How does ATTI work exactly as had my first crash using it?

Bunraku · Jul 10, 2018

Hi

I've lots of flights with my Mavic Pro using GPS mode and never had an issue.
However I went to a place called the Devils Pulpit in Scotland.
Its like a moss covered gorge with an orange/red river going through it. Believe me when I say there is nothing like it anywhere else in Scotland like it. It's like something from Jurassic Park.I'd went there 3 weeks ago and it was too busy with tourists and was heaving. So I want back last Sunday and left my home at 0630 and got there before 0800. Only 1 or 2 people there compared to the 30-40 the previous time.

So I get my Mavic out and only get 5 satellites. I've never had this before and wasn't expecting this as I have seen other videos of people flying DJI drones there. It says I can fly using ATTI mode and to fly with caution etc. That's annoying as I wanted to use Tripod Mode and it says it's unavailable with so few satellites.

So I've driven to this place twice and it's a 100+ mile round trip each time to try and get it droned so of course i'll still fly. So I fly my drone slowly about 30 ft away from me and level. Ok it's now getting close to the left hand side of the gorge. So I pull it back. So to me it should have come back exactly in a straight line back to me. However it didn't and started to go to the right for no reason. As you can see in the video I have included this all happened in the space of less than 2 seconds and my reaction was to turn it rather than strafe it left. Any way the end result as 3 broken propellers and my Mavic covered in mud and bits of moss. Of course I wanted to be sick and just packed up and left. So after all that driving and getting down there I was probably there less than 10 minutes before I headed home. Anyway after a clean up and changing all the props the Mavic seems ok.

So 2 questions.

1) Looking at the video what happened? I've heard prop wash might have pushed it off the left wall onto the right wall??

2) This place is quite impressive and at risk to my drone I am prepared to go back for a 3rd try. So exactly how does ATTI mode work and how can I avoid a repeat? I know its possible as someone saw my crash video and said they had flown their Mavic there in ATTI mode?

Thanks

TrayBoz · Jul 10, 2018

You're not getting many Sats locked because of the small confined space (confined by rock).
The mavic is forced to fly in ATTI because it can't get many Sats locked.
In ATTI mode, almost anything can keep it from staying put or flying level/stable. - prop wash, a breeze, a slightly bent prop, a bad attitude, etc.

Personally, I would definitely NOT try to fly my MP in ATTI mode in a confined space like that.
Either my balls are too small or my brain is too big.

Buy a good pair of rain-boots and walk the mavic through there while holding it in your hand.
Much less likely to hit a wall.

AeroMirage · Jul 10, 2018

Glad it worked out OK.
That is one pretty setting!!
Atti mode is very difficult to fly in. Especially in a confined area.
I wouldn't try it again, as you would likely have the same result.

Mossiback · Jul 10, 2018

Bunraku said:
...So 2 questions.

1) Looking at the video what happened? I've heard prop wash might have pushed it off the left wall onto the right wall??

2) This place is quite impressive and at risk to my drone I am prepared to go back for a 3rd try. So exactly how does ATTI mode work and how can I avoid a repeat?...

I'm glad it did not suffer much damage. You dodged a bullet there. In regards to your questions:

In Atti mode you can be moved by a breeze that could be caused by the props. There is prop wash and prop vacuum (not sure of the term) that can really push or pull you around. Flying indoors you can get sucked to the ceiling if you get too close.
In Atti mode there is nothing to keep you positioned besides your flying talent and the bottom facing cameras and sonic sensors which can have problems over water and above a certain height. You can try a $15 (US) set of prop guards. They work well to bounce off an object but can also get hung up on them. I would not consider such a tight run without them.

RayOZ · Jul 10, 2018

As far as I know, in ATTI mode, you constantly need to be in control of your drone. If you move forward, and let go of the stick, it'll continue to drift forward until you pull the stick back. If a breeze blows, you need to move the sticks yourself to keep it in position. If you fly too close to the wall, the wind generated by the props will reflect back and push the drone in the other direction, so you need to compensate for that yourself. This is full manual control, and require a lot of practice.