Hello all,
My new mavic air crashed today into a bridge.   I got the Mavic Air in part due to its collision avoidance features.   I had the obstacle avoidance turned on and everything was going fine until the drone got under the bridge and started to drift left.  When it did, the drone hit the bridge pylon and crashed into the water.   Unfortunately I cannot recover it since it likely got washed downstream.  I don't know why it started drifting.

I am posting a video here of the flight.  I would welcome any comments - also had ND-PL filter on the lens so I would welcome comments as to why the video didn't look so great before it got under the bridge.

Regretfully, I purchased DJI Care refresh, but that won't do me any good since the drone cannot be recovered.

the drift occured because of the water movement confused the visual positioning system (VPS) as well as may have been little bit of wind or prop turbulence as you approached the bridge..   then once gone under the bridge, no GPS, even if still in GPS mode on the app..  


on top of this, you were flying under a bridge that has a very narrow gap between water and the bridge..  so very very little room for error.  im going to go out on a limb here and guess your newer to flying these drones... and flying in such a tight spot requires skill and experiance.  and actually much easier to fly under larger structures...


the avoidance features are nice, but they should not be relied on, they are there to assist you not to completely take over.. like all self driving cars we seen still getting into wrecks and fatalities..  same reason.  rely on it too much and it will eventually fail you.. mostly fail you because it is an assistance program, ...same with drones....

the crash occurred when you went sideway.. there is no side sensors. sorry to hear about out your loss, i crashed mine in a tree when moving sideway

That's a crappy way to learn a lesson. Sorry that happened.

Hi StormyAcres, we're sorry to read the accident. If the unit is under warranty period, please kindly contact our support and start a case: https://www.dji.com/support We'll arrange data analysis and offer you a proper solution based on the data analysis result.

Unfortunately this is just going to have to be a hard lesson for you.

Collision avoidance is there as a safety feature, not to be a replacement for flying abilities. The moment you said you went under a bridge, that pretty much gives one reason why it would start to drift. No GPS is one factor to remember. You need visibiltiy of the sky to maintain a decent GPS signal. Once it has no reference to where it's actual position is meant to be, there are no side sensors to save you if it drifts to the side with a bit of wind.. or in the case here, what appears to be the downwards poitioning sensors taking over.

Ouch, sorry for your loss. Hope your back flying soon.

Posting your flight log here would give us some idea of what went wrong. You can find instructions on how to do this at the DJI Flight Log Viewer and then post the resultant link here. Some of the sharper folks here can give you some insight if they spot something.

sorry for your loss, bright side is that on some occasions DJI came through for some, hopefully you will be one,  keeping my fingers crossed, but I do agree with here for the Breer

Above is correct. The drone is so stable because PDF GPS. Under a bridge, no GPS. Without GPS, it's flying by your control, which is subject to drift from wind or downward sensors trying to sense a pattern on moving water to hover over. Dangerous stuff to fly under a bridge and over water. Sport mode and quickly get through may work, but hovering under slowly ends this way. Sometimes a drone will go up instead of drifting to the side to try and hold position. Little help now, but the manual warns not to do this.

Sorry to read that - fingers crossed you are back up soon

Been there done that and it really sucks. Really sorry man.

No GPS signal under bridge and low above moving water surface equal to lost control and crash.

You kind of asked for this to happen dude... so many mistakes that I prefer don't say more....

ro_flyer Posted at 2018-9-15 07:23
You kind of asked for this to happen dude... so many mistakes that I prefer don't say more....

I'm not really sure why you said anything at all.   If you have helpful information to share, then please do, but  saying I asked for it really doesn't offer any information.    Sorry "captain" that I'm new to drones and was just trying to get some interesting footage to share.   We can't all be as experienced as you right out of the box.

Another thing to consider is the bridge interfering with the compus due to all of the metal.

I would do what the DJI bot said to do above. Worst case scenario is they do t help but there is always that chance.

StormyAcres Posted at 2018-9-15 07:56
I'm not really sure why you said anything at all.   If you have helpful information to share, then please do, but  saying I asked for it really doesn't offer any information.    Sorry "captain" that I'm new to drones and was just trying to get some interesting footage to share.   We can't all be as experienced as you right out of the box.

Beer probably gave the best guess on what happened but the "captain" was also correct. In addition to the other things mentioned I'm guessing you didn't have a good view on the drone and were flying solely based on the camera feed. By the time the drone took off to the side it was too late for an inexperienced pilot to react.

