DJI Drone Help Forum

Lost drone on water surface


I have just lost my mavic air and would appreciate it if anyone has any tips about figuring out what happened.

I was flying it downward into water surface and next thing I know I my screen went black and that I lost connection. I pressed the Home button, but nothing happened. I have the flight log and it seems that it stopped in the middle of the flight.

Flight record:

I’m really devastated having only had it for not even a year. If anyone can help me understand how I lost it, it would give me a closure.

Many thanks!

The uplink was lost when you flew below the ground where you were standing. As you can see below, that blocked the signal between the remote controller and aircraft. Even though, the remote controller could have still been connected and sending your commands to the aircraft.

When you lost the live video, did you immediately release the sticks and press the home button? Or did you continue to attempt to fly blindly at any point?

Unfortunately this appears to be completely Pilot error. Accordeing to GE your launch point was approx 148ft ASL. As you took the aircraft down below the launch point approx 130 ft, that left you very little altitude to play with above the water. 4 seconds before the end of the log you issued full down throttle and landed it in the water.

What did you see in the log that made you think the aircraft landed in water? The last VPS altitude readings show N/A – which means the aircraft wasn’t close to the surface of the water at the end of the log.

When I lost the live video, I pressed the home button, but I did not get a response. I then tried to fly it back to origin, but that’s when I realized I already lost my drone

@msinger Yes, can you please elaborate @Fly_Dawg?

I am going by the GE terrain profile. As mentioned and shown in the plot above your launch point was ~148ft ASL. ( Which would be 0ft at the launch point). You descended to ~ -30meters ( ~103ft below the launch point ) which would leave you ~ 18ft above the water. Doing the calculations, that last full 4 second full down throttle and forward elevator would have driven the aircraft into the water. That is what I am going by in this instance. VPS can be quite unreliable over water and may or may not respond correctly.

True, but I don’t recall ever see an N/A reading in any instance where the aircraft hit the water (or ground) at some point in the flight log.

While I don’t believe the log reveals the cause of the crash, it seems the aircraft must have either crashed into the water (after the log ended) or into one of those nearby rocks. From what @Steven_G said above, he could have still been flying it after the uplink dropped (which isn’t unusual).

Completely agreed. It is quite unusual, all the N/A means is the fact that the aircraft is above the detection point, as you well know. One would think that there should be at minimum occassional spikes from the VPS at the lower altitude. The difference here being so near the coast and with rock formations that might confuse the sensors with swirling and crashing waters.

Right on. And the lack of spikes either means the downward sensors weren’t working at all (very unlikely) or the aircraft wasn’t close enough to the water.

The downward sensors aren’t always great at returning an accurate distance when flying over reflective surfaces. That doesn’t mean they’ll return no distance though.

Another important thing to note – the aircraft was flying at 16 MPH at the end of the flight log. Had it made impact with the water or a rock, there would have been an abrupt change to the pitch/roll/yaw. None of those values drastically changes near the end of the flight log.

Completely agreed. The downlink was lost just before impact. If you look at the descent rate of 3.2m/s
( 10.5ft/sec ) the aircraft would have hit the water “assuming” that full down throttle was held for 1.5 additional seconds after downlink loss. No way to know that from the lack of data, but could be an accurate assumption.

Thanks for offering an explanation.

I pressed the home button when I first noticed that I lost signal/downlink. Should there have been a chance for the drone to return?

That would mean that the aircraft never recieved the RTH command. After signal loss it takes a few seconds for failsafe RTH to kick in. By that point you had already hit the water. Again, only judging by calculations and the last few seconds of data.,

Wonderful analysis and discussion - and the data and graphics are so helpful.
Is there a tutorial somewhere on how to collect and display an analysis like this?