On 25 February 2008, at about 2128 Eastern Daylight-saving Time, the flight crew of a Boeing Company 747-338 (747) aircraft, registered VH-EBY, detected a smell that slowly increased in intensity. At that time, the aircraft was cruising at 37,000 ft and was about 275 km west south-west of Sydney, NSW.
The flight crew donned their emergency oxygen equipment and transmitted a PAN call to air traffic control. The aircraft was cleared direct to Sydney for landing and was escorted to the terminal by the airport fire services for disembarkation.
An inspection by the operator determined that loose terminal connections to the left windshield heat element resulted in electrical arcing and fumes on the flight deck.
The aircraft manufacturer has a programme to replace the windshields in the 747 with an enhanced windshield heater wiring connection that should address the risk of electrical arcing in that component.
