Hisham: Satellite data conclusive


Analysis done by Inmarsat and AAIB was convincing to conclude on MH370’s last position, says Hishammuddin Hussein

Alyaa Azhar, FMT

Acting Transport Minister Hishammuddin Hussein provided more information today on the new analysis based on satellite data that concluded that Malaysia Airlines Flight MH370 did indeed end in the southern Indian Ocean.

Last night, Prime Minister Najib Tun Razak said the new analysis of satellite data from Inmarsat and UK Air Accidents Investigation Branch (AAIB) concluded that MH370 ended in the southern Indian Ocean.

The new analysis 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.

The Inmarsat technique analyses the difference between the frequency that the ground station expects to receive and one that is 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 its speed.

In order to establish confidence in its theory, Inmarsat checked its predictions using information obtained from six other B777 aircraft flying on the same day in various directions. There was good agreement.

Flight MH370 transmitted several messages during the early stage to the Kuala Lumpur Internationl Airport.

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.

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 which the last complete handshake took place.