Flight Data Recorders

I was reading this article about a Russian air crash - here is an excerpt...

Russian investigators have discovered that the cockpit-voice
recorder from the crashed Itek Air Boeing 737-200 contains no
trace of the ill-fated jet's final flight.

...

MAK adds that the quality of the flight-data recorder information
is "unsatisfactory" because of partial thermal damage to its
magnetic tape, caused by the intense fire which followed the crash.

Which made me think: magnetic tape?! Surely we've come far enough that
we can be using solid-state storage in flight data recorders?

Does anyone know why FDRs would still be using what, to me, is archaic
technology?

*Russian* ??

Michael Henry wrote:
I was reading this article about a Russian air crash - here is an
excerpt...


MAK adds that the quality of the flight-data recorder information
is "unsatisfactory" because of partial thermal damage to its
magnetic tape, caused by the intense fire which followed the crash.

Which made me think: magnetic tape?! Surely we've come far enough that
we can be using solid-state storage in flight data recorders?

Does anyone know why FDRs would still be using what, to me, is archaic
technology?

On Sun, 07 Sep 2008 20:36:59 +1000, Michael Henry
wrote:

I was reading this article about a Russian air crash - here is an excerpt...

Russian investigators have discovered that the cockpit-voice
recorder from the crashed Itek Air Boeing 737-200 contains no
trace of the ill-fated jet's final flight.

...

MAK adds that the quality of the flight-data recorder information
is "unsatisfactory" because of partial thermal damage to its
magnetic tape, caused by the intense fire which followed the crash.

Which made me think: magnetic tape?! Surely we've come far enough that
we can be using solid-state storage in flight data recorders?

Does anyone know why FDRs would still be using what, to me, is archaic
technology?

gee give them a chance! they've only just stopped using wire
recorders.

"Michael Henry" wrote in message
...
I was reading this article about a Russian air crash - here is an
excerpt...

Russian investigators have discovered that the cockpit-voice
recorder from the crashed Itek Air Boeing 737-200 contains no
trace of the ill-fated jet's final flight.

...

MAK adds that the quality of the flight-data recorder information
is "unsatisfactory" because of partial thermal damage to its
magnetic tape, caused by the intense fire which followed the crash.

Which made me think: magnetic tape?! Surely we've come far enough that we
can be using solid-state storage in flight data recorders?

Does anyone know why FDRs would still be using what, to me, is archaic
technology?

This occasionally happens, even though the FDR and CVR have considerable
thermal inertia and are located in a part of the plane that is least
frequently affected by both fire and mechanical damage. Also, the prose
above suggests that there was some data recovered from the cocpit voice
recorder and "some data" is probably more than they would have gotten from
solid state memory.

All the same, there has been a move from magnetic tape and metal foil to
solid state memory in the 20+ years that I have been out of that industry.
However, IMHO, that has been a case of obtaining more detailed data and
information (most of the time) and greatly reduced maintenance cost (the
frequent replacement of tapes and foils was shop maintenance) and accepting
far less robust media in order to accomplish those goals.

Personally, I can see more than one side of the arguments leading to these
changes and I have mixed feelings regarding the wisdom of same.

Peter

Peter Dohm said the following on 7/09/2008 11:55 PM:
This occasionally happens, even though the FDR and CVR have considerable
thermal inertia and are located in a part of the plane that is least
frequently affected by both fire and mechanical damage. Also, the prose
above suggests that there was some data recovered from the cocpit voice
recorder and "some data" is probably more than they would have gotten from
solid state memory.

All the same, there has been a move from magnetic tape and metal foil to
solid state memory in the 20+ years that I have been out of that industry.
However, IMHO, that has been a case of obtaining more detailed data and
information (most of the time) and greatly reduced maintenance cost (the
frequent replacement of tapes and foils was shop maintenance) and accepting
far less robust media in order to accomplish those goals.

Personally, I can see more than one side of the arguments leading to these
changes and I have mixed feelings regarding the wisdom of same.

There's no reason, except cost, why both can't be fitted. Solid state
can potentially record most of a flight and, if it survives provide a
considerable amount of data over an extended timeline. If the solid
state doesn't survive then there's still the legacy FDR and CDR.

A damaged hard disk might offer higher rates of recovery than a damaged
solid state drive. However, I'm not sure how well a hard disk would
tolerate mid air turbulence. Anyway, I think their ability to survive a
fire might be a lot less than that of the older devices.

Michael Henry writes:

MAK adds that the quality of the flight-data recorder information
is "unsatisfactory" because of partial thermal damage to its
magnetic tape, caused by the intense fire which followed the crash.

Which made me think: magnetic tape?! Surely we've come far enough that
we can be using solid-state storage in flight data recorders?

Does anyone know why FDRs would still be using what, to me, is archaic
technology?

Co$t is why. And while flash-based systems may offer more survivable
recording; consider the recent Qantas incident, where the
depressurization itself was overwritten by subsequent flight.

