According to the ABC (Australia) the sequence of events around the time time MH370 blinked off radar screens has been clarified by the investigation team. This new series of events would rule out theory two in my post from yesterday.
Apparently it goes like this:
- ACARS is disabled
- 12 minutes transpire
- Air traffic control (ATC) initiate hand over to the next controller
- MH370 replies with just a “All right, good night”
- MH370 does not make contact with the next assigned controller
- 2 minutes transpire
- Transponders are disabled
- A short time later, the aircraft makes a turn toward land, flies for several more hours and is not seen or heard from again
The Handover process
To help control ATC workload (and factors affecting radio wave propagation) , the world’s airspace is segmented into various ‘sectors’ with an ATC responsible for one or more sectors at a time. As an aircraft approaches the boundary of a sector, the ATC instructs the aircraft to contact the next center by stating the new controller’s callsign (how they are to be addressed) and the radio frequency. The aircraft is required to respond by reading back the frequency. The process is designed so that if the aircraft reads back an incorrect frequency, the error may be detected by the ATC and the aircraft is less likely to have communication trouble finding the next controller. The handover conversation typically goes as follows:
ATC: Generic 456, contact Melbourne Centre, 132.0
Aircraft: 132.0, Generic 456
It is also common for both ATC and flight crews to add greetings and goodbyes as to these handovers but from a technical stand point that is not required and the most important information is the new frequency. In my experience the absence of a read-back is not always a priority from ATC as generally, the crew know the next frequency and are expecting the handover and ATC also know that if they call the wrong frequency they’ll usually come back to the first one and sort any problems out. The trouble with MH370 is that they subsequently disappeared.
What does it mean?
From this latest version of events, if I were the investigation team assigned to investigating the mindset of the crew, I would be focusing on the First Officer at this stage. I say this because systems were being turned off and his voice was heard on the radio (with presumably no struggle in the background) prior to it going missing.
Has anyone done this before?
Yes. There have been many cases (a list can be found here) where aircraft have been used as vessels for suicide. From my recent research, lead causes seem to be trouble with spouses, finance and insurance fraud.