PoirotryInMotion
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Found the link I was looking for, so am bringing up the post from earlier page in this thread. The ACARS system can be shut down (partly) from the cockpit, but the rest of the shutdown (affecting those "handshake" satellite pings) would've required someone going down the hatch to the lower deck and disabling electronics down there. That second step was not done, evidently.
Here's the relevant part:
Originally Posted by miley
Disabling the satellite communication (ping) is a two person operation - one person to fly the plane and one person to enter the cabin and crawl down the hatch to the lower deck where the electronics bay is located.
Hypothetically, maybe there wasn't a second person to do it.
That second step (BBM) was not done. Read that fact yesterday and screenshot the article; I'll find the link.
(That's why we have the "handshake" pings we do.)
Here's the relevant part:
ACARS
Another clue is that part of the Boeing 777's Aircraft Communications Addressing and Reporting System (ACARS) was shut off.
The system, which has two parts, is used to send short messages via a satellite or VHF radio to the airline's home base. The information part of the system was shut down, but not the transmission part. In most planes, the information part of the system can be shut down by hitting cockpit switches in sequence in order to get to a computer screen where an option must be selected using a keypad, said Mr Goglia, an expert on aircraft maintenance. That's also something a pilot would know how to do, but that could also be discovered through research, he said.
But to turn off the other part of the ACARS, it would be necessary to go to an electronics bay beneath the cockpit. That's something a pilot wouldn't normally know how to do, Mr Goglia said, and it wasn't done in the case of the Malaysia plane. Thus, the ACARS transmitter continued to send out blips that were recorded by the Inmarsat satellite once an hour for four to five hours after the transponder was turned off. The blips don't contain any messages or data, but the satellite can tell in a very broad way what region the blips are coming from and adjusts the angle of its antenna to be ready to receive messages in case the ACARS sends them. Investigators are now trying to use data from the satellite to identify the region where the plane was when its last blip was sent.
http://www.smh.com.au/world/missing...to-takeover-20140317-hvjge.html#ixzz2wKbzQSQg