Survived a collision - a lesson learned!

pjnorris · Apr 4, 2017

I had a near miss last weekend with my Mavic Pro, with a tree!

1) Make sure RTH altitude is higher than the average tree. 30m wasn't enough.
2) Ensure you have smart RTH enabled, so the Mavic will attempt to retrace it routes (Edit: not factually correct - see my post reply below)
3) Ensure front sensors are enabled with RTH...

Otherwise this could happen, missing a lug on one prop and the branch sliced the other.

As for the footage - I had no idea the drone collided with the branch until I was editing it at home!

I consider myself lucky this time, and I have made sure the settings are set appropriately.

I hope someone can learn from my mistakes!

YngveN · Apr 4, 2017

Whoa, lucky you. And amazing job by the Mavic to keep flying after that.

Good tip, but for 2. the Mavic will not try to retrace its route. It will however try to avoid obstacles that it is able to sense.

Good chance it would not have sensed the smal branches in top of the trees.

pjnorris · Apr 4, 2017

YngveN said:
Whoa, lucky you. And amazing job by the Mavic to keep flying after that.

Good tip, but for 2. the Mavic will not try to retrace its route. It will however try to avoid obstacles that it is able to sense.

Good chance it would not have sensed the smal branches in top of the trees.

Ahh, looking in to this 'Smart Return to Home' feature a little further now, if enabled, it will RTH if battery gets too low. If disabled, then it ignores the battery warning and eventually land when battery is critical. Thanks for clarifying, and yes, agree that the sensor probably not spotted that 'twig'.

Anthonyk · Apr 4, 2017

I would make sure that missing blade tab isn't still in the motor.

Jim747 · Apr 4, 2017

Thanks for the video. Reminded me of the old Timex watch commercial...takes a lick'n and keeps on tick'n.

pjnorris · Apr 4, 2017

Anthonyk said:
I would make sure that missing blade tab isn't still in the motor.

I'm guessing not as I flew it for another full battery after collision which I was clueless to! I checked the drone after I got home and saw the footage. Double checked it to make sure motors are free and replaced all the props just in case the others took a knocking.

Thanks.

JLane · Apr 4, 2017

YngveN said:
Good tip, but for 2. the Mavic will not try to retrace its route.

I believe I've seen @msinger mention that the Mavic does have the feature of retracing it's route a little bit, but this would only happen in the case of an RTH due to RC signal loss, not normal RTH. The logic being that if it flies back on the route, there's a good chance it will regain RC connection.

AnchorageAk · Apr 4, 2017

Man, you where low over those trees. Good job of flying, almost.

pjnorris · Apr 4, 2017

AnchorageAk said:
Man, you where low over those trees. Good job of flying, almost.

Wasn't my intention! It was in RTH mode and I had no visibility until it got back in range! [emoji41]

YngveN · Apr 4, 2017

JLane said:
I believe I've seen @msinger mention that the Mavic does have the feature of retracing it's route a little bit, but this would only happen in the case of an RTH due to RC signal loss, not normal RTH. The logic being that if it flies back on the route, there's a good chance it will regain RC connection.

The logic is solid, and it would be a good feature. Certainly it is also technically doable, and in at least two of the crashes I have read about here, it probably would have regained RC connection and saved the AC.

But I would like to have this confirmed. All I I have seen on RTH suggest the Mavic just heads straight for the home point.

Kawboy12R · Apr 4, 2017

In response to the poll, I don't have a set RTH height. It's probably at either 40 or 50m most often, but I change it based on wind and obstacles. Higher than the highest point I'll be flying past. Lots of extra height is ok unless it's windy and RTH would be upwind.

dewster · Apr 4, 2017

Tree branches and thin wires are troublesome.

Tonka · Apr 9, 2017

1m = 3.28ft, 30m = 98.5ft. Jesus you have tall trees. I set mine to 30 meters normally but at new locations that I have been I scan manually first then set whatever the altimeter says. Nice recovery. I've been scouring videos of fail drone pilots and I have seen things I now know can happen. I saw a pilot fly one into a building, it was spinning out of control and the sensors kicked it and kept it flying. RTH and all. Impressive what these can take sometimes.

Texoma Drone · Aug 19, 2017

Kawboy12R said:
In response to the poll, I don't have a set RTH height. It's probably at either 40 or 50m most often, but I change it based on wind and obstacles. Higher than the highest point I'll be flying past. Lots of extra height is ok unless it's windy and RTH would be upwind.

Rule of thumb for me, RTH height is set at 250 feet!