Hi all , I am a 64yo Nanny looking at purchasing Mavic Air Drone Fly Air more. My question is, I believe you need wifi but can you use a mobile data wifi device or do you need to use a phone with a data sim. As you can see, you have a recycled virgin here and before I buy this device I need to know how well I can use this in places that are remote in outback Australia.

djiuser_6RwBsSSTbfix Posted at 2018-9-15 13:22
Hi all , I am a 64yo Nanny looking at purchasing Mavic Air Drone Fly Air more. My question is, I believe you need wifi but can you use a mobile data wifi device or do you need to use a phone with a data sim. As you can see, you have a recycled virgin here and before I buy this device I need to know how well I can use this in places that are remote in outback Australia.

You do not need data or cell connection when flying at all, even better not to have it. You only need internet connection before going into the field for updating everything that needs an update.

I am very sorry for your loss indeed! The root causes have been explained by others here above, thus I do not need to reapeat and throw more salt into the open wound. But I strongly recommend you to follow the advice given by DJI Susan in post 5# and open a support ticket. You have nothing to lose, to the contrary, they might even offer you some discount for a replacement drone. I have seen many similar cases.

Where was the pilot when the drone began to drift sideways?  Easy to correct with remote controller stick deflection.  Relying on the autopilot to keep the drone safe while the pilot was asleep at the sticks has put many a drone in the water.  This guy accurately placed a moving drone under railroad cars without any GPS stabilization simply by staying active on the sticks.

Sorry for your loss.
Can’t you go swimming in there to retrieve the drone?
It doesn’t look that deep at all!

Fly safe all
Alex

Gunship9 Posted at 2018-9-15 14:05
Where was the pilot when the drone began to drift sideways?  Easy to correct with remote controller stick deflection.  Relying on the autopilot to keep the drone safe while the pilot was asleep at the sticks has put many a drone in the water.  This guy accurately placed a moving drone under railroad cars without any GPS stabilization simply by staying active on the sticks.

https://www.youtube.com/watch?v=YcTaRua47YQ&t=39s

Great video!
Thanks for sharing!

Another small hint: try to stay away from powerlines, there is a quite big magnetic interference around them, and this can easily effect your drone

DJI Susan Posted at 2018-9-14 18:30
Hi StormyAcres, we're sorry to read the accident. If the unit is under warranty period, please kindly contact our support and start a case: https://www.dji.com/support We'll arrange data analysis and offer you a proper solution based on the data analysis result.

Thank you DJI Susan,  I have opened a support ticket by email.  

Paul_IA Posted at 2018-9-14 19:24
Posting your flight log here would give us some idea of what went wrong. You can find instructions on how to do this at the DJI Flight Log Viewer and then post the resultant link here. Some of the sharper folks here can give you some insight if they spot something.

Log uploaded - here:  Crashed drone log
Clearly switched to ATTI mode for sure.

Weak GPS signal. Aircraft is in Attitude mode and hovering may be unstable. Fly with caution.
U were in ATTi mode!

Sorry for your loss. The reasons are clear and were stated above. Please do not repeat them anymore

Gunship9 Posted at 2018-9-15 14:05
Where was the pilot when the drone began to drift sideways?  Easy to correct with remote controller stick deflection.  Relying on the autopilot to keep the drone safe while the pilot was asleep at the sticks has put many a drone in the water.  This guy accurately placed a moving drone under railroad cars without any GPS stabilization simply by staying active on the sticks.

https://www.youtube.com/watch?v=YcTaRua47YQ&t=39s

Very impressive! But let’s not kid ourselves - there’s no way that the majority of the general hobby flyers on this forum are going to achieve ANY of that standard of flying!

The water is so brown s it's really hard to recover it.  Maybe the water already caused its malfunction which made retrieval even harder. Maybe you can use remote control underwater camera to see its location in order to identify where to get it. good luck.

StormyAcres Posted at 2018-9-15 17:14
Log uploaded - here:  Crashed drone log
Clearly switched to ATTI mode for sure.

Thanks for posting the log. Sorry for your loss, but hopefully you'll find a way to retrieve the drone, replace it and lesson learned. Flying under the bridge is like flying into a metal box. No way for GPS to work in that environment.

perline Posted at 2018-9-16 02:06
The water is so brown s it's really hard to recover it.  Maybe the water already caused its malfunction which made retrieval even harder. Maybe you can use remote control underwater camera to see its location in order to identify where to get it. good luck.

