Originally Posted by
Capt Fathom
FR24 displays Altitude based on Standard Pressure. If there is a large difference between that and the local QNH, you will need to apply the difference to see the real altitude.
I recall the local QNH at the time was 1027mb. That’s a 420 feet adjustment.
Yes, that's probably correct - while there are, I believe, a very small number of FR24 feeders running software that allows them to input the QNH adjustment at source, we can almost certainly discount that here.
So that would make the altitudes at the initiation of the GA (approximately):
Mode C/Mode S: 650'
AMSL: 1050'
AAL: 625'
Rad Alt/AGL: obviously dependent on terrain (if anyone with local knowledge can help, it was 1.6 nm from the THR, roughly overhead the Keilor Stadium)