Does APM Prioritise Waypoint Attainment over Altitude?

In order for me to understand a recent incident I need to ask the developers this: does the APM mission code (3.1.5) prioritise waypoint attainment over altitude maintenance?

If this is the case it would make sense, because assuming the aircraft was attempting to RTL in a strong headwind, it would be better for the aircraft to get as close to possible to home, even if it flies into the ground rather than maintaining an altitude failing to penetrate into wind, eventually crashing more heavily when power runs out.

Would appreciate developer feedback.


no, altitude has priority.
the opposite was a safety risk until recently, people crashed by asking higher AS that the UAV could handle. (or setting GS , not taking wind into calculation)

Nor would i like to see a UAV chop somebody in the face due to unplanned descend while going for a WP/HOME.

To put it simply;do not fly in conditions it con’t handle, and take manual control when outside AP’s authority /(you have more autority in manual, than AP modes are allowed - which is another safety feature.)

Hi Andre

That is strange then, because my quad kept flying as it lost power, perfectly on course to its next waypoint. I found it where it ‘landed’ upside down, right on the waypoint track. It was flying at 10m.s mission speed into a probably upper wind of 6m.s on smaller props than I designed the quad for. The log auto analysis did fail it on thrust with this configuration. It used what thrust it had to maintain its course, while it steadily descended from its mission altitude. The battery still had well enough power.


PixHawk quad, 3.1.5, 3508 380kV motors, 30A ESCs on 5s lipo, AUW about 2.1kg

oops - my bad.
the mentioned fix was added first in ArduCopter 3.2-rc1 (9-May-2014)
sorry - you are right 3.1.5 does prioritize groundspeed over altitude - it’s just so long ago I forgot.

Nope, broken in 3.1.x, IIRC. Coming back in 3.2.

(yep - that’s why I corrected myself) :slight_smile:

So if I arm then hit ‘auto’ it will go straight up until wpt 1 alt is reached THEN proceed to wpt 1?

govsux: we were discussing speed vs ability to maintain altitude.
you seem to be asking if position is set/maintained during climb , and yes it is.