Missing MH370: How to disable communications

Missing MH370: How to disable communications

KUALA LUMPUR - Just how easy is it to disable communications systems in an aircraft?

There are three in an aircraft -- Very High Frequency (VHF), High Frequency (HF) and a Satellite Communication Group (SATCOM), which includes the transponder and Aircraft Communications Addressing and Reporting System (ACARS).

FAS Udara Flying Club president Captain H.S. Dharan, who has been flying for more than 10 years and has spent 24 years in the aviation industry, said the transponder provided and indicated the position and altitude of the aircraft.

He said ACARS was a digital datalink system for transmission of short, simple messages between aircraft and ground stations via radio or satellite.

Dharan said all of this was performed automatically by the ACARS management unit and other associated avionics systems, without flight crew intervention.

As part of the growth of ACARS functionality, the ACARS management units also interfaces directly with a control display unit located in the cockpit.

"All the above must be switched on and off manually by the technical crew, who, in MH370's case, is the pilot," Dharan told the New Sunday Times yesterday.

He said the power supply for all these components could also be disabled permanently by disconnecting the circuit breakers in the cockpit or in the avionics bay below the cockpit.

"The avionics bay is a space inside the structure of the airplane where electronic devices, such as receivers of communications radios, navigation systems, radar equipment, transponders and other electronics, are installed.

"It is in a secured location within the aircraft with restricted access. On most aircraft, it is below the cockpit."

On how long it would take for these electric components to go offline should it be turned off manually, he said the effect was immediate.

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