Mini 2 wont go below 20 feet when 200ft away

hendersg · Jun 6, 2022

Bit of an odd one today. Weather was clear and sunny with no wind or fog and I was flying off the side of a sloping grassy park. when the drone was around 210ft out I tried to descend and it wouldn't go below an indicated height of around 20ft (by then it was probably about 40ft above the grass as the ground had dropped away) I could make it climb but next time I descended it hit a hard stop at the same 20ft or so. No notifications in the display (or in logs on Airdata UAV) to suggest anything was wrong it just wouldn't descend. Bring the drone a little closer to maybe 180ft and I could descend as expected but going out again past 200ft it seemed to just not to want to go below a certain altitude.

I've never really noticed this behaviour before so I think it's new. Has anyone else experienced this?

FLDave · Jun 6, 2022

I assume the descent to 20 ft was ATL and you were 200 ft horizontally from take off point.. Next, at that point it was 40 ft AGL and the visible terrain was extremely variable. Was that area really suitable for landing or not? How would you describe the potential landing spots at 180 and 200 feet from your takeoff location. What is different about the 2 locations?

FLDave · Jun 6, 2022

According to AirData what was the barometric altitude (reference take off) and what was the vision system/sonar altitude above ground when it wouldn't descend below 20 ft ATL?

hendersg · Jun 7, 2022

FLDave said:
I assume the descent to 20 ft was ATL and you were 200 ft horizontally from take off point.. Next, at that point it was 40 ft AGL and the visible terrain was extremely variable. Was that area really suitable for landing or not? How would you describe the potential landing spots at 180 and 200 feet from your takeoff location. What is different about the 2 locations?

Yes that's correct the ground sloped away from my home point at at both 180 and 200ft the ground was uncut grass and the drone was likely around 40ft above it in both cases. It seemed to be all about the distance from home point and rather then anything else and it was almost a reluctance to go too low beyond a hard altitude a certain distance from home. It may well have always been like that and I only noticed as the ground fell away from me and I was hoping to follow the contours of the hill so needed to get down to just a few feet above the elevation I took off from (which would still leave me about 20ft AGL at both 180 and 200ft).

Meta4 · Jun 7, 2022

hendersg said:
Yes that's correct the ground sloped away from my home point at at both 180 and 200ft the ground was uncut grass and the drone was likely around 40ft above it in both cases. It seemed to be all about the distance from home point and rather then anything else and it was almost a reluctance to go too low beyond a hard altitude a certain distance from home. It may well have always been like that and I only noticed as the ground fell away from me and I was hoping to follow the contours of the hill so needed to get down to just a few feet above the elevation I took off from (which would still leave me about 20ft AGL at both 180 and 200ft).

None of that is normal.
Whether you fly higher or lower than the launch point makes no difference to the drone.
If the drone is 40 ft above the ground, nothing should stop it from going lower.

FLDave · Jun 7, 2022

Lacking details I'll assume the grass at the landing site was 12-24 inches tall. I'll assume that the AirData barometer height and the visual high were NOT the same. I'll also assume that the landing area was NOT level, making it an unsuitable landing area.

Meta4 · Jun 7, 2022

FLDave said:
Lacking details I'll assume the grass at the landing site was 12-24 inches tall. I'll assume that the AirData barometer height and the visual high were NOT the same. I'll also assume that the landing area was NOT level, making it an unsuitable landing area.

Landing protection doesn't stop the drone when it's 40 feet above ground.

Chaosrider · Jun 7, 2022

Meta4 said:
None of that is normal.
Whether you fly higher or lower than the launch point makes no difference to the drone.
If the drone is 40 ft above the ground, nothing should stop it from going lower.

That raises an interesting question.

DJI drones have a hard-stop max ATL altitude of 500 m, about 1640 ft.

Is there a similar limitation for BTL altitudes? Are you limited to not more than 500 m BTL? Perhaps flying from a cliff, or the top of a mountain?

Enquiring minds...

;-)