"Smitty Two" wrote in message
news
In article ,
"Arfa Daily" wrote:

Still, apparently, they have now located some wreckage 400 miles out into
the Atlantic, so I guess that they have around 28 days left to locate and
recover the CVR and FDR boxes, which apparently are likely to be lying in
around 13000 feet of water. Seems like the batteries for the pingers are
good for about 30 days, and the transmitter is just about man enough to
get
a signal through 15000 feet of salt water. I guess that if they can
recover
them and they continued to function for any time after the initial
'event',
then we could know quite quickly what the primary cause of it going down
was.

This whole "black box recovery" stuff seems silly to me. Given the
number of accidents in which the recorders are never found, or when
found are FUBAR, and given today's communications technology, I don't
know why data isn't being constantly streamed to ground recording
centers.

Ah. A point that I made to my pilot friend yesterday, and apparently, some
of the flight data is streamed to the ACARS system continuously, via
satellite. He says that height, speed, heading, inertial nav position
estimate, and true GPS position, amongst other things, are transmitted.
Which then begs the question of why it is so difficult to locate the
position of a downed aircraft. I guess that if it is coming down from 7
miles up, with significant forward speed, and not necessarily in one piece,
that might make it more difficult. Still, I would have thought that it would
have given them a bit more of a 'ball park' area to be looking in, than
seems to be the case. In fact, I remember seeing an episode of ACI, where
they took the place of last transmission of an aircraft, and then plotted by
computer, how the pieces would fall, and came up with a location for a door
I think it was, which struck me as pretty clever.

But yes. Given the level of compression that can be applied to data streams
these days, it does seem archaic to record all this data on board the item
that you are trying to protect. I suppose privacy issues might come into
transmitting flight deck chat, but I'm sure that with the encryption systems
available, and operating the same rolling window system, that could be
overcome.

I also questioned the state these boxes are in when found, but he said not
to be misled by their appearance. Apparently, if they were working in the
first place - and that's not always a given, which is a bit worrying - the
chances are that they will still be working when recovered. Seems that the
actual recorder is inside a sphere, and the battered bit that you always
see, is just an outer case, which might contain some ancilliary electronics,
and is shaped to fit a rack in an equipment bay. Also, these days, they
employ solid state memory, rather than any kind of electro-mechanical
recording mech.

Arfa

Arfa