The Indian Ocean is a very big place to look for an object half a meter long, 12 cm wide and 15 cm high. That is the size of the Honeywell solid state flight data recorder (SSFDR) Model ED-55 carried in Malaysian Airlines 777-200ER Flt 370. Without it, the world can never know what happened to the aircraft that disappeared on March 8, let alone why.
After a massive search by air and sea in the wrong place, the focus is now on an area of the ocean almost 1850 kms due west of Perth. That is at approximately 32 deg south. Till now the search has been concentrated in the Roaring Forties, as far south as 44 deg, based principally on photographs of supposed wreckage from a variety of satellites – American, Chinese, French, Thai, and analysis of brief hourly ACARS signals.
As suggested in two previous reports on this website, it was highly unlikely MH370 could have reached so far south, given the fuel load it was carrying. At takeoff from Kuala Lumpur for its flight to Beijing, the aircraft was known to have fuel for at most seven hours in the air.
Forty minutes later it changed course radically, and disappeared from air traffic control surveillance. It was then at 35,000 feet and travelling at 867km/hour. The last established position for the airliner was at the north of the Strait of Malacca, one hour and 34 minutes after takeoff.
On any rough calculation, the remaining five and a half hours of remaining fuel would take it less than five thousand kilometers. That is about the location of the new search area, 1100 kilometers north of the zone that has been the focus.
The analysis of the ‘pings’ from the ACARS system trying to make contact finally confirmed that the plane’s route had been south, not north from the Malacca Strait. But it seems that the search zone was based on an estimation of flying time measured by six instead of five ‘pings’. (The plane emitted seven pings, the first while still on the ground in Kuala Lumpur, and the second an hour later).
The SSFDR should have survived the crash into the Indian Ocean. It is designed to withstand an impact shock equivalent to 3400 times the force of gravity and has been tested in a demonstration to still yield its information after a simulated crash at 4800G. It should be able to withstand deep-sea water pressure up to 20,000 feet for thirty days. It retains as much as 25 continuous hours of aircraft performance – engine and flight control settings, all time-coded, supplied by the flight data acquisition unit.
The cockpit voice recorder, a similar device, is not likely to be so helpful. It records only two hours of conversation and other noises from the flight deck, but then re-records continuously in a loop.
Finding the SSFDR will depend on finding the wreckage site, but even then the box could be within a radius of several kilometres. Much has been made of the urgency in locating it before its batteries die after 30-35 days. It is unlikely it will be found within that period, since its signals can be heard only within a distance of one mile, even if it is intact. In the Air France crash of Flt 447 in the Atlantic, it was more than two years before the box was recovered. And when it was found, investigators determined it had been damaged in the crash and never transmitted a signal.
At this point, nobody knows what happened in or to the Malaysian airliner, or why it took its strange, deadly deviation from a normal overnight passage to China.
With all hope gone, the search for the wreckage field and its clues to the location of the flight data recorder, is now at the beginning of a long and arduous process which could last for years.
Geoffrey Luck, a pilot, was an ABC journalist from 1950 until 1976. In January, 2014, he recalled how a combination of inexperience and power lines very nearly cost him his life