Help!... Mavic Air dropped out of sky into lake!

[ac0j]

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Please answer my question were you flying 30 ft or below 30ft to the serface of the water.?
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I dont have a MA, but unless it has really long landing gear, I would say that he was below 1 inch in altitude over the water. If you read the previous posts.

 

[charliesRig]

Hi everyone, new to this forum but have seen some really knowledgable guys so was hoping for some assistance.

I was taking my new (24 hours old) magic air for a spin, went over a lake to take a photo and with over 30% power left in the battery it just dropped out of the sky... no warning. Can anyone help with why this might have happened and where I stand with DJI about a replacement?

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I dont have a MA, but unless it has really long landing gear, I would say that he was below 1 inch in altitude over the water. If you read the previous posts.

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Were did you read he was below 1 inch in altitude over the water.??
and yes I read the previouse threads

 

[ac0j]

The few posts that said it actually touched in the water, and he tried to accelerate out of it and failed.
Post #18 and #19, were the latest, but @sar104 had figured that was what happened many posts prior to those.

 

[charliesRig]

The few posts that said it actually touched in the water, and he tried to accelerate out of it and failed.
Post #18 and #19, were the latest, but @sar104 had figured that was what happened many posts prior to those.

Roger That ....
another "Sky is falling Because I was stupid thread"
It didn't fall out of the sky as much as it touched down on the water and could not recover from a water "Hover situation"

 

[ac0j]

Roger That ....
another "Sky is falling Because I was stupid thread"
It didn't fall out of the sky as much as it touched down on the water and could not recover from a water "Hover situation"

I guess I dont know if he piloted it down to that level, the "falling" may have happened right before that? I am no Sar104 when it comes to decoding all those colored wavy lines...

 

[jmillingworth]

I guess I dont know if he piloted it down to that level, the "falling" may have happened right before that? I am no Sar104 when it comes to decoding all those colored wavy lines...

It was around 1.5 metres above the water moving forward, not up or down). It suddenly dropped and splashed before sinking. It wasn’t lowered into the water, it was a sudden drop, as if it lost all power.

 

[jmillingworth]

Ah - so it was in the water at the end of the log. In that case, if you look at the graph above, I suspect it splashed down at around 771 s - due to the down throttle that you applied at 770 s. The accounts for the unusually steady pitch values at that time. In that case there obviously was no power disconnect and the log ends because it sank. Does that seem consistent with what you saw?

It was flying level at the time, for the final (approx) 4 - 5 seconds of flight, just forward motion... then dropped into water. It still had visible power for probably around a further 3 seconds or so once it was visible on the surface of the water.

 

[jmillingworth]

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Please answer my question were you flying 30 ft or below 30ft to the serface of the water.?
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At the time it was around 1.5metres above the water I would say. It also dropped like as if it had no propellers spinning... it seemed to drop visibly faster than if you pulled down on the stick! There was power to it however as when it was in the water I tried to lift off with no success.

 

[CCDD]

Your 30% battery over water is not the issue, the minimal altitude likely was. Nearly every flight I take is over water, often times 2 or more miles out. I’ve never turned off any sensor however, I never fly low enough to run into those issues. One can’t accurately visually measure altitude of a quad once it’s more than 100 yards away therefore you’d need to watch the telemetry readings on your remote or FPV. The Mavic often fluctuates in altitude a bit and readings can be off a bit as well. This in my opinion was pilot error as you likely flew too close to lake and caught one of the arms in the water.

 

[rfc]

Can’t sudden discontinuities in the GPS calculated position (particularly in altitude), cause sudden shifts?
Like perhaps the A/C drops one satellite for another, and makes an adjustment?

 

[sar104]

It was flying level at the time, for the final (approx) 4 - 5 seconds of flight, just forward motion... then dropped into water. It still had visible power for probably around a further 3 seconds or so once it was visible on the surface of the water.

That is not what the data indicate. Looking at the end of the flight, there are only a few possibilities. I've made the important traces bold:



At 765 s the aircraft is flying level with forward elevator. At 767 s you centered the elevator and applied down throttle. At 770 s the aircraft has stopped forward motion and is descending. By 773 s you have stopped applying down throttle and the aircraft is fully stationary. From your previous description it seemed like it might be in the water at that point, but maybe not - it's close though. At 775 s you applied forward elevator again, going to full at 777 s. The aircraft accelerates to around 1.4 m/s, so it is not in the water. No change in height is recorded at this time. Then at 779.5 s you abruptly center the elevator, producing the extreme pitch excursion from -37° to +40° that I mentioned before. The aircraft begins to decelerate and you apply full up throttle at 781 s - then the record ends.

