First crash... Important lesson learned..

Tommygun45 · May 24, 2017

Maybe this will be a useful reminder for someone. Long story short I had someone ask me to do a real estate video of the interior of a house. Me, not having a gimbal or any other kind of stabilized rig figured, huh, I bet my Mavic could do this. So I ran through some tests and flew it around my house and it is amazingly stable in tripod mode, plus the footage looked quite good. I knew to disable the proximity sensors and of course the automatic reverse thing it does. But I forgot something.

Anyways I went to the shoot and started filming outside. Then I went inside. The house was enormous so there was enough space to move around safely. But then I made a terrible mistake. Trying to eek out some extra battery life I allowed the battery to get to a point around 15%. At this point the Mavic entered an automated return to home sequence. The Mavic became completely unresponsive to the remote controller, and in a matter of seconds, started to rise to its predetermined altitude for the RTH sequence. Needless to say the ceilings were not 50m high.

Obviously what happened next was not good. The Mavic hit the ceiling, went sideways and hit a wall and was in a completely vertical orientation, but somehow righted itself and began to hover again. At this point I thought I might have control again so as I looked down to my iPad to try to disable RTH the Mavic took off again. It hit the ceiling one more time, bounced and ran into another wall. This time its orientation was vertical but the body was towards the interior of the room. The motors went full throttle and after about 1-2 seconds one of the propellers caught, and the whole rig ninja starred itself into the ground.

At this point I may or may not have shat myself. However, upon doing a thorough inspection of the area, nothing was wrong. The walls and the ceiling, although having just been painted, were literally completely free of any kind of noticeable marks. The Mavic had damage to all propellers, and they all had some stucco kind of paint on them. One was completely shattered but the others were just fractured. I replaced the props, and she flies like new again, somehow. I am actually getting smoother footage than I was before. Go figure.

The ironic thing is that feature saved me a few months ago. I was having the Mavic hover in the sky over us at night when we were snowmobiling to record some footage. Due to wind or something it flew off a few thousand feet. When I went to check the controller and iPad its distance was over 2300 feet away and its battery was around 30%. At that instant my iPad died and I had no way to control the Mavic. This was in the remote mountains of Maine. After a few minutes, she appeared over head and landed on her own, right where she had taken off from.

So I guess, moral of the story, Automatic Return to Home Feature giveth, and taketh away.

Drope · May 24, 2017

Sorry to hear that man. So: we need to shut off that auto return if we fly indoors or under trees to be sure. Is that what you think? This scenario has crossed my mind but I haven't flown indoors yet. I plan to though..

Tommygun45 · May 24, 2017

Drope said:
Sorry to hear that man. So: we need to shut off that auto return if we fly indoors or under trees to be sure. Is that what you think? This scenario has crossed my mind but I haven't flown indoors yet. I plan to though..

Oh absolutely. I would actually think for most of the flying we do the automatic return to home feature should be disabled anyways. I always find it never really comes back where I need it to so I usually take over anyways. Also since the drone has no sensors above it it has no idea what it might be rising into. I am sure flying indoors is highly not recommended but I was able to pull it off wonderfully for a while, until that happened. The other scary part of flying indoors is turbulence in smaller areas. The wind from the props will buffer the little guy and send him either higher or lower. Also going over things like a table or an island will make it jump up in height. But other wise it is remarkably stable inside.

Turnerm · May 24, 2017

I guess the pause button doesn't work if it's engaged in an Auto RTH sequence?

Either way, that really sucks. Thanks for sharing as you have probably just saved another poor soul from a similar fate.

james_mav · May 24, 2017

It sounds like your drone has nine lives.

Did you ever think about filming while walking around the house with the Mavic instead of trying to fly it indoors.

adiru · May 24, 2017

Tommygun45 said:
Maybe this will be a useful reminder for someone. Long story short I had someone ask me to do a real estate video of the interior of a house. Me, not having a gimbal or any other kind of stabilized rig figured, huh, I bet my Mavic could do this. So I ran through some tests and flew it around my house and it is amazingly stable in tripod mode, plus the footage looked quite good. I knew to disable the proximity sensors and of course the automatic reverse thing it does. But I forgot something.

