I know this has been raised before but I have been unable to refind the answer. What altitude units are used in the Mission Planner and is it possible to change the units. I read that the default altitude is metres. Is that correct - can it be changed and if so how? 

The reason for the question is that my arducopter has just flown into the top of a tree despite the planned altitude being 40(metres - I thought). The tree is not huge and I expected it to clear it easily. The log shows that it held the set altitude of 40 so I don't think there was a problem with the Arducopter and I am sure the tree is not 120feet high.. 

I was lucky that the Arducopter fell through the tree and was virtually undamaged although the log shows the ground by the tree was at an altitude of -13 - the ground is definitely lower than at the takeoff point but 13m (40feet) sounds a bit much. 

Can anyone help me sort out what went wrong?


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  • Yes I have been frustrated by this as well!!  Like Mike said select the prefered units as he suggested but be aware I think this is only for the HUD its still in metric in advance param list!  If Im not mistaken there is even a setting in advance params in cm for altitude!!! Maby that's what gotcha??

    It would be a HUGE upgrade to mission planner to have all units in all aspects of setting up in params AND in the HUD display being either in metric or english. Having some that are and some that are not your preferred units of measure can lead to a mistake that leads to a crash. Sounds like yours is a perfect example of that. 

  • There is a Mission Planner settings page in which you select units of measurement, and from memory the default when first loaded was in feet.

    Simply go to Config/Tuning-Planner and select your preferred units.

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