Re: 757 Flight Recorder Located

From:         msb@SEI.CMU.EDU (Mark Bell)
Organization: Software Engineering Institute
Date:         14 Mar 96 17:49:28 
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29-Feb-96 01:24	bay@daacdev1.stx.com (John Bay)	 writes :

>To carry the thought a step further (and perhaps to extremes), does current
>technology make it feasible for airliners to transmit their operating
>parameters to the ground in real time?

To borrow a phrase from Willie Nelson : "If you've got the money honey,
I've got the time" !

>From a purely technological viewpoint, I believe it is feasable.
Doing some coarse back of the envelope engineering, you could have
asynchronous downlinks to ground recording stations, or asynchronous
uplinks to a satellite transponder for subsequent downlink to
a ground recording station (the latter view solves mid-Atlantic type
situations).  Alternately, you could have a synchronous replay to
ATC radar or IFF interrogations (sorry, it's been a while since my
EW days, and I can't remember if the U.S. Mode 3/C reply is triggered by
radar or a seperate IFF signal). You could also contrive a set of
conditions such that when any are exceeded would trigger an asynchronous
transmission of aircraft data -- the idea here is to capture the
data only if one or more data items were outside of acceptable range,
and perhaps be able to capture the disaster as it's happening, thereby
decreasing the system data storage requirements.  I can think of other
ways also, but you get my point...

I believe the real issue is economic feasibility.  Are the recurring
and non-recurring costs of such a system worth the benefits ?
We, the taxpayers, would be footing the bill.

On the one hand I'd say no, as airliner crashes aren't very
common, and the CVR and DFDR are usually recovered. On the other hand,
we might know what really happend to US Air Flight 427 that went
down here in Pittsburgh about a year ago.  This is a subjective
decision

Now, you could also have technicians monitoring all those downlink
signals to monitor the aircraft systems in real-time in the hopes
of detecting a failure condition before it happens... etc...

Regards.


Mark S. Bell                           412-268-7925 (Voice)
Software Engineering Institute         412-268-5758 (Fax)
Carnegie Mellon University             ** These are my opinions,
4500 Fifth Ave, Pittsburgh PA.,15213      not those of the SEI or CMU **