Why the emphasis on keeping everything private all of the time? That just
makes people think that things are being covered up. If there are issues,
there's no reason for them not be discussed civilly in public. That way
everything is on the up and up, and everyone else can learn something in the
process.

Mike Schumann

"Doug Haluza" wrote in message
oups.com...
I think you owe him an apology. Using SeeYou and setting QNH (5888ft)
at the start, gives a max altitude of 18,261 MSL. But this gives a
final altitude of 4819 MSL at an airport elevation of 4697'. This means
the altimeter setting changed during the flight, and the change made
the altitude appear to be high by more than 100' at the end. So this is
a mitigating facor.

Even neglecting this, an 18,261' altitude from this logger is within a
reasonable error budget.

First we have to allow that the pilot is not using the logger as his
primary flight reference altimeter. The altimeter is subject to certain
errors, and the errors increase with altitude. Adding these errors
could explain most, if not all of the 261' deviation in the worst case,
even if the altimeter was calibrated for IFR flight.

Ramy reports that the logger has a calibration error of +169 feet at
18000 feet. We would also need to know the error at around 5000 feet to
account for using field elevation for the initial setting. But unless
the error at 5000' was more than +169 feet (which is unlikely), this
would further mitigate the discrepancy.

The other thing that adds to the error is that the Volkslogger is using
cockpit static venting. This will cause a variable error depending on
canopy sealing, vent position, etc. Also the logger is calibrated at
room temperature, and it was probably quite a bit colder at 18,000'.

The bottom line of this is that we can't say that he did not go above
18,000', but we can't say that he did either. We could reduce the
uncertainty somewhat if we had an ATC altimeter setting, but it's not
likely to change the analysys much. So in this case, we have to take
the pilot at his word when he says he did not bust Class-A. We really
should not get into this kind of hair splitting anyway, because it is
not productive.

This also shows why these kind of disputes are better handled in
private, as I have been repeatedly requesting here. Please contact the
pilot if you can and politely point out your concern. If you do not get
a satisfactory explanation, do not start a confrontation. Contact the
SSA-OLC Committee by email at olcatssadotorg (use the symbols to
get a valid address). We will handle the issue confidentially to
protect all parties from embarrassment. If we find that the flight log
shows a problem, we will ask the pilot to remove the flight claim. If
not, we will put a note on the claim to explain the discrepancy.

Now let me add one note of caution. You will need to allow a safe
margin below 18,000' MSL when flying to account for altimeter (and
pilot) error. A 500' buffer would be prudent, unless you kept your
altimeter calibrated for IFR flight (or had a calibrated transponder
encoder with readout corrected for altimeter setting).

Either this pilot was using a buffer with an altimeter that read low,
or he was not using a buffer with an altimeter that did not read low.
We don't know for sure. But if your altimeter reads low, or the
altimeter setting changes and you don't reset it often, you could have
a bust that cannot be explained away. In this case, all the factors
fell in the pilot's favor, but you may not be so lucky.

Doug Haluza
SSA-OLC Admin

wrote:
OK in order to sort a dispute that is running between Ramy and myself.

I have Strepla which shows minor airspace and altitude violations which
Seeyou does not.

FYI. Ramy's Logger Calibration report shows a +169ft error at 18000ft.

The flight in question is this one here .
http://tinyurl.com/fe2k8

I ask users of both software to look at this flight and report their
findings.

If this exercise highlights a bug in Strepla I owe Ramy an apology.

Thanks

Al