Originally Posted by
mini
From Checkers "A GMT/UTC is recorded from either the Capt's Clock, ACARS, or an internal clock on the Data Acquisition Unit. However, synchronization will probably be done based on ATC tapes and radio-keying parameters from each aircraft."
Wouldn't it make sense to have data recorders take their time stamp from the GPS equipment?
PS, I haven't sussed how to do the quote thing...
It depends what recorders you have got hold of and which type they are. In general, there may be a timestamp at the start and then the recorders all seem to run at slightly different rates if they are the older generation, say 1 in 60 difference, so you get 59 to 61 second minutes. You can work out relative speeds and then timestamp with the same ATC transmission. They you have to coordinate all the different ATC clocks etc.
Having got the reference time frames, then you need to work out when each data block was obtained, as the time that it writes to the memory or tape can be different. There could be a significant difference between each vital parameter here.
It can be quite a job just doing this part, without any analysis whatsoever.