The sad thing is I'm a scuba instructor and if I were not on crutches after leg surgery I would probably be in the water searching for the drone.   Unfortunately that is not possible.   This area of the river is one of the few with deeper water and fast current and the drone crashed into the area with the fastest current.  I'm not optimistic about ever finding it.

StormyAcres Posted at 2018-9-15 16:56
Thank you DJI Susan,  I have opened a support ticket by email.

I was hoping DJI would simply allow me to use my DJI Care refresh - clearly the video shows the drone crashed in the water so it can't be recovered.   So far, the email I have gotten from DJI Support says they need the drone back to use refresh.  

StormyAcres Posted at 2018-9-16 15:35
The sad thing is I'm a scuba instructor and if I were not on crutches after leg surgery I would probably be in the water searching for the drone.   Unfortunately that is not possible.   This area of the river is one of the few with deeper water and fast current and the drone crashed into the area with the fastest current.  I'm not optimistic about ever finding it.

thats a shame, well since you're a scuba instructor means probably know someone maybe willing to jump in after it to help you out... right?  maybe worth still trying...  maybe lucky and caught up on a rock or something..  just offer someone a few brewskis win or fail and maybe a cash reward if they find it..

sorry for your loss and crash. I assume you were able to get the drone back right?

I have seen many comments here and based on my experience so far, I cannot tell any difference with VS on or off over water.  I have not lost my GPS connection over water though. The drone will drift in ATT mode, [no signal to GPS] but it is very solid even still.  hope DJI helps you out

Get some more flying experience before flying this close to anything in the future  

Rich

RichJ53 Posted at 2018-9-16 15:59
sorry for your loss and crash. I assume you were able to get the drone back right?

I have seen many comments here and based on my experience so far, I cannot tell any difference with VS on or off over water.  I have not lost my GPS connection over water though. The drone will drift in ATT mode, [no signal to GPS] but it is very solid even still.  hope DJI helps you out

Hi Rich,  Unfortunately I have not been able to get the drone back - it is somewhere in the river.   Clearly I need to get some more experience so I need to get another drone.  Hopefully DJI will help me out on that one and let me use my refresh.  
This was my first day out of the house to do something after my leg surgery so I was hoping to get some nice footage over the river.   I guess I did get a nice video of the drone crash but that wasn't exactly what I was planning on....

HereForTheBeer Posted at 2018-9-16 15:53
thats a shame, well since you're a scuba instructor means probably know someone maybe willing to jump in after it to help you out... right?  maybe worth still trying...  maybe lucky and caught up on a rock or something..  just offer someone a few brewskis win or fail and maybe a cash reward if they find it..

Yeah, I am reaching out to some of my scuba friends to see if anyone wants to go on a search mission.
I'm not actively diving any more so not as much in touch with the scuba community as I used to be.

Ouch! that is how I lost my P4, but in a fast and cold moving river

InvisibleName 7 Posted at 2018-9-16 01:02
Very impressive! But let’s not kid ourselves - there’s no way that the majority of the general hobby flyers on this forum are going to achieve ANY of that standard of flying!

Not to that standard, (the example was of extreme non-GPS stabilized pilot skills) but enough to correct a drift to the side into an obstacle.  Correcting drift being the minimum skill that should be present if flying routinely in the nation's airspace.  

However, I know there should be slack given to newbies who will lose a couple of aircraft as they learn and expand their flying range/envelope.  Fly what you can afford to lose given the nature of RC model flight.  

Gunship9 Posted at 2018-9-16 17:45
Not to that standard, (the example was of extreme non-GPS stabilized pilot skills) but enough to correct a drift to the side into an obstacle.  Correcting drift being the minimum skill that should be present if flying routinely in the nation's airspace.  

However, I know there should be slack given to newbies who will lose a couple of aircraft as they learn and expand their flying range/envelope.  Fly what you can afford to lose given the nature of RC model flight.

kind of agree, it is a basic skill everyone should know, or at least be able to "mostly" manage.  

that being said i dont think lack of GPS was the issue here..i flown without GPS indoors and even outdoors and using "Position (vision)" mode is totally stable and easy.. i think the issue where was the vision system was confused he was so close to water, the downfiring camera  and sensors was tracking the water and compensating for that movement.. it gets confused because part of what vision system is doing is correcting for aircraft drift, and moving water confusing the aircraft into thinking it is moving so its trying to track it..