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.
Was just looking at the Denver Airport, saw several airplanes at 0feet. Unless they dug a 5280feet hole, I am pretty sure the altitude displayed is at least some of the time based on QFE, not QNH/QFE....