IGC APproval for GPS with WAAS

"Adrian Jansen" wrote in message
...
You might want to consider the implications of WAAS. I have no direct
experience, but the principle is that you take an external signal and use
it
to 'correct' the GPS location to another place - hopefully more accurate.
But what is to stop you sending bogus 'corrections' and making the GPS
think
its somewhere else entirely ? The WAAS signals are much easier to
generate
than the original GPS satellite signals. Sounds an easy way to cheat to
me.

--
Regards,

I do not believe it is at all easy to fake GPS WAAS and GPS is already
acceptable for position. But it is very easy to fake a barograph.

Ivan

In article , Ivan Kahn
writes

snip

I do not believe it is at all easy to fake GPS WAAS and GPS is already
acceptable for position.

But it is very easy to fake a barograph.

A drum-type baro, yes, it has unfortunately been done and some cases
have been publicised in the public domain. Not easy if it is an
electronic pressure sensor embedded in a secure GNSS flight recorder.
You have to fake both the pressure and GNSS-altitude traces and make
them similar. Now that is less that straightforward, I think.

Yes, you could probably fake one, or the other. But both together is
not easy. How many people have access to a GPS simulator and a pressure
chamber? And the ability to co-ordinate the two into a plausible IGC
flight data file that still passes the security checks?

Also, the faked fixes would have to agree with the weather of the day,
thermal/wave conditions, winds with height, etc. All of which can be
checked against other flights done on that date and in the same area.

Finally, on flights to be validated an OO has to observe the recorder in
the glider and the time and place of takeoff and landing. How do you
fake this beforehand?

Yes, I suppose that anything is possible but I suggest that the "height
of the fence" that IGC has put up against cheating or malpractice with
GNSS flight recorders, is suitably high. Make it too high and we would
not fly because there would be too many checks to do first!

--
Ian Strachan