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egarding missing Flight MH370, planes can crash-land on water and then sink leaving no wreckage, due to strong currents that make debris travel far or because all parts have sunk to the seafloor.

The 4.5-kilometer deep search area is 20 square-kilometers wide around an area where sonar picked up a signal on April 8 consistent with a plane'€™s black boxes.

There is a lot of silt down on the bottom that could even cover a plane, so searchers are bringing in better sonar equipment to look through the silt.

Some airlines have installed technologies to allow phones to be connected within the airplane as it flies. Such systems were tested on scheduled flights in 2006, and in 2008 several airlines started to allow in-flight use of mobile phones. Some airlines installing the equipment are also considering the issue of '€œphone-free zones'€ and '€œquiet time'€ on long flights.

Maybe the pilot decided it was a '€œphone-free zone'€ and '€œquiet time'€ and then flicked the switch so nobody could connect to the phone network. Similarly, the pilot may have flicked other switches that turned other things off like the transponder.

The Aircraft Communications Addressing and Reporting System (ACARS) on the plane sends manual or automated text messages from the plane back to base and vice versa.

It is able to send messages using a system of satellites that are run by the British company Inmarsat, which is perfect for a plane at sea as it removes the limitation of needing to be close to ground-based transmitters to send radio messages.

ACARS messages can be manually initiated by the pilot or ground base, but the system will also send out timed '€œhandshakes'€ automatically to the satellites.

Inmarsat by using its satellites and the MH370 ACARS automatic '€œhandshakes'€ tracked MH370 to where the plane ended up and where they are searching.

Pity that Malaysia did not purchase from Inmarsat an ACARS US$10 upgrade that would have automatically given '€œhandshakes'€ more frequently with better positioning, plus information about the plane'€™s altitude.

Once it was found out that MH370 flew into the South Indian Ocean, one of the most remote areas of the world, it took Australia time to get a proper ping receiver/locator from the US.

When it arrived in Australia it then had to be fitted on a ship and taken out to the search area.

So much time was wasted looking for the plane near Vietnam and toward China, and the black box batteries were running low as it sent off pings all that time. Maybe Malaysia should have listened to
Inmarsat earlier.

Soon, as the Australian ship arrived in the search area near Australia, it started to receive pings from MH370'€™s black box, the longest being 2 hours 20 minutes of receiving repeated pings.

Later they had received lots of repeated pings from other locations and from them they could triangulate a search area much smaller than they had before.

Eddy Saf
Jakarta