The flights I'm talking about both show that they have pressure
altitude sensors. The two airports I checked in the area both showed
baro readings of around 29.82 at the time being examined in the flight,
which could account for 100' of error. But, the takeoff altitudes
match the takeoff airport elevation within 57' at most. The GPS
altitudes reported were as high as 19,000 ft, while the highest
pressure altitude reported was near 18,500. I'm removing one of those
particular flights from my consideration, as the overage was probably
only about 34 feet, and I could easily imagine that his altimeter was
off by that much. The other flight, though, would have almost
certainly indicated as high as 18,400. That's an obvious violation.
But what I'm really curious about is why SeeYou doesn't report this as
a violation when that function is activated.

Ed