that the use of cellphones and other devices in midair may create a "perfect storm" of conditions that can have disastrous consequences.

This is because most personal electronic devices emit electromagnetic waves which can interfere with a plane's electronics, an investigation by the New York Times has found.

Although it has remained difficult to prove, experts suspect electronic interference has played a role in some airline accidents and have warned passengers not to be complacent.

The 2003 crash in Christchurch was used as an example where a mobile phone is believed to have interfered with the plane's navigational equipment.

Eight people were killed when the plane flew into the ground short of the runway.

The pilot had called home some time before the crash, remaining connected for the last few minutes of the flight.

A final report into the incident by the New Zealand Transport Accident Investigation Commission found that "the pilot's own mobile phone may have caused erroneous indications" on the navigational aid.

"Electronic devices do not cause problems in every case," said David Carson, an engineer with Boeing. "However it's bad in that people assume it never will."

Older planes may be particularly vulnerable to interference. Another contributory factor is the plane's altitude.

"A plane is designed to the right specifications, but nobody goes back and checks if it is still robust," said Bill Strauss, an engineer and former doctoral student at Carnegie Mellon University.

"Then there are the outliers - a mobile phone that's been dropped and abused, or a battery that puts out more [power] than it's supposed to, and avionics that are more susceptible to interference because gaskets have failed.

"And boom, that's where you get interference.

"It would be a perfect storm that would combine to create an aviation accident."

In 2007, another pilot recounted an instance when the navigational equipment on his Boeing 737 failed after takeoff. The problem resolved itself after a passenger was told to turn off a hand-held GPS device.

However new technology is combating the potential danger electronic devices can pose to aircraft. In July last year the Australian Communications and Media Authority ruled that mobiles do not disrupt aircraft navigational equipment if airlines install special technology, paving the way for travellers to be able to make calls and send text messages in flight.