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

On Mon, 8 Sep 2008 13:08:56 +0000 (UTC), David Lesher
wrote:

Michael Henry writes:

MAK adds that the quality of the flight-data recorder information
is "unsatisfactory" because of partial thermal damage to its
magnetic tape, caused by the intense fire which followed the crash.

Which made me think: magnetic tape?! Surely we've come far enough that
we can be using solid-state storage in flight data recorders?

Does anyone know why FDRs would still be using what, to me, is archaic
technology?

Co$t is why. And while flash-based systems may offer more survivable
recording; consider the recent Qantas incident, where the
depressurization itself was overwritten by subsequent flight.

They could put in a bigger chip for longer recording. I thought most
DRs were only about 1/2 hr looping?

"Peter Clark" wrote in message
...
On Mon, 8 Sep 2008 13:08:56 +0000 (UTC), David Lesher
wrote:

Michael Henry writes:

MAK adds that the quality of the flight-data recorder information
is "unsatisfactory" because of partial thermal damage to its
magnetic tape, caused by the intense fire which followed the crash.

Which made me think: magnetic tape?! Surely we've come far enough that
we can be using solid-state storage in flight data recorders?

Does anyone know why FDRs would still be using what, to me, is archaic
technology?

Co$t is why. And while flash-based systems may offer more survivable
recording; consider the recent Qantas incident, where the
depressurization itself was overwritten by subsequent flight.

They could put in a bigger chip for longer recording. I thought most
DRs were only about 1/2 hr looping?

The original CVRs were 1/2 hour looping, carying three channels (or tracks)
of audio, and would erase the tape when the parking brake was applied at the
destination gate. Part of that was due to a combination of technical
necessity and convenience, and part was the dfproduct of negotiation between
the interested parties. The reusult was robust, in the sense that the
recovery of data did not depent upon any part of the equipment remaining
operable I am not familiar with the newer equipment; but would expect
that it would have been made functionally similar--with the possible
addition of more channels of audio.

The original FDRs contained a single use role of stainless steel foil, which
was marked by stylii. The result was *extremely* robust, but even the
second generation of such recorders had a very limited number of data
channels and required frequent depot level maintenance to replace the foil
rolls. Solid state memory simply does not have similar survivability and
there is virtually no change that it will within the next 25 years.
Therefore, solid state memory, in the event that it is actually in use, is
simply a way to obtain more channels of data at less monetary cost in those
cases where the data can still be recovered.

So long as the purpose of the data is to detect failures which can then be
resonably predicted, then it is probably a good trade.

David Lesher wrote:
... magnetic tape?! Surely we've come far enough that
we can be using solid-state storage in flight data recorders?

Does anyone know why FDRs would still be using what, to me, is archaic
technology?

Co$t is why. And while flash-based systems may offer more survivable
recording; consider the recent Qantas incident, where the
depressurization itself was overwritten by subsequent flight.

I can see how solid state storage is more expensive than tape, but I
would have thought that by the time you go through the whole
certification process the cost of the actual medium is just a small
fraction of the total cost... and if the solid state medium offers any
benefits over tape than that small extra cost would certainly be
justifiable.

The other issue you raise really surprises me: the small amount of
flight time for which recordings are kept. Some other posts have
mentioned half-an-hour loop! Does anyone know what volume of data this
entails?

Regards,

Michael


P.S. A quick mental calculation: I can go to Officeworks (in Australia)
and buy a 16 Gb memory stick for AU$100. OK, it's not going to meet the
same fault-tolerance and quality standards, but let's ignore that for
now For those of us in the iPod generation 16 Gb equates to around
300 hours of MP3 music. Obviously you would encode speech differently
and fit a lot more than that, but let's not worry about that. Of course
you also want to record other parameters (temperatures, pressures,
position of controls, etc). I'm just pulling numbers out of the air but
let's say you want to record 1,000 different parameters each sampled 10
times a second. Furthermore let's say the data for each parameter is
stored as a 32-bit value, which comes out to 40kb of data per second or
just under 150 Mb per hour. That's over 100 hours of parameters in our
16 Gb memory stick. Recording voice and data at the same time and I
figure you can fit about 80 flight hours in a $100 USB stick. Not bad
I'm obviously missing out on some important bits but it has made me
wonder: what would be the market for a really small, light, and cheap
uncertified flight data recorder...

In article ,
Michael Henry wrote:


The other issue you raise really surprises me: the small amount of
flight time for which recordings are kept. Some other posts have
mentioned half-an-hour loop! Does anyone know what volume of data this
entails?

I don't know the volume of data, but the CVR and FDR have different
amounts of data in terms of time. 1/2 CVRs are old. New ones can
record hours.

btw - for older aircraft, the biggest cost of putting newer FDRs with
(many) more channels is not the FDR itself, but all the sensors that
have to be installed.

--
Bob Noel
(goodness, please trim replies!!!)