Mavic 2 Pro Forced Landing - Sunk and Lost in Salt water.

[IansMavic]

Here's a lesson for all.

Small boats and drones DO NOT MIX.

Had our Mavic 2 Pro out on a river shooting a marine salvage. We all had to get out of the Big 30 foot Boat and into a Small 15 foot open boat.

Client still wants to cover it with the drone. So we are taking off and catching the drone in our hands.

So the technique was: It takes off from the palm of my hand, then when landing - hover in front and grab the landing strut with right hand and kill the throttles with left hand, Drone flops down and all good.

Grabbing the strut stops it avoiding the hand.

All goes well for about five or s ix launches. On the final landing, the boat is moving just a tiny bit. Just in the current.

It was late in the day - 16.45.

Drone comes in and starts to veer away each time it gets close. Does not want to come in close to the boat. Obviously not happy about the landing area. Who can blame it. 14 foot boat with four blokes in it.

Finally get it down to where my colleague can grab it. Soon as he gets a hold of the landing strut it starts to rev up like crazy, he's holding on but even with throttle all the way down the drone won't stop. In fact it is revving flat out.

The look on his face - anyway, So I fearing for his safety I just tell him to let it go and we'll have another pass. Drone goes up to about 10 feet above water and I start to get "Auto Land Messages" on the screen. All of which I say NO to. Hit the red X.

They keep coming up. Meanwhile trying to get the Drone back over the boat but it keeps beeping and giving me the Auto Land message. Each Time I hit no.

It says inappropriate Landing area or something - then, even with the left stick all the way up, quietly drifts away from the boat and methodically hovers about an inch from the surface of the water- then lands itself on the water and drops into the murky depths.

Guy driving there boat can't get near it in time. If it was at 50 feet, maybe we could have got under it but there were divers below and no way to easily manoeuvre.

Downloaded flight logs today.

The Obstacle avoided message then Auto land then Force Landing.

Plenty of battery.

So I have read it is a mixture of causes, water surface. Obstacle avoidance. Seems a bit silly that it just went into forced landing. Even with a three quarters full battery.

I'm devastated but at least nobody got hurt.

Flight data attached.

Thoughts?

Ian.

 

[MAvic_South_Oz]

Sorry for your loss, hopefully it's well and truly made its $ for you, and you can just replace and hopefully find out what happened as a learning experience.
Be an interesting analysis, look forward to seeing what happened too.

 

[Meta4]

Flying from a boat is an unforgiving environment.
As you've found, one mistake may well be the end for your drone.

On the final landing, the boat is moving just a tiny bit. Just in the current.

That's a big problem that land based flyers never experience.
When the drone was grabbed but the boat was moving, the drone fights to hold position (to get back to where it was grabbed).
Some flyers modify their Mavics so they are able to select Atti Mode and flicking to atti at the catch time prevents a fight with the drone because it won't try to hold position.

Drone comes in and starts to veer away each time it gets close. Does not want to come in close to the boat. Obviously not happy about the landing area. Who can blame it. 14 foot boat with four blokes in it.

Disabling the downward looking sensors would probably fix that issue.

Flight data attached.

Can you post the .txt file?

 

[IansMavic]

Flying from a boat is an unforgiving environment.
As you've found, one mistake may well be the end for your drone.

That's a big problem that land based flyers never experience.
When the drone was grabbed but the boat was moving, the drone fights to hold position (to get back to where it was grabbed).
Some flyers modify their Mavics so they are able to select Atti Mode and flicking to atti at the catch time prevents a fight with the drone because it won't try to hold position.

Disabling the downward looking sensors would probably fix that issue.

Can you post the .txt file?

Yes to all the above. .txt attached.

 

[IansMavic]

Now that I have a case and batteries and a host of accessories and no drone, can you actually buy a mavic pro 2 all on its' own?

If so how?

 

[Deleted member 94047]

Ouch! So sorry for your loss This looks to me like a simple case of the aircraft entering into forced landing mode because you pushed the throttle stick full down for 3 seconds while it was near its vertical low limit (near ground). That automatically triggers forced landing mode; and once the aircraft entered in to that mode, you were unable to abort it even if you pushed the throttle stick full up during the last few seconds of the flight.



