My apologies for the (slight) thread drift, Glen.
On the subject of the allegations by Mr Carmody against the pilot of an aircraft whose “instruments”, according to Mr Carmody, “say he was at one hundred and twenty five feet”, I’m following with interest a thread on another aviation forum about a pilot who says Flightaware always shows his altitude as 300’ below that indicated on the aircraft’s altimeter, not explicable by differences in QNH. Some very interesting information linked in that thread.
The difference between Height-Above-Ellipsoid versus Height-Above-Geiod in the Geometric Altitude parameter in ADS-B is fascinating. And wouldn’t it be funny (not for the pilot concerned) if the 125 number cited by Mr Carmody is actually a parameter expressed in metres rather than feet...