ACARS
I have worked on installing the latest ACARS system in my airline and the amount of information that one can get from ACARS is mind boggling. In fact I would dare to say that is as good as FDR , but obviously lacks the CVR capability of recording voice.
ACARS works with VHF or SATCOM , there is also a HF data solution but it is not common and only few airlines use it.
As far as the AF A330 is concerned , I have no doubt that they had SATCOM as the postion of the A/C over the ocean was away from any ground base recivers . hence MCC or Operation Control could get all the messages from the stricken aircraft.
One thing that remains to be seen is how Air France has selected to operate the ACARS on this route. Transmissions using SATCOM are expensive, many airlines are selctive in the amount and the frequency of information that is transmitted by ACARS using SATCOM. Some configure the system to collect all the data and when they reach a VHF station , it dumps all that data to base using the much cheaper rate.
A very good question was raised about the G force . YES , ACARS can send this information as well and it will be quite helpfull in the crash analysis. Whether the G force was recieved by Air France or not is not clear.
ACRAS is the primary tool for Aircraft Tracking with many airlines operations control centers. However , again it depends on how the airline has configured the system. Obviousley it is a waste of money to send postion fix every five minutes (specially under SATCOM) , neverthanless ACARS is second best flight tracking system after Radars with an added advantage that a Radar has certain range while ACARS is not necessarily bound by range limitation.
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