how tech helped the hunt for flight MH370

Australian T3 - - PLANE TRUTH -

When Malaysia Air­lines Flight 370’s transpon­ders were dis­abled on the flight deck and the plane failed to be po­si­tioned by ei­ther civil­ian or mil­i­tary radar there was still one piece of tech track­ing the plane’s po­si­tion: ACARS.

The Air­craft Comms Ad­dress­ing and Reporting Sys­tem, fit­ted in 90 per cent of commercial jets, is sim­i­lar to SMS in that it’s used by pi­lots to send mes­sages and re­ceive weather re­ports. When a plane pow­ers up, ACARS es­tab­lishes a satel­lite link, but MH370’s was switched off. That’s not un­usual for flights to China, as it is Malaysia Air­lines pro­ce­dure to power down the sys­tem be­cause the ser­vice provider doesn’t cover China. How­ever, pi­lots can’t dis­able their ACARS en­tirely.

Ev­ery air­craft has a unique code with the satel­lite and as long as the plane is pow­ered up, that net­work con­nec­tion re­mains. Any air­craft fit­ted with the sys­tem and still in pow­ered flight will “ping” the satel­lite net­work of the op­er­a­tor ev­ery hour. It only stops this “elec­tronic hand­shake” if the plane loses power com­pletely.

In­marsat recorded eight of these pings from Flight MH370 via its 3F1 satel­lite, which was in geo­sta­tion­ary or­bit over Asia. It then used these pings to plot the plane’s likely course af­ter it had dis­ap­peared from ev­ery­one else’s grid.

Af­ter four days of data crunch­ing In­marsat es­tab­lished that the plane had trav­elled along one of two arcs, ei­ther head­ing north across south­ern and cen­tral Asia or south across the In­dian Ocean, about 1,500 miles south west of Aus­tralia.

Fur­ther anal­y­sis of the Dop­pler ef­fect of the pings, a phe­nom­e­non that al­ters the pitch ac­cord­ing to whether the tar­get is ap­proach­ing or leav­ing an area, led In­masat to de­duce that the plane had taken the south-bound arc, re­duc­ing the search area by 97 per cent.

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