Lessons Learnt from splash landing

[Captain Jack]

Several months back my bird took a bath after an automatic landing caused it to try landing on water. This happened, so I'm told, because the sensors were confused over calm very reflective water. Guess it wasn't my day as I had only turned the sensors on for that flight after reading that would keep the bird from dipping so much that the blades showed on the video. Becasue I launch and retrieve from a vessel, I had always flown with sensors off to make hand retrieval easier.

Lesson One is a good one because if properly washed, these Mavics can fly again after sinking in 7 m of seawater! How much longer is yet to be seen, but so far about a dozen flights and she still goes. Sssh, shouldn't blab too much about that and chance spoiling my good fortune.

Lesson Two is more important.
My bird was on a Litchi mission, when something went awry shortly after takeoff, and I heard "Mission Aborted" I think I've now figured what caused that, but at the time, flying over an expanse of saltwater, put a shiver up me spine and I pushed the controls to bring her home, only to find they didn't work as expected, so I initiated RTH. Battery levels were about 80%. That brought on the disastrous result and lesson One.

The important lesson came later when I approached Litchi for help and after several emails was told that their program doesn't actually fly the bird, but DJI software does the actually controlling. OK, I approached DJI and good a sympathetic reply pointing out that the manual notes that sensors over calm reflective water can cause it to auto land. They were right, and something all pilot flying over water should keep in mind. But I was troubled still by the "Mission aborted" and other matters so pushed my case and found out the second really important fact. DJI will not warrant a craft flown by Litchi! That's really important. Litchi does not record the flight records that DJI require when assessing a warranty claim. Maybe many of you already know this, but for those that do not, if choosing to fly with Litchi, you do it on your own. Mind, I really like the waypoint control by Litchi, so I still use it.
Hope that helps.

Rise of the Phoenix

 

[Tinmania]

I fly over water, granted only Colorado River so far, but wanted to ask two questions:

1.) How far above the water were you when it auto landed?

2.) Was the Mavic hovering before it auto landed?


Thanks,
Mike

 

[Strobing_NYC]

Never had an issue over water with sensors on, I fly over the Hudson River which is a very large river I have also flown at very low altitude over ponds and lakes, I'm taking less then 3 feet [emoji846] again never an issue.

 

[Flawless]

If I remember correctly, the issue relates to throttling down over water - under certain circumstances with downward vision systems enabled, the Mavic misjudges its height above the waters surface. If it thinks that it is below a foot above the ground and you hold the throttle down, it can try to auto land.

 

[Captain Jack]

I fly over water, granted only Colorado River so far, but wanted to ask two questions:

1.) How far above the water were you when it auto landed?

2.) Was the Mavic hovering before it auto landed?


Thanks,
Mike

Roughly 6 m above the water and it was hovering as I was moving into a retrieval position. It should be noted that the waters of Macquarie Harbour and Gordon River in Tasmania are renown for their reflective nature being darkly stained by passing through buttongrass.
examples Gordon River Lost historical Track Kelly Basin Lost Town

 

[Captain Jack]

If I remember correctly, the issue relates to throttling down over water - under certain circumstances with downward vision systems enabled, the Mavic misjudges its height above the waters surface. If it thinks that it is below a foot above the ground and you hold the throttle down, it can try to auto land.

Throttle had been down to lower aircraft, then released at about 6 m above so that I could get into a suitable hand retrieval position. I've moved on from this after trying both companies to admit liability and renew my craft. But the important point was DJI refused on grounds that I was using Litchi and the flight records they require are not recorded.