Badges ? ... We don't need no stinkin' badges

Andrew Warbrick wrote:
At 08:36 20 September 2005, Jancsika wrote:

Andrew Warbrick

Here we go again. Vali-ewa.exe only checks the hash
of the file against the G line, if there are no datum
records in the file your OO or the NAC's badge secretary
should reject the claim.


Hmm, and why does it print this info same cases?

'The following fixes are not recorded as being relative
to the WGS84
geodetic datum. Care should be taken that these fixes
are not used
to validate the flight.

22 fixes from 05-04-04 11:22:59 UTC to 05-04-04
11:24:02 UTC inclusive.

EW Flight Recorder security checks indicate file '544E7AM3.igc'
is VALID.'


That's interesting, it would appear I was wrong. Are
you saying that file was generated with a 'mouse GPS'
and contains more than 22 fixes?

I was under the impression the datum record would only
be generated by Garmin's proprietary PGRMM sentence.
My 'mouse GPS', based on the SiRF chipset definitely
can't output this sentence.

I'm afraid I can't do any testing, as I haven't owned
an EW for nearly four years now. If you've got sample
files, feel free to send me a copy (I do have some
old files generated with an IGC upgraded EW model B
and a GPS from the approved list).

I checked the official specification and you are partly right. GPS
shall send the datum change but if there was no change (or GPS boot up)
while the EW is connected you won't have datum info. In this case the OO
is responsible to ensure that the GPS sends (is set to do) WGS84 based data.
The specification says also something about the previous vali
revision. So probably you referred to a previous version.
It's not important, it's just something to show that we are almost at
the COTS security level


/jancsika

Jancsika wrote:
I checked the official specification and you are partly right. GPS
shall send the datum change but if there was no change (or GPS boot up)
while the EW is connected you won't have datum info. In this case the OO
is responsible to ensure that the GPS sends (is set to do) WGS84 based
data.
The specification says also something about the previous vali revision.
So probably you referred to a previous version.
It's not important, it's just something to show that we are almost at
the COTS security level

The approval document makes it quite clear in Annex B1.1 that "only
listed GPS units which conform to the criteria given under 'hardware' at
the beginning of this document are permitted for IGC flight evidence"
and that it is the official observer's responsibility to "make a record
of the type and serial number of the GPS unit." So, independent of
whether it is detectable using the IGC file alone, an official observer
would have to falsely state the type of GPS unit used on the badge
application form for a claim using a GPS unit other than those listed.
If one can't trust OOs to follow the stated requirements, or make
truthful statements about EW equipment, there will be far more room for
OO mischief with COTS-based evidence.

No one questions that the EW units provide a lesser level of security
than other approved flight recorders. That is why they are only
approved for badges up to Diamonds. They nonetheless provide some
features that COTS units will not. In particular, they record pressure
altitude, and generate a digital signature that provides some nominal
assurance that the IGC file has not been tampered with after download.

Once again, I'll state that I support use of COTS evidence for badges.
But, any successful proposal is going to have to find a way to address
the concerns of the IGC delegates concerning the pressure altitude and
the validity of the evidence. If one argues that it is silly to be
concerned about these things for badges, then I (and others) will ask:
why don't we simply accept the pilot's signed statement that a badge
flight was completed as stated, and require no further evidence?

Marc