Anyways I went to the shoot and started filming outside. Then I went inside. The house was enormous so there was enough space to move around safely. But then I made a terrible mistake. Trying to eek out some extra battery life I allowed the battery to get to a point around 15%. At this point the Mavic entered an automated return to home sequence. The Mavic became completely unresponsive to the remote controller, and in a matter of seconds, started to rise to its predetermined altitude for the RTH sequence. Needless to say the ceilings were not 50m high.

Obviously what happened next was not good. The Mavic hit the ceiling, went sideways and hit a wall and was in a completely vertical orientation, but somehow righted itself and began to hover again. At this point I thought I might have control again so as I looked down to my iPad to try to disable RTH the Mavic took off again. It hit the ceiling one more time, bounced and ran into another wall. This time its orientation was vertical but the body was towards the interior of the room. The motors went full throttle and after about 1-2 seconds one of the propellers caught, and the whole rig ninja starred itself into the ground.

At this point I may or may not have shat myself. However, upon doing a thorough inspection of the area, nothing was wrong. The walls and the ceiling, although having just been painted, were literally completely free of any kind of noticeable marks. The Mavic had damage to all propellers, and they all had some stucco kind of paint on them. One was completely shattered but the others were just fractured. I replaced the props, and she flies like new again, somehow. I am actually getting smoother footage than I was before. Go figure.

The ironic thing is that feature saved me a few months ago. I was having the Mavic hover in the sky over us at night when we were snowmobiling to record some footage. Due to wind or something it flew off a few thousand feet. When I went to check the controller and iPad its distance was over 2300 feet away and its battery was around 30%. At that instant my iPad died and I had no way to control the Mavic. This was in the remote mountains of Maine. After a few minutes, she appeared over head and landed on her own, right where she had taken off from.

So I guess, moral of the story, Automatic Return to Home Feature giveth, and taketh away.

Sounds like this was new Mavic? What firmware were you on? If you were on one of the older firmware like 400 for example, it would have been possible to set it to 10% before it forced autoland/rth. But on the newer firmware like 700 it defaults to 16% and wouldn't let you change it downwards.

This could be a case of DJI's forced firmware with handicaps and added "safety" margins after the fact directly causing a crash. Because had you been on an earlier firmware with less handicaps then the few % of extra usage battery form 16% to 10% might have been the difference between a successful flight that ended in a good landing, and that of your crash as you entailed... Sometimes it is just a few % different, and arguable it would be said that the root cause can be attributed to DJI's decision to 1) alter and reduce the usable battery level post-sales, retroactively and after the fact 2) still advertise the same 27 flight time, hence giving counter and false indications to consumers that "nothing changed" with regards to shorter flight times 3) essentially all but force and compel users to have no other realistic option but to upgrade to these said aforementioned newer firmware with reduced flight and performance envelope capabilities etc. 4) confusing RTH inconsistency across firmware versions, which now cannot be easily canceled simply by throttling up and/or just pressing the red pause button.but DJI did not send out any advisory on this to users.

In my mind, if I was an NTSB investigator, DJI is mainly to blame here.

But for the pilots part, you should always be actively monitoring your flight, and the moment you noticed what happened you should have had an emergency contingency plan, including but not limited to pressing the red pause button, and then rapidly cycling the sports mode switch on the side to make sure it is switched to sports mode. This combination should have allowed you to cancel the RTH.
Pre-flight you should have made sure that the option to go into Sports most was set to enabled. And when you know you will be doing low flights, or esp. if indoors and possibly low battery or low gps conditions etc then consider setting the lowest possible RTH alt, and/or disable all RTH to the max extent that your firmware version will allow you to do so, and using one of those after market gimbal covers to protect the lens while still giving unobstructed view.