Equipment and technology from all over the world, and on an unprecedented scale, are being brought to bear in the southern Indian Ocean in the effort to locate and retrieve the missing Malaysia Airlines Boeing 777-200.
In a briefing Tuesday, Malaysia’s defense and acting transport minister Hishammuddin Hussein said strong cooperation from the international community meant the challenge to find MH370, which disappeared March 8 and is now believed to be in a remote area of ocean off the western coast of Australia, was no longer diplomatic.
“It is now primarily technical and logistical. Because the scale of the investigation is now much more complex, the release of technical and logistical information will be handled differently,” he said. “As the search area has narrowed, new challenges have arisen, including managing resources in a remote search and rescue effort.”
New analysis of satellite data by Inmarsat and UK Air Accidents Investigation Branch (AAIB) concluded that flight MH370 ended in the southern Indian Ocean, Malaysia’s prime minister announced Monday, saying it was therefore “beyond reasonable doubt” that the aircraft was lost and none of the 239 people on board survived.
Providing more details on how and when that data analysis was performed, minister Hishammuddin said that in recent days Inmarsat developed a second innovative technique, which considers the velocity of the aircraft relative to the satellite. “Depending on this relative movement, the frequency received and transmitted will differ from its normal value, in much the same way that the sound of a passing car changes as it approaches and passes by. This is called the Doppler effect,” he said.
The Inmarsat technique analyzes the difference between the frequency that the ground station expects to receive and that actually measured. This difference is the result of the Doppler effect and is known as the Burst Frequency Offset.
The Burst Frequency Offset changes depending on the location of the aircraft on an arc of possible positions, its direction of travel and speed. To be confident in its theory, Inmarsat checked its predictions using information obtained from six other 777s flying on the same day in various directions.
“There was good agreement,” the minister said.
“While on the ground at Kuala Lumpur airport, and during the early stage of the flight, MH370 transmitted several messages. At this stage the location of the aircraft and the satellite were known, so it was possible to calculate system characteristics for the aircraft, satellite and ground station,” he explained.
During the flight, the ground station logged the transmitted and received pulse frequencies at each handshake. Knowing the system characteristics and position of the satellite, it was possible—considering aircraft performance—to determine where on each arc the calculated burst frequency offset fit best.
The analysis showed poor correlation with the northern corridor, but good correlation with the southern corridor—and depending on the ground speed of the aircraft—it was then possible to estimate positions at 0011 coordinated universal time (UTC), at which the last complete handshake took place.
“I must emphasize that this is not the final position of the aircraft,” the minister emphasized.
There is evidence of a partial handshake between the aircraft and ground station at 0019 UTC. At this time this transmission is not understood and is subject to further ongoing work. No response was received from the aircraft at 0115 UTC, when the ground earth station sent the next log on/log off message. This indicates that the aircraft was no longer logged on to the network.
“Therefore, sometime between 0011 UTC and 0115 UTC, the aircraft was no longer able to communicate with the ground station. This is consistent with the maximum endurance of the aircraft,” the minister said.
Malaysia’s investigation team has set up an international working group, comprising agencies with expertise in satellite communications and aircraft performance, to take this work forward.
Search operations in the northern corridor and in the northern part of the southern corridor, close to Indonesia, have been called off so that all efforts are focused in the southern part of the southern corridor, in an area covering some 469,407 square nautical miles.
Two Korean aircraft are en route to the area to join the multinational search operation, which includes aircraft and vessels from Australia, China, Japan, Malaysia, the UK and the US.
Although surveillance flights had to be canceled Tuesday because of bad weather, six Chinese ships are expected to arrive within the vicinity of MH370’s last known position by Wednesday morning. These ships include the ice breaker Xue Long. HMAS Success is also currently in the search area. Debris has been spotted in the seas by satellite and officers onboard Royal Australian Air Force surveillance aircraft, but nothing has been identified or retrieved.
A US Towed Pinger Locater—an instrument that can help find a flight data and voice recorder—is en route to Perth and will arrive Wednesday. The system will be fitted onto the Australian ship Ocean Shield, which is due to dock in Perth March 28. The Ocean Shield, fitted with the Towed Pinger Locater, is expected to arrive in the search area April 5.