Mission time problem

Hello,
I have a problem with the estimated mission completion time.

When planning the mission in QGroundControl, each time the expected flight time is very high and overestimated by approximately 40 minutes. The actual mission time is shorter each time.

Have you ever had a similar problem?

Regards
Szymon

Have you checked if your speed and the distance for the mission in QGC match the time?

Yes, and it is not consistent with the calculations.

e.g. for a distance of 1200m and a speed of 3m/s where the time should be less than 7 min the time given is close to 50 min.

Can you provide the mission file?