I will wait for what others with more knowledge than me have to say about this though. I always thought it was possible to abort a forced landing state, looks like I was wrong.

 

[IansMavic]

Thanks very much. Shame it didn't do that when we had it in our hands.

 

[Deleted member 94047]

Thanks very much. Shame it didn't do that when we had it in our hands.

There is something in the DAT event stream log which I think is probably related to that but I unfortunately don't understand what it means.

389.140 : 21757 [L-RC]arm stop reject because of no craft fail in near history
389.160 : 21758 [L-RC]arm stop reject because of no craft fail in near history
389.180 : 21759 [L-RC]arm stop reject because of no craft fail in near history
389.200 : 21760 [L-RC]arm stop reject because of no craft fail in near history
389.220 : 21761 [L-RC]arm stop reject because of no craft fail in near history
389.240 : 21762 [L-RC]arm stop reject because of no craft fail in near history
389.260 : 21763 [L-RC]arm stop reject because of no craft fail in near history
389.280 : 21764 [L-RC]arm stop reject because of no craft fail in near history
389.300 : 21765 [L-RC]arm stop reject because of no craft fail in near history
389.320 : 21766 [L-RC]arm stop reject because of no craft fail in near history
389.340 : 21767 [L-RC]arm stop reject because of no craft fail in near history
389.359 : 21768 [L-RC]arm stop reject because of no craft fail in near history
389.380 : 21769 [L-RC]arm stop reject because of no craft fail in near history
389.399 : 21770 [L-RC]arm stop reject because of no craft fail in near history
389.419 : 21771 [L-RC]arm stop reject because of no craft fail in near history
389.439 : 21772 [L-RC]arm stop reject because of no craft fail in near history
389.459 : 21773 [L-RC]arm stop reject because of no craft fail in near history
389.479 : 21774 [L-RC]arm stop reject because of no craft fail in near history
389.499 : 21775 [L-RC]arm stop reject because of no craft fail in near history
389.519 : 21776 [L-RC]arm stop reject because of no craft fail in near history
389.539 : 21777 [L-RC]arm stop reject because of no craft fail in near history
389.559 : 21778 [L-RC]arm stop reject because of no craft fail in near history
389.579 : 21779 [L-RC]arm stop reject because of no craft fail in near history
389.599 : 21780 [L-RC]arm stop reject because of no craft fail in near history

It goes on for a while after that, the same message repeated again and again. @sar104 have you seen this before?

 

[IansMavic]

There was a suggestion because it was tilted slightly it went ape

 

[glennal]

Due to my disability with weak hands/muscles I land my mavic on top of my electric wheelchair which is reclined back and has a removable plastic white board placed on top as a landing pad. Its only about 2 foot x 2 foot so if theres wind its hard to land. What i do and what would have helped you would have been to turn off the "landing protection" option under sensors.
When you give left stick down it will lower & land no matter whats under it , with no hesitation or sensor involvment

 

[IansMavic]

Due to my disability with weak hands/muscles I land my mavic on top of my electric wheelchair which is reclined back and has a removable plastic white board placed on top as a landing pad. Its only about 2 foot x 2 foot so if theres wind its hard to land. What i do and what would have helped you would have been to turn off the "landing protection" option under sensors.
When you give left stick down it will lower & land no matter whats under it , with no hesitation or sensor involvment

Next time hey.

;-))

 

[IansMavic]

Thanks for taking the time to do that BTW. Very helpful and informative.

Ouch! So sorry for your loss This looks to me like a simple case of the aircraft entering into forced landing mode because you pushed the throttle stick full down for 3 seconds while it was near its vertical low limit (near ground). That automatically triggers forced landing mode; and once the aircraft entered in to that mode, you were unable to abort it even if you pushed the throttle stick full up during the last few seconds of the flight.

View attachment 101388

I will wait for what others with more knowledge than me have to say about this though. I always thought it was possible to abort a forced landing state, looks like I was wrong.

 

[droneloverair]

Has anybody come up with a portable landing gear that you fold open with handles below it so someone could have that up their head and the pilot land on top of it. Pilot then comes and picks up the drone.

Landing pad fold close.

