Why did I crash my Mini

[jschain]

I live in a rugged, heavily wooded part of the Ozarks so open spaces to fly are few. So this morning I decided to fly my new Mini from the drive along the road to an open area of a few acres. I did loose track of the time and the battery alarm went off. I immediately tried to bring my drone down as I was in a good place to land. The Mini descended but stopped about 15-20 feet above the ground and refused to descend any more. As a new pilot and in a bit of a panic I let off on the left stick and the drone shot up to about 100 ft. (RTH altitude). I managed to bring it down again but again it refused to descend the final 15-20 feet. 3x and the battery died and then it did descend the final distance. So, why wouldn't it come down those last 15-20 feet? My theory is that the meadow is about 15-20 lower in elevation than my home which was home for the drone. Does this make sense or am I missing something? (It did crash on thick grass so no damage.)

 

[Thomas B]

Likely it was because RTH was already initiated by your drone. Many controls are disabled in drone initiated RTH.

 

[Meta4]

So, why wouldn't it come down those last 15-20 feet?
My theory is that the meadow is about 15-20 lower in elevation than my home which was home for the drone.
Does this make sense or am I missing something?

The elevation of your home point makes no difference to anything.
You can lean anywhere, higher or lower than the launch spot.
As usual, what actually happened will probably be shown in the recorded flight data.

Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
Or .. just post the txt file.

 

[jschain]

That doesn't fit with the manual. When the alarm went off I immediately tried to land. The drone came down to 15-20 ft. and refused to descend any more. I also, cancelled the RTH as the manual said by pressing the RTH button. The drone could be flown away from "Home" and was as there was a hill in that direction that gave me some extra elevation. So it could me maneuvered. It just refused to descend the las t 15-20 ft.

 

[Meta4]

That doesn't fit with the manual. When the alarm went off I immediately tried to land. The drone came down to 15-20 ft. and refused to descend any more. I also, cancelled the RTH as the manual said by pressing the RTH button. The drone could be flown away from "Home" and was as there was a hill in that direction that gave me some extra elevation. So it could me maneuvered. It just refused to descend the las t 15-20 ft.

Your flight data will solve the mystery.

 

[hiflyer201]

Meta will solve this for you ..I'm repeating this for him because he's a man of few words

 

[Rodders]

What i have found that the Sensors seem to sense if the ground is safe to land or not, so i move to a different piece of ground and then land.

 

[gemniii]

What i have found that the Sensors seem to sense if the ground is safe to land or not, so i move to a different piece of ground and then land.

Could you explain what you mean by "seem to sense"

 

[Rodders]

They sense the ground and if the Drone things it is not safe to land it will hover over that bit of ground, and it will stay there until it runs out of battery or you move the Drone to a safer bit of ground and it will land. That is what i have found myself it will do.

 

[gemniii]

They sense the ground and if the Drone things it is not safe to land it will hover over that bit of ground, and it will stay there until it runs out of battery or you move the Drone to a safer bit of ground and it will land. That is what i have found myself it will do.

Is that documented someplace?

 

[Meta4]

Meta will solve this for you ..I'm repeating this for him because he's a man of few words

But the OP is a man of little data.

 

[Rodders]

Ok , Meta4 tell all. ???

 

[Meta4]

Ok , Meta4 tell all. ???

When/if the OP gets around to providing his flight data, I'll probably be able to.
But without that data, there's not much to go on.

 

[DOC LEMIEUX]

I had the same thing happen. Flight data showed Ruth command. Upon checking I read with the latest up date threw download might have been an issue. I refreshed the download to my planes and controllers. Then completed I’m calibration and compass. No problems before upgrade and none now after refresh. Hope this helps

 

[jschain]

I live in a rugged, heavily wooded part of the Ozarks so open spaces to fly are few. So this morning I decided to fly my new Mini from the drive along the road to an open area of a few acres. I did loose track of the time and the battery alarm went off. I immediately tried to bring my drone down as I was in a good place to land. The Mini descended but stopped about 15-20 feet above the ground and refused to descend any more. As a new pilot and in a bit of a panic I let off on the left stick and the drone shot up to about 100 ft. (RTH altitude). I managed to bring it down again but again it refused to descend the final 15-20 feet. 3x and the battery died and then it did descend the final distance. So, why wouldn't it come down those last 15-20 feet? My theory is that the meadow is about 15-20 lower in elevation than my home which was home for the drone. Does this make sense or am I missing something? (It did crash on thick grass so no damage.)

So, I have reviewed the flight data and it shows two things. First, I tried to fly too long on a 2/3 charged battery. My stupid mistake, but as a beginning flyer I learned from it without any damage to the drone. That's good. Second, and this was my question above, why wouldn't my drone come all the way down and land. The data shows that the drone stopped the descent at -32.8 ft. At this point it absolutely would not come descend any more. Convert 32.8 ft. to metric and you get 10 meters, off by .0084. That is too close to be accidental. Somewhere in the programing there is code that will not allow the drone to descend to more than - 10 m. It may be only on RTH or it may be at any time. I haven't tested the latter.

Thank you all for your comments and help. If I test for, or you test for flight below - 10 m. post the results here please.

Steven

 

[Meta4]

Somewhere in the programing there is code that will not allow the drone to descend to more than - 10 m. It may be only on RTH or it may be at any time. I haven't tested the latter.

You've made a guess without any data to support it.
All of DJI's drones can descend a long way past -10 metres.
If they stopped at -10 metres, many flyers would have found out by now.
Post your flight data and someone might be able to find what actually happened.

 

[gemniii]

I believe that the height is based on where it was launched.

 

[DanMan32]

Indeed the bottom sensors can prevent landing if the sensors believe the landing area is unsuitable, but that happens at around 2 ft above ground, not 28ft.
Besides, you'd see a warning with an option to override.

My bet is RTH was engaged. To engage/disengage, you have to press and hold for a second or two. When RT'H is engaged, app goes "do do do, beep-beep, beep-beep, beep-beep..."

Posting the log as instructed in the link will provide the answer.

 

[Mladen Matković]

That doesn't fit with the manual. When the alarm went off I immediately tried to land. The drone came down to 15-20 ft. and refused to descend any more. I also, cancelled the RTH as the manual said by pressing the RTH button. The drone could be flown away from "Home" and was as there was a hill in that direction that gave me some extra elevation. So it could me maneuvered. It just refused to descend the las t 15-20 ft.

Probably RTH cancellation was not sucesfull.

 

[Meta4]

It looks like the OP isn't really interested to find out what caused this.
He's had nearly a week but hasn't posted the data that's necessary to find out what really happened.
ANd it definitely had nothing to do with the height of the drone as he incorrectly guessed.