[Yosemitest]

Here's some information about equipment.
Todays technology in air traffic control automates hand-offs between different radar facilities.
The facility initiating the handoff keys certain functions on the computer that causes the aircraft's data block to start blinking.
The receiving facility "joy-sticks" and keys another function key to finish the hand-off, only after he has established radio communication and verification of target data from the pilot.
I can't remember how long the data-block will continue to blink if the receiving controller does not finish the acknowledgement of the handoff, but it is a long time.
IF the hand-off is not completed, THEN it starts a communication between handing off facility and the receiving facility until the aircraft's position is determined.

This is where the pilot or copilot of Malaysia Airlines Flight 370 turned off the transponder, and stopped all verbal communication with air traffic control.
He probably thought it would allow him a little extra time before the search for his "lost" aircraft would begin, and it did allow a little extra time and question-ability about any primary radar target returns, being on the edge of both radar facilities' distance limits to receive a return.
But because of the Letters of Agreement between facilities about how to handle handoffs, it probably caused the "dropped secondary radar target" to generate a search start much quicker than if the aircraft had turned the transponder off after establishing radio communication with the receiving facility (Vietnam).
Depending on the volume of traffic that controller was working, if the transponder was turned off a few minutes after saying "hello" to the receiving facility, it would probably have gone longer before it was noticed that the secondary radar (computer generated) target had been dropped.

[zipper]

Here's some information about equipment. Todays technology in air traffic control automates hand-offs between different radar facilities. The facility initiating the handoff keys certain functions on the computer that causes the aircraft's data block to start blinking. The receiving facility "joy-sticks" and keys another function key to finish the hand-off, only after he has established radio communication and verification of target data from the pilot. I can't remember how long the data-block will continue to blink if the receiving controller does not finish the acknowledgement of the handoff, but it is a long time. IF the hand-off is not completed, THEN it starts a communication between handing off facility and the receiving facility until the aircraft's position is determined. This is where the pilot or copilot of Malaysia Airlines Flight 370 turned off the transponder, and stopped all verbal communication with air traffic control. He probably thought it would allow him a little extra time before the search for his "lost" aircraft would begin, and it did allow a little extra time and question-ability about any primary radar target returns, being on the edge of both radar facilities' distance limits to receive a return. But because of the Letters of Agreement between facilities about how to handle handoffs, it probably caused the "dropped secondary radar target" to generate a search start much quicker than if the aircraft had turned the transponder off after establishing radio communication with the receiving facility (Vietnam). Depending on the volume of traffic that controller was working, if the transponder was turned off a few minutes after saying "hello" to the receiving facility, it would probably have gone longer before it was noticed that the secondary radar (computer generated) target had been dropped.

Are you familiar with ADS-B and CPDLC?