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Aircraft Data In Crashes  
User currently offlineChrisNH From United States of America, joined Jun 1999, 4411 posts, RR: 2
Posted (16 years 3 months 4 days 9 hours ago) and read 2249 times:

Why wouldn't it be possible for airliners to send their performance data while in fligt via telemetry as opposed to storing it on (and thus relying upon) those FDRs? Seems to me that it could be done. Now, I realize that as a plane flies cross-country, different receivers would be needed, but with our ability to send and receive huge amounts of data, can't this be an option to always having to hope and pray that you (A) find the black boxes and (B) that they are in good shape? Also, if a plane crashes, it would be only the last hour or so of data that would be of any consequence.

7 replies: All unread, jump to last
User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 1, posted (16 years 3 months 4 days 8 hours ago) and read 2179 times:

Good idea in theory, as telemetry can be sent (missle launches and other test flights are good examples) but not practical. Where telemetry is used for military and tests, etc., it's on a very limited basis. If you were to deploy all that expensive technology (another issue in itself) to all airliners, can you *imagine* the bandwidth that would be required to simultaneously record multiple parameters from a few thousand aircraft? There'd undoubtedly be other issues as well, labor, "Big Brother" etc.) but I think cost/bandwidth would be the major two.

User currently offlineBoeingrulz From United States of America, joined Sep 1999, 555 posts, RR: 1
Reply 2, posted (16 years 3 months 4 days 8 hours ago) and read 2183 times:
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I do see how a limited use of telemetry could be useful for troubleshooting in-flight where the 32 or so parameters could linked to a maintainance or ops center for analysis.

I do understand that analysis does take quite a while when done traditionally but talemetry connected to a simulator could give a real-time situational information that could be helpful in diagnosing a problem.


User currently offlineJETPILOT From United States of America, joined May 1999, 3130 posts, RR: 27
Reply 3, posted (16 years 3 months 4 days 7 hours ago) and read 2175 times:

This is already done with ACARS. I forget what it stands for. I will have to look it up. But it is used to senfd information to the company in real time. I don't know how many parameters it sends. But I can't see why it couldn't be utilized in this application.

Not all jets are outfitted with this technology. But the majors are fast becomming 100 % equipted as the older AC are being replaced with newer ones.

MX can pull codes from the AC when there is a systems problem, and I believe they can communicate with the systems directly.

User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 4, posted (16 years 3 months 4 days 6 hours ago) and read 2177 times:

ACARS has its uses, and is great for OOOI times (out, off, on, in), enroute position reports, pireps, basic weather information, and some engine parameters. Most of those uses take only a small "burst" of bandwidth.

If you compare that with the bandwidth need to *continuously* transmit CVR and FDR information (4 CVR audio channels, and dozens of FDR parameters), I just don't think there are enough frequencies available to do this for all the aircraft that are airborne (on operating on the ground) to handle it... Like I said, cost and labor issues too, but bandwidth needs are huge....

User currently offlineKilljoy From Finland, joined Dec 1999, 646 posts, RR: 0
Reply 5, posted (16 years 3 months 4 days 5 hours ago) and read 2171 times:

Couldn't this be solved by transmitting data only in case of a problem? For example if an aircraft experienced a problem the pilot could immediately press some button that starts the streaming of data, both stored and new. Thus, only aircraft in trouble would gobble up bandwidth, and there is that much of it to go around.

Of course, this wouldn't help in situations where no-one had time to react, but these are fairly infrequent. And then we'd still have the boxes too.

User currently offlineJETPILOT From United States of America, joined May 1999, 3130 posts, RR: 27
Reply 6, posted (16 years 3 months 3 days 22 hours ago) and read 2163 times:

I know ACARS isn't the answer. I was just offering up a point that similar technology is there.

I don't understand the bandwidth idea. A satellite system has tremendous bandwidth. I'm sure something could be done with satellite communications.

User currently offlineBoeingrulz From United States of America, joined Sep 1999, 555 posts, RR: 1
Reply 7, posted (16 years 3 months 1 day 9 hours ago) and read 2156 times:
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According to my inside source (my cousin who works in flight test at Boeing). The bandwidth required for the initial testing at Boeing using telemetry, is about 15 megabytes per second. This is a huge amound of data representing hundreds of parameters. To transmit the data captured by most FDR's it would take about 1/10 of that, maybe 1.5 megabytes per second (still a very large amount of data).

Even though the bandwidth requirements are big, there is a move afoot to have the technology in place to transmit this data using satelittes in real time. The reasons are many but some overwhelming reasons there is so much interest in this technology is that it provides quick answers to questions and may save investigators the huge expense of physically recovering an aircraft for analysis.

I feel a bit uneasy about cutting out the physical examination of the plane as much information about the cause of the crash can't be containted the FDR or digital flight data transmissions. But in the case of an accident that happens in a remote area or in the deep ocean, this technology may be better than having nothing.


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