In article , Eric Greenwell
writes
Ian Strachan wrote:

snip

In at least one case, after manufacturer tests indicated a line of
investigation, further flight tests were carried out by GFAC with
that recorder and resulted in several World Records being validated.
Without this process it would not have been.

I thought a primary reason for having a manufacturer around was for
examining the flight recorder when cheating was suspected. They should
be the best authority on whether the instrument or it's code has been
modified.

Eric, the case referred to was not a security problem but a mis-set
Engine Noise Level (ENL) system in the recorder concerned. This
rendered the proof of engine-running (or rather of not-running!) in this
motor glider problematical. As several world records hung on this
recorder (it is always better to carry more than one for such important
flights!), FAI consulted GFAC on the matter, which is normal procedure
and applies to NACs as well (such as the SSA's badgelady who has also
been known to contact us for opinions on anomalies found in recorder
evidence).

First we asked that the manufacturer to look at the recorder concerned
and to maintain its original state (that is, not to open it up and
re-set it). The mis-setting was confirmed and apologies were made. All
ENLs were very low and it was difficult to see where the engine had been
run and where it had not. Of course the pilot should have picked this
up before going for the records, but we know that pilots are more
interested in flying than instrumentation! Because the manufacturer
did not have access to the type of motor glider that had been used for
the world record claims I asked for it to be sent to me for flight
tests.

As you know, I fly from Lasham in the UK where we have some 200 gliders
on site. I was able to find an example of the same motor glider that
was used with this recorder in several world record flights. The
suspect recorder was flown in the MG concerned together with a "control"
recorder. This confirmed the ENL levels found in the world record
flights. Comparing them with the "control" data enabled us to confirm
which of the (low) ENL levels were engine running and which were
background cockpit noise and other short-term "clunks and clicks" that
sometimes occur.

In addition, the record flights were still in the memory and the
recorder's VALI program check worked, thus proving that it had not been
re-set or altered since the world record flights. A combination of this
evidence enabled a statement to be made to FAI that the engine had not
been run between the start and finish of the glide performances
concerned.

Sorry that this explanation is not short, but it does illustrate a
number of things that are worth noting.

I am very pleased when records and other flight performances can be
"saved" when otherwise they might have been lost due to anomalies in the
evidence. We should be rigorous on standards of evidence, but sometimes
independent after-flight checks and tests can maintain standards despite
certain anomalies.

The above is not a unique case, there have been many others that are
referred to GFAC for an opinion. We are always willing to look at IGC
flight data files from anyone where it is thought that a strange reading
or other anomaly exists.

So it's not only security issues, which is where we came in at the
beginning!

--
Ian Strachan
Chairman, IGC GNSS Flight Recorder Approval Committee

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Bentworth
Alton, Hampshire GU34 5LA
ENGLAND


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