Why did my Mini 4 Pro crash?

aeciolemos · Dec 15, 2023

Luckyguy9 said:
What was the damage to the drone?

Front left arm broke off its hinge and the gimbal support on that side was dislodged. The gimbal snapped back in place, but the arm is broken and needs to be replaced. I don't know if that happened in the collision or when it hit the grass.

MS Coast · Dec 15, 2023

aeciolemos said:
I am not sure how it crashed. I think it hit something but I can't understand why. I don't think it hit the light pole, it was between me and where the drone should have been. The issue is, I had my back. I did not see where it went and I did not record it. I wish I had.

I have been flying for 5 years. I never used anything with active tracking or obstacle avoidance, always flying on manual mode and I have never crashed. I know to avoid power lines and twigs. I trusted the obstacle avoidance and active track. I was playing around with it.

From your description it does seem it crashed into a light post, but wouldn't that be something it should know to avoid? Having said that, the greatest mystery for me is why it circled back behind me if I clearly set it to follow me from the southwest, as I put in the pictures. It should have stayed well clear of both the lamp posts and the trees.

In conclusion, my greatest question is why it crashed. Why did it go where it was not told to or not supposed to. And why did the obstacle avoidance not avoid the crash?

The drone follows you in a position relative to your motion, not a compass direction or a position relative to your body. You may have walked a bit to the left along the path relative to your overall direction so that the drone moved to the right and encountered a tree branch.

DJI really does its customers a disservice with their promotional materials by suggesting that the tracking modes and obstacle avoidance can follow a person in very complex environments. There are numerous reports of crashes from people trusting the tracking modes and OA to behave like the promo videos. You're far from alone in this situation.

aeciolemos · Dec 15, 2023

Luckyguy9 said:
What was the damage to the drone?

Front left arm broken on the hinge. The rest of the drone seems ok, I didn't see anything else wrong with it.

aeciolemos · Dec 15, 2023

MS Coast said:
The drone follows you in a position relative to your motion, not a compass direction or a position relative to your body. You may have walked a bit to the left along the path relative to your overall direction so that the drone moved to the right and encountered a tree branch.

DJI really does its customers a disservice with their promotional materials by suggesting that the tracking modes and obstacle avoidance can follow a person in very complex environments. There are numerous reports of crashes from people trusting the tracking modes and OA to behave like the promo videos. You're far from alone in this situation.

I guess it is a very valuable lesson learned. I thought the drone would stay to my left but I guess it deviated and didn't sense the branches. I will be more careful with OA and tracking. I will try to have someone else always there to take control in case of problems. I guess I can't trust it as I thought I could and yes, I agree, the promotional material makes it seems so easy.

Thanks for the insight.

Yorkshire_Pud · Dec 15, 2023

aeciolemos said:
Front left arm broken on the hinge. The rest of the drone seems ok, I didn't see anything else wrong with it.
View attachment 171049

I'm going to ruin your day here but I am pretty sure the arm is not broken, the pivot's base-plate is broken and as far as I am aware that is well within DIY-repair range.
You simply undo the 1 or 2 screw that are holding the remnants of the pivot inside the arm, extract those remnants then remove the three screws holding the remains of the pivot's base-plate to the drone's shell and remove those remains.
You then fit a new pivot to the shell, refit the 3 screws holding the pivot to the shell, put the arm back on the pivot and refit the 1 or 2 screws that secure the arm to the pivot.

That said, if you had cause to send the drone in at a later date and DJI detected a pattern pivot your warranty & care refresh would likely be invalidated.
Besides, DJI may spot damage you haven't notice and that is very easy to do if it is your first repair job.
So, all in all, it's probably as well you sent it in, besides there's a fair chance you will get a new drone back. The pivots are like this though this advertised as a mini 3 pivot.

MS Coast · Dec 15, 2023

aeciolemos said:
Front left arm broken on the hinge. The rest of the drone seems ok, I didn't see anything else wrong with it.
View attachment 171049

The joint ahead of the left rear arm shouldn't have a gap like that. There may be some problems in that area, too.

aeciolemos · Dec 15, 2023

Yorkshire_Pud said:
I'm going to ruin your day here but I am pretty sure the arm is not broken, the pivot's base-plate is broken and as far as I am aware that is well within DIY-repair range.
You simply undo the 1 or 2 screw that are holding the remnants of the pivot inside the arm, extract those remnants then remove the three screws holding the remains of the pivot's base-plate to the drone's shell and remove those remains.
You then fit a new pivot to the shell, refit the 3 screws holding the pivot to the shell, put the arm back on the pivot and refit the 1 or 2 screws that secure the arm to the pivot.

That said, if you had cause to send the drone in at a later date and DJI detected a pattern pivot your warranty & care refresh would likely be invalidated.
Besides, DJI may spot damage you haven't notice and that is very easy to do if it is your first repair job.
So, all in all, it's probably as well you sent it in, besides there's a fair chance you will get a new drone back. The pivots are like this though this advertised as a mini 3 pivot.

