SYDNEY, Australia (AP) _ Authorities are investigating whether the autopilot on a Qantas flight to London jammed because passengers used electronic games, computers or mobile phones on board.

The 400 passengers on the Sept. 4 flight thought they were going to crash as the plane lurched heavily on its side and dropped sharply through the air.

According to an incident report obtained by The Australian newspaper, the captain had to correct the plane's altitude after a silent malfunction in the autopilot.

The malfunction had pitched the aircraft 700 feet off course when it was meant to be in a holding pattern above London Heathrow airport.

Since January 1994, the Bureau of Air Safety Investigation has logged about 50 incident reports from airlines in Australia involving personal electronic devices.

A spokesman for the bureau, which is investigating the Heathrow incident, told the newspaper there was no conclusive link yet between the use of devices that emit electromagnetic energy and the dozens of reported malfunctions.