On Thursday, July 16, 2020 at 2:19:19 AM UTC-4, wrote:
On Thursday, July 16, 2020 at 6:28:25 AM UTC+2, kinsell wrote:
On 7/15/20 7:34 PM, MNLou wrote:
Hi Nick -

When I want to analyze a flight from OLC, I download the IGC file and open it in See You.

I think the AGL numbers are See You are more accurate than from the OLC summary.

YMMV -

Lou


The barometric sensor in the logger is going to be assuming 29.92 inches
of mercury for atmospheric pressure, any deviation from that is going to
introduce an error on top of the instrument accuracy. So the AGL
calculations can be off quite a bit no matter what database is used for
ground elevation..

I would suspect OLC is using GPS altitude for AGL calculations, and probably using a fairly course terrain database which would explain the inaccuracies.

Moreover, I've seen many examples on OLC when it is mistaken on the takeoff time and place, but still assumes the altitude at the "takeoff" is that of the stated airport. This happens if, e.g., the logger does not have a GPS fix at the time of the real takeoff, or is reset later. So OLC "adjusts" the logged altitudes for its display. This results in grossly underestimated altitudes for the early part of the flight. (It apparently interpolates towards the landing altitude later in the flight.)