Agreed, since it is brand new, under warranty and with Care Refresh, I just sent it in just in case there was more damage that I did not see. I will wait for their repair report and see. I think they might send a new drone. I was going to use the express, but the customer support representative told me, since it was in automated mode, to send it in for inspection becvause if they determine it was not my fault, they won't charge me or use the Care Refresh. So worth the wait, I guess. Back to my Mini 2 - luckily I had not sold it yet!

aeciolemos · Dec 15, 2023

MS Coast said:
The joint ahead of the left rear arm shouldn't have a gap like that. There may be some problems in that area, too.

That is what I feared and preferred to send it in. If it was my Mini 2, I would probably just repair it myself, but this is brand new, so best leave it to DJI to refurbish or send me a new one.

Yorkshire_Pud · Dec 15, 2023

aeciolemos said:
Agreed, since it is brand new, under warranty and with Care Refresh, I just sent it in just in case there was more damage that I did not see. I will wait for their repair report and see. I think they might send a new drone. I was going to use the express, but the customer support representative told me, since it was in automated mode, to send it in for inspection becvause if they determine it was not my fault, they won't charge me or use the Care Refresh. So worth the wait, I guess. Back to my Mini 2 - luckily I had not sold it yet!

It is sensible to have at least one back up drone ........ that's my excuse and I'm sticking to it.

Felix le Chat · Dec 16, 2023

aeciolemos said:
Ultimately, I want to learn what not to do. I clearly did something wrong there and I don't know why it crashed.

I had seen this video and it seems to deal well with branches and twigs, contrary to my suspicions.

Maybe the colours are the clue, this video was in very nice, green woods, not the monochrome area I was in.

In the video you tagged, the drone crashed itself by doing exactly what you experienced: it shifted from the relatively safe route it had been instructed to favour and 'decided' to head straight into a bush to the right. As already stated, O/A is okay for the big stuff. Even then I'd never trust it fully.

Kenji_Tulsa · Dec 16, 2023

aeciolemos said:
Thank you, understood. I had the same impression, reading the logs. Nothing much there. Also, lesson learned on obstacle avoidance. Big things, sure, trees, not safe.

I just bought a Mini 4 Pro haven't flown it yet. Thanks for sharing some really valuable data for a newbie like me.

mswlogo · Dec 16, 2023

Since it was in follow me mode (not fast) and no mention of wind and not recording. Was that battery drain rate normal?

smbishop · Dec 16, 2023

Ian in London's last 3 videos go over OA. He has settled on 'by-pass' and "nifty - on". These are the settings I am currently using as well.

bobbydoug · Dec 16, 2023

aeciolemos said:
Hi everyone,

I was having so much fun flying my new Mini 4 Pro. I love everything about it. I watched countless videos of people having it follow them, avoiding all types of obstacles.

I had obstacle avoidance on, I was flying it relatively close to me, I engaged active track and I told the drone to stay at my 7-8 o'clock and follow. I started walking (I forgot to hit the record button) and after some 2 min, I hear the crash and see the drone in the grass.

I have no idea why it would crash since my left was clear of obstacles, except a few light poles, and I did tell it to stay to my left, since there were trees to my right. It is a pitty the camera was not recording (nor was I screen recording). I uploaded the logs and here is the link:

I have sent it back to DJI under both warranty and care refresh for their investigation. However, I wanted to know more before they come back to me.

Any comments are welcome.

Ice on your rotors? Just a guess based on temp and humidity.

RodPad · Dec 16, 2023

@Yorkshire_Pud
"It is sensible to have at least one back up drone ........ that's my excuse and I'm sticking to it."
Thumbswayup

Rod ..

Meta4 · Dec 16, 2023

bobbydoug said:
Ice on your rotors? Just a guess based on temp and humidity.

Ice on props results in a drone not being able to hold altitude or climb.
It sinks.
It doesn't fly off in random directions and crash into obstacles.

Dmcvey · Dec 16, 2023

Gravity

mswlogo · Dec 16, 2023

Meta4 said:
Ice on props results in a drone not being able to hold altitude or climb.
It sinks.
It doesn't fly off in random directions and crash into obstacles.

Although I think it was too warm for ice. It doesn’t look like it flew off in random directions.

Be nice to know if it was one motor or multiple motors.

HoozierDroneDaddy · Dec 16, 2023

You mentioned light poles, and trees, but you did not mention if there were any fine wires to the poles or other small wires in the area that you may not have seen. A common crash is drone hitting wires whether they be phone, electric, or otherwise. I have prechecked areas prior to flights and sometimes there are very thin wires that you cannot see unless your right up under them. A suggestion would be to go back and look to see if there are any you might have missed where you found your drone. If so, you may have your answer.