Re: 757 flight recorder located

From:         Andy Zeitlin <>
Organization: The MITRE Corporation
Date:         07 Mar 96 02:04:40 
References:   1 2 3
Followups:    1
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Currently, FAA and industry are developing a new capability called
Automatic Dependent Surveillance - Broadcast (ADS-B) which would
broadcast certain parameters in real time, both to nearby aircraft
(for collision avoidance, traffic display, or future operational
traffic procedures), and potentially to the ground.

In the near term, the system probably will use the Mode S data link,
which is very limited in its capacity. The messages will carry
aircraft position, velocity, direction, identity, but little else.
Contrast this to a flight data recorder which tells about engine
speeds, flaps, vertical rates, bank, pitch, etc etc.

In the longer term, another data link could greatly expand the message
contents. However, it doesn't make sense to continuously broadcast
info. that rarely will be needed if bandwidth is at all scarce. ATC
might make regular use of some data; crashes are rare, even more so
where the FDR can't be easily located.

Also, the problem of receiving data on the ground implies receivers
will be put in place. The problem this thread is discussing mainly
applies to a crash far from "civilization"; hence, the low likelihood
of finding a receiver there. A better approach might be a
satellite-linked path such as ADS-oceanic uses. However, this
bandwidth is somewhat limited and expensive. In fact, another
satellite, SARSAT, is used internationally for search and rescue; but
it couldn't support retrieval of flight data recorder parameters.