An incident with an overheating mobile phone on board an aircraft highlights the importance of taking precautions with lithium battery-powered devices, especially when travelling, according to the ATSB.

On 25 November 2011, shortly after a Rex Airlines Saab aircraft arrived at Sydney airport, a passenger's Apple iPhone began to overheat and give off smoke in the passenger cabin. A cabin crew member used a fire extinguisher on the phone, and after several minutes, the smoke cleared.

The ATSB investigation found that a small metal screw had been misplaced in the phone's battery bay-probably during earlier repairs. The stray screw punctured the battery casing, causing an internal short circuit that led to heating-heating that increased as the battery reacted and began to break down.

Significantly, the phone repairs had not been conducted by an authorised service provider.

ATSB Chief Commissioner, Mr Martin Dolan, said passengers should be aware of the safety measures needed for flying with lithium battery-powered devices.

"When travelling with mobile phones, laptops and other portable electronic devices-or just their batteries-passengers should, wherever possible, carry them in the cabin, and not in checked-in baggage," Mr Dolan says. "This reinforces the Civil Aviation Safety Authority's recommendations for flying with lithium battery-powered devices."

"The incident also highlights the importance of good maintenance and repair processes for these devices, and the risk of using non-authorised repair agents."

The complete final report is available on the ATSB website.

The Civil Aviation Safety Authority's advice on carrying lithium batteries on aircraft is available on the CASA website, at www.casa.gov.au/dg/