Why does OLC display wrong altitudes?

On Tuesday, February 12, 2019 at 12:52:05 PM UTC-5, Ramy wrote:
I’ve seen this occasionally in my flights if the takeoff altitude was not determined correctly, or if I forgot to start the logger before the tow started. I dont recall if it is OLC or the logger which adjusting your takeoff altitude to airport altitude, but if there is mismatch there, the rest of the altitude trace will be wrong.
The solution is to edit the flight in OLC and manually adjust the start to your release time, which seem to fix this issue.

Ramy

Ramy: I think you're on to something there, as all the examples we've found seem to be of log files that are missing the takeoff. Although the effect of the "start" altitude on the displayed altitudes seems to dissipate later in the flight. But when you manually choose the start point, do you have to tell OLC the altitude of the start, or does the act of choosing that point tell it to believe the altitudes in the log?

I think they should always assume the altitudes in the log file are correct (for use in the web-page display). Even if the location of the start of the log is not at the declared airport. Certainly they shouldn't assume that the altitude of the start of the log is that of the airport, when the location is clearly not at the airport.

Moshe, I am not sure if correcting the start always fixes the issue, although it did for me in few cases, not sure exactly how.
Regardless, one would always check that OLC identified the release correctly and adjust if needed, otherwise this may significantly impact your score.

Ramy