KUALA LUMPUR - It is unlikely that any overwritten portions of the recordings from the cockpit voice recorder in MH370's black box can be recovered if the device is found.
Andrew Herdman, director-general of the Association of Asia Pacific Airlines, said the voice recorder only had two hours of recording time before it looped over the previous recording.
"I don't think it will be possible to recover anything (from it) other than the last two hours (of MH370's eight-hour flight)," he said on the sidelines of the International Air Transport Association Ops Conference.
He said that while it was possible to recover deleted files from a computer hard disk, this could not be done with sound recordings.
The crux of the MH370 mystery is why the airliner deviated from its original course to Beijing from Kuala Lumpur early in its flight and made turns that led to it heading in the opposite direction.
Herdman believed that the flight data recorder, also inside the black box, would be the more useful device to help investigators answer that question.
"It is usually this piece of equipment with its comprehensive data parameters that has enabled investigators to work out exactly what happened in the other aviation incidents.
"That is why so much effort is being expended to recover the (MH370) black box," he said.
According to Herdman, aviation experts had considered replacing the black box with a system that constantly transmitted the recordings and data to a ground facility after the Air France Flight 447 crash in 2009.
But satellites, which would be needed to direct the data stream from aircraft to ground station, did not have enough data transmission capacity, "especially since the satellites would need to handle tens of thousands of flights a day," he said.
Another study looked at transmitting bursts of the data to a ground facility if something abnormal occurred on the aircraft.
"But this is not feasible on a system-wide basis," Herdman said.