 

[Deleted member 94047]

Thanks for taking the time to do that BTW. Very helpful and informative.

No worries. I am still waiting for @sar104 or @slup to confirm that is indeed what happened. And more importantly, on the possibility of aborting/exiting the forced landing state once it has been triggered. While a crash is a very unfortunate event for the pilot involved, every crash is also a learning opportunity for others.I have learned quite a lot from what is posted in this forum and this will be yet another important lesson to draw if it is indeed the case that a forced landing cannot be aborted once initiated.

 

[MAvic_South_Oz]

Has anybody come up with a portable landing gear that you fold open with handles below it so someone could have that up their head and the pilot land on top of it. Pilot then comes and picks up the drone.

Landing pad fold close.

I've thought about this for on water ops form boats etc, after reading so many mishaps, and various threads of people wanting to fly from their boats.

A landing pad of thin plywood, say 2' dia for a M2 size drone.
Cover the entire top in hook velcro, have landing skids on the drone, fit loop velcro to the skids really well.

I thought firstly hand launch, fairly easy in most cases on all but rough water.
Landing protection off.

The pilot should bring the drone in to head height and keep pace with the boat while the catcher brings the landing pad up and under.
Once the drone touches the pad, at least it'll stay put as the motors are shut down by csc or left stick down by the pilot.

 

[slup]

No worries. I am still waiting for @sar104 or @slup to confirm that is indeed what happened. And more importantly, on the possibility of aborting/exiting the forced landing state once it has been triggered. While a crash is a very unfortunate event for the pilot involved, every crash is also a learning opportunity for others.I have learned quite a lot from what is posted in this forum and this will be yet another important lesson to draw if it is indeed the case that a forced landing cannot be aborted once initiated.

Have tested this with aborting a forcelanding with my own Mavic Air ... no problem at all to stop it, just 1sec of decisive positive throttle & it aborts & ascends. See here below ... first purple area (forcelanding initiated by max negative throttle longer than 3sec) is aborted. The second one I let it touch down.



Here similar chart from the OP txt log ... note the green area with autolanding before forcelanding is initiated by negative throttle. Wonder if that messed thing's up & that's why it wasn't possible to abort the landing?

 

[Deleted member 94047]

Thanks slup; that is one test I will also do.

Here similar chart from the OP txt log ... note the green area with autolanding before forcelanding is initiated by negative throttle. Wonder if that messed thing's up & that's why it wasn't possible to abort the landing?

Could it be that the FC interprets negative throttle while AC is in autolanding mode as confirm landing? But even then, I don't quite understand why it failed to respond to the positive throttle the pilot applied immedietly afterwards (with in a second after AC enters forced landing mode); yours apparently responded so ... I am confused! This needs further testing.

 

[naiku]

Has anybody come up with a portable landing gear that you fold open with handles below it so someone could have that up their head and the pilot land on top of it. Pilot then comes and picks up the drone.

Landing pad fold close.

I have seen this product somewhere for sale, but I cannot remember where I saw it now, but it is exactly what you are describing, a foldable landing pad that you hold out for the drone to land on. Here you go... took a few minutes to find it.... New Product Launch - Phantom Rain ! Lunar Landing Pad System :]

 

[jpzend125]

Next time hey.

;-))

I too am sorry for your loss. I dropped mine in saltwater this past January. I had DJI insurance and while they won't replace it without getting the damaged bird, they did sell me a M2Z with battery, no other accessories, for a 15% discount. Needless to say, I am leery of flying over water.

 

[Chrislaf]

Sorry for your loss of such an expensive drone.

I had a similar experience with my Spark. Was testing take-off and landing from my kayak In calm conditions. The first attempt went well with no problems, however on the second attempt the Spark didn’t want to land on my hand. After numerous attempts it went into low battery landing. Luckily I was in shallow water near shore so I could quickly get out and land it in my hand.

I plan on testing again once the water/weather warms up with the sensors off. My trails on land with the sensors off have been tricky too - it comes down fast if you are not careful and the hover is way less steady. Going to try just grabbing out of the air but this is tricky too on the compact drones (and a moving boat) since the spinning props are close to the hands.

Anyway hopefully DJI can give you a discount on a new one.

Chris