So nothing about those data indicate steady horizontal flight followed by a sudden, uncommanded drop. If the motors were on when it hit the water then this is likely just a loss of height due to the sudden stop - a common event, followed by signal loss as the aircraft antenna submerged. The other possibility, as I mentioned before, is a dislodged battery, but that now seems less likely.

Looking at that graph and my description of what it says, can you comment on how the features described relate to what you did and saw?

 

[mlee]

A friend of mine lost his Mavic Pro in a lake and fished it out 48hrs later. After a tear down and a couple days drying out it flys perfectly. Lens needs to be replaced due to fogging but that's basically it.

 

[timlyg]

Did you have to pay them divers?

 

[Kingdark]

I'm curious too. Did you get the drone ensured that dji offers?

 

[jmillingworth]

Your 30% battery over water is not the issue, the minimal altitude likely was. Nearly every flight I take is over water, often times 2 or more miles out. I’ve never turned off any sensor however, I never fly low enough to run into those issues. One can’t accurately visually measure altitude of a quad once it’s more than 100 yards away therefore you’d need to watch the telemetry readings on your remote or FPV. The Mavic often fluctuates in altitude a bit and readings can be off a bit as well. This in my opinion was pilot error as you likely flew too close to lake and caught one of the arms in the water.

Thanks for comment, however it was around 50 metres from me and just below my eye level so didn't catch the water, we saw it physically 'drop'

 

[jmillingworth]

Did you have to pay them divers?

They didn't want paying!.... I offered but they insisted that they wouldn't accept it. So I donated some money to their Scuba Club and get them a cash to buy themselves a beer which they finally took. A great bunch of guys that I was lucky to find. Still nice people in the world

 

[jmillingworth]

I'm curious too. Did you get the drone ensured that dji offers?

I do have the DJI Care Refresh which is something.... however I don't feel I should have to use it which is why I wanted to get some expert advise as to what the flight data reveals.

 

[jmillingworth]

That is not what the data indicate. Looking at the end of the flight, there are only a few possibilities. I've made the important traces bold:

View attachment 43791

At 765 s the aircraft is flying level with forward elevator. At 767 s you centered the elevator and applied down throttle. At 770 s the aircraft has stopped forward motion and is descending. By 773 s you have stopped applying down throttle and the aircraft is fully stationary. From your previous description it seemed like it might be in the water at that point, but maybe not - it's close though. At 775 s you applied forward elevator again, going to full at 777 s. The aircraft accelerates to around 1.4 m/s, so it is not in the water. No change in height is recorded at this time. Then at 779.5 s you abruptly center the elevator, producing the extreme pitch excursion from -37° to +40° that I mentioned before. The aircraft begins to decelerate and you apply full up throttle at 781 s - then the record ends.

So nothing about those data indicate steady horizontal flight followed by a sudden, uncommanded drop. If the motors were on when it hit the water then this is likely just a loss of height due to the sudden stop - a common event, followed by signal loss as the aircraft antenna submerged. The other possibility, as I mentioned before, is a dislodged battery, but that now seems less likely.

Looking at that graph and my description of what it says, can you comment on how the features described relate to what you did and saw?

Thanks again for detailed reply and highlighting various bits. So from the above I would add that I think the abrupt entering of the elevator may have been when I saw it in hit the water.... as from what I remember the only action I did after that was apply full up throttle to try and get it climb out of the water so I think the extreme pitch excursion may have been the point it smacked into the water??

 

[sar104]

Thanks again for detailed reply and highlighting various bits. So from the above I would add that I think the abrupt entering of the elevator may have been when I saw it in hit the water.... as from what I remember the only action I did after that was apply full up throttle to try and get it climb out of the water so I think the extreme pitch excursion may have been the point it smacked into the water??

No - that's definitely not the case, because the pitch excursion and deceleration that follows the elevator being centered could only have occurred while airborne. Application of the throttle was 1.5 seconds later. At this point I'm pretty certain that the drop was simply caused by the sudden deceleration. It's very hard for the aircraft to hold altitude perfectly when pitched at 40°, and some loss of altitude is very common. Pilots have often commented on that, and a number of crashes have occurred because of it.

 

[HWCM]

30% is equivalent to a 100% chance of dropping the drone on the lake so next time apply some smart moves okay

This is 100% not true. Stop making stuff up.