Mavic Pro took-off without given command and crashed :(

[u238]

Hello guys!

Thanks for all the input... so I tried to recreate the accident (without props)...
The AC was in the same environment, same sea state, same all... just no props!

Nothing odd happen, it was still idling on the floor, motors didn't increase RPM.
Sorry for the late reply, but internet connection on-board a ship isn't the most reliable one
I have attached the flight records if someone is willing to take a look.

Thanks all!

 

[sar104]

Hello guys!

Thanks for all the input... so I tried to recreate the accident (without props)...
The AC was in the same environment, same sea state, same all... just no props!

Nothing odd happen, it was still idling on the floor, motors didn't increase RPM.
Sorry for the late reply, but internet connection on-board a ship isn't the most reliable one
I have attached the flight records if someone is willing to take a look.

Thanks all!

Recreating the event will depend on the ship's motion being appropriate. I recreated it by manually causing the aircraft motion. In any case, I have no doubt at all that the cause was as described in posts #72 and #74.

 

[BudWalker]

Recreating the event will depend on the ship's motion being appropriate. I recreated it by manually causing the aircraft motion. In any case, I have no doubt at all that the cause was as described in posts #72 and #74.

I agree.

 

[u238]

@sar104 , amazing...
Now at least I know what happen...
Unfortunatelly, even the drone is under warranty, since I don't have any flight logs to prove what happen - I'm still gonna have to repair it myself

 

[sar104]

@sar104 , amazing...
Now at least I know what happen...
Unfortunatelly, even the drone is under warranty, since I don't have any flight logs to prove what happen - I'm still gonna have to repair it myself

I'm not sure that the logs would help. DJI might well argue that leaving the aircraft running on a moving platform, leading to this effect, was pilot error. The fact that many of us did not realize that this would happen in that situation likely wouldn't make it a warranty issue.

 

[u238]

Agree... thanks anyway

 

[Spy808]

A guy posted this on youtube... Learned it by watching and not doing awhile back...

 

[Simmo]

A guy posted this on youtube... Learned it by watching and not doing awhile back...

Perfect explanation!

 

[Lake_Flyer]

When I idle my Inspire1 on the bow deck of my boat it constantly adjusts its revs with the rocking of the boat, up to a point that it almost takes off by itself. So I'm always alert on this and never let it idle too long before taking off from a rocking boat. Also, when landing on water with floats, you can see it's still trying to hover in the water while idling. When I shut down the motors it sinks 2 inches deeper.

Idling is still considered flying by a drone.

 

[sar104]

When I idle my Inspire1 on the bow deck of my boat it constantly adjusts its revs with the rocking of the boat, up to a point that it almost takes off by itself. So I'm always alert on this and never let it idle too long before taking off from a rocking boat. Also, when landing on water with floats, you can see it's still trying to hover in the water while idling. When I shut down the motors it sinks 2 inches deeper.

Idling is still considered flying by a drone.

That's not actually correct according to the FC data - it sets a couple of state parameters according to whether it is flying or not, and at idle, before takeoff, those parameters indicate that it is not flying. However - as this shows - it can be triggered to switch to flight mode. I have a vague recollection that when it was first released, one of the stated properties was that it could be thrown into the air and would fly. The ability for the FC to do that would require the FC to be able to make such a switch.

 

[Lake_Flyer]

I have a vague recollection that when it was first released, one of the stated properties was that it could be thrown into the air and would fly. The ability for the FC to do that would require the FC to be able to make such a switch.

I was talking about my experience with my Inspire1 which is probably not designed to throw up in the air.

As soon as an IMU gets a different reading from the barometer and it senses motion with its anemometer, while it's idling, it can't really think anything else than that it's flying, and responds with commands to the ESC's. So basically you can throw any drone, with complete IMU config like our drones have, into the air while idling and it will start to hover.

 

[sar104]

I was talking about my experience with my Inspire1 which is probably not designed to throw up in the air.

As soon as an IMU gets a different reading from the barometer and it senses motion with its anemometer, while it's idling, it can't really think anything else than that it's flying, and responds with commands to the ESC's. So basically you can throw any drone, with complete IMU config like our drones have, into the air while idling and it will start to hover.

I was simply noting that until it senses that kind of motion the FC status is explicitly on the ground, rather than flying. You may be right that all the DJI FCs can react like that.

 

[MavicCF]

I was simply noting that until it senses that kind of motion the FC status is explicitly on the ground, rather than flying. You may be right that all the DJI FCs can react like that.

I may be late noticing, but I just realized that was you.

 

[BudWalker]

I may be late noticing, but I just realized that was you.

Yes, quite the facelift I'd say.

 

[sar104]

Yes, quite the facelift I'd say.

Oh - now I understand the comment. Yes - needed something more colorful.

 

[u238]

So, let's say, after I disembark from the ship, go home, fix the MP and take it on my speed boat (6.5 meters)... can I take-off and land safely from the boat?

 

[RayOZ]

Turn it on, let it idle on the deck, put the remote down and see what happen.
As long at the speed boat isn’t moving, I think take off is fine. I personally would hand catch that try to land on a boat.

 

[sar104]

Turn it on, let it idle on the deck, put the remote down and see what happen.
As long at the speed boat isn’t moving, I think take off is fine. I personally would hand catch that try to land on a boat.

I would think, based on this event, that the best approach is not to start the motors until ready to lift off immediately.

 

[RayOZ]

There’s another possible scenario that might caused this. The drone was inside a ship, in a closed environment. When someone opens and closes an exit door, the air inside gets displaced and cause the barometric pressure to change momentarily. So, if someone went outside, and the door shuts (inwards), pressure inside would increase, and the drone thinks it was falling, and so rev’d the motors.

 

[u238]

There’s another possible scenario that might caused this. The drone was inside a ship, in a closed environment. When someone opens and closes an exit door, the air inside gets displaced and cause the barometric pressure to change momentarily. So, if someone went outside, and the door shuts (inwards), pressure inside would increase, and the drone thinks it was falling, and so rev’d the motors.

This was my initial theory.... but...
In post #81 I have posted flight records of the tests performed within the same environment - You are welcome to inspect them if you like.
The barometric pressure was surely changing, as the altitude on the RC was changing - although the MP was idle on the floor the whole time.
I was opening and shutting the door of the compartment on purpose to affect the air pressure change and consequently a take-off - but it didn't happen... as many times I tried.

As @sar104 already explained and tested it was more likely caused by ship's movement.