During editing the Shoreham to Brac movie I just happened to notice this section, during which the altitude went down very gradually but decisively.
I suspect it is too much to be explained by an OAT drop…
The autopilot does sometimes do funny things.
Peter wrote:
I suspect it is too much to be explained by an OAT drop…
Without pulling out my whiz wheel (if I can find it at all) I think these 40ft loss of (GPS) altitude can perfectly well be explained by a drop in temperature. Or pressure. Or both. All that is required is a little more than 1 degree C of 1HPa to produce such a change.
It might also be variation in the GPS altitude. Gliders logger records both pressure and GPS altitude, just looking at my last flight there is a 30m beween max and min differences. It can be fairly consistent for 10 min and then change by 10m in 30sec.
