clearedtocross,
ANY form of data
transmission adds a whole string of imponderables, the data link being lost at the critical moment being only one of them.
Having the FDR and CVR "listen" to the aircraft until the last possible second, then try to protect and retrieve those data, has been the method of choice so far.
"Delta modulation" only needs the 'base value' to be corrupted briefly for the data to become unusable, until the new base has been transmitted (video is a good example... we're seeing it here locally right now, with the introduction of digital TV and dodgy reception....)
To me, if something is going to be done, it should be an upgrade of the ULB, with louder pings, and maybe a transponder function after a certain time. Not sure if it can be done within the same "form, fit and function" envelope?
It may be a "sellable" idea for the FAA, ARINC, etc. because it would improve matters in all cases where a recovery from underwater is required.
As to the data transmission idea, one could say we already have a primitive kind of that in the form of ACARS.... without the ACARS messages from AF447 we wouldn't even be able to make any wild guesses.
Originally Posted by HamishMcBush
Re: auto-jettison of black box: How does the aircraft predict when it's going to crash and let the black box go? Interesting idea.
Much what I was saying, really. You want those boxes on board to the last second.
CJ