Lost Mavic 2 in Lake Tahoe

[nordik]

Went flying over the North side of the lake about 1000ft from shore on a clear day (94% battery), signal was lost, RTH failed, and now the Mav is somewhere in the drink.

Crappy part is the flight kept logging data for a couple seconds after disconnect even though I had no visual or control over it anymore, so DJI believes it was pilot error crashing it. Can only hope for someone to find it now.

FAA# FA33ERRXPW

 

[MAvic_South_Oz]

Crappy first post to have to make, but welcome to the forum anyway.

If you have the flight logs, it could pay to post this, as there may be something the good folk here can get from analysis for you.
Pretty simple to do here . . .

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

It will at least show where on / in the lake it might be, and who knows, may yield some clue as to what happened so you and others may know / learn from the incident.

In a very outside chance, with high battery, it may not have crashed ??
There may be a clue that it continued on and landed auto battery, or suffered a blow away, and the analysis can sometimes reveal a place to look.

If you choose to get that Phantom Help link to the flight as above, post it up here in the crash & flyaway section . . .

Crash & Flyaway Assistance

mavicpilots.com

 

[RodPad]

Welcome to the Forum!
Yes that sucks!

Load up your flight log it is free service for a members here.

Rod

 

[easyheimer]

Sorry that happened to you. Following along with hopes something good comes out of this.

 

[Meta4]

Crappy part is the flight kept logging data for a couple seconds after disconnect even though I had no visual or control over it anymore, so DJI believes it was pilot error crashing it.

Did DJI actually say it was user error or was it a case where there was no evidence to show what really happened?

 

[nordik]

Did DJI actually say it was user error or was it a case where there was no evidence to show what really happened?

DJI said it was my error after looking at the data. They said the only reason for the crash was that I landed the drone in the water by using the joysticks to descend and land at the end of the flight path.

Here is the data: DJI Flight Log Viewer - PhantomHelp.com

I figured the fact that the last bit where it hits the water would be damning when dealing with DJI, however I also felt that looking at the change in speed should show an abnormality. Ie: the drone goes from 30mph to 0 within 3 seconds then begins descending and makes a slight turn -- this is bizarre movement that no human would make knowing they're right above the water. You can see prior to that I backed up in order to get a straight line shot of the horizon. Why would I stop and then rapidly descend into the water (while rotating to boot) in 1 second, you know? I lost connection at the rapid speed change point. The DJI app read "RC connected" but there was no visual transmission anymore and RTH didn't respond. I can't prove my side because the data kept logging, though. The only other proof I have is my spotter that watched this flight from shore but again, that's just someone else's word with no proof.

The other aspect of this is I live near 2 lakes and do almost all my practice flights over the water frequently. I'm very familiar with flying over water and haven't had any issues. In fact, earlier that day I did some water flights in Tahoe and they came out smooth.

 

[RodPad]

Looked at your flight very quickly, I thought it was weird that this guy replied about the same time, look at this thread.
How high up in the tree is it?
Location of @BushWacker.

Anyways, If I don't reply tonight on your flight I fell a sleep, but somebody else will with better knowledge will.

Rod

 

[Meta4]

DJI said it was my error after looking at the data. They said the only reason for the crash was that I landed the drone in the water by using the joysticks to descend and land at the end of the flight path.
I figured the fact that the last bit where it hits the water would be damning when dealing with DJI

They kind of have a point because the data shows that your drone was down low over the lake when at 1:31.8 you pulled the left stick down full and held it there until 1:34.2 when it splashed down.
Holding the left stick down caused the final descent.

however I also felt that looking at the change in speed should show an abnormality. Ie: the drone goes from 30mph to 0 within 3 seconds

That's quite normal.
While speeding along at 31 mph your drone was pitched forward at -15°, when you backed off, the pitch reversed to +24°.
Your drone throws in some reverse thrust to brake suddenly.

then begins descending and makes a slight turn -- this is bizarre movement that no human would make knowing they're right above the water.

It might be unusual but if fits the joystick inputs that show in the recorded flight data.
At 1:30.6, almost immediately after backing off on the forward movement, you pushed the left stick fully to the left until the flight data ended.

Why would I stop and then rapidly descend into the water (while rotating to boot) in 1 second, you know?

That's hard to answer but the drone was 1160 feet away and close to the water.
It would have been very difficult to judge how close from that distance.
Flying close to any obstacle is risky and more so when you can't see the drone and any obstacles clearly (and the lake surface is a big obstacle).

The only other proof I have is my spotter that watched this flight from shore but again, that's just someone else's word with no proof.

Your spotter probably can't say anything that contradicts the data.

 

[sar104]

The aircraft disconnected because you flew it into the water:



The aircraft responded correctly to all your stick inputs - throttle - as shown above, and also rudder and elevator:








So at 90 seconds, with the aircraft just a meter or two above the water traveling at 30 mph, you abruptly centered the throttle, applied full left rudder, then full back elevator and full down throttle, and you wonder why it ditched? That was simply horrible piloting.

 

[nordik]

I wouldn't have even bothered contacting DJI or posting flight data if I slammed the stick down into the water -- that's my point here. I lost signal while flying in a straight line. I understand what the data shows and DJI said the same regarding the stick actions, but what I'm saying on my end is that I didn't touch the sticks to descend and the last visual I had of anything was flying at top speed straight with my hand only on the throttle.

To further iterate, I don't have anything to gain by trying to feign responsibility for piloting at this point because DJI had their conclusion, no one is replacing it, and I posted here just in case someone finds it in order to get the SD card. I have no way to prove my end unless something similar happens or has happened with another pilot.

Recently, an FPV pilot from my city also lost signal 400ft off shore in the same area and lost his drone in the water toward the docks of the homes off to the left of my takeoff point after it took a nose dive. Are we all garbage pilots flying off the same beach? Or is there possibly something interfering with transmission in that area? I'm not blaming DJI or trying to smear any names/reputations, I'm just reporting what happened -- and I know the data doesn't support my story, so I can't do much else except say mark it up as a skeptical anecdote and if it happens in the future to anyone else maybe you can reference this thread.

 

[sar104]

I wouldn't have even bothered contacting DJI or posting flight data if I slammed the stick down into the water -- that's my point here. I lost signal while flying in a straight line. I understand what the data shows and DJI said the same regarding the stick actions, but what I'm saying on my end is that I didn't touch the sticks to descend and the last visual I had of anything was flying at top speed straight with my hand only on the throttle.

To further iterate, I don't have anything to gain by trying to feign responsibility for piloting at this point because DJI had their conclusion, no one is replacing it, and I posted here just in case someone finds it in order to get the SD card. I have no way to prove my end unless something similar happens or has happened with another pilot.

Recently, an FPV pilot from my city also lost signal 400ft off shore in the same area and lost his drone in the water toward the docks of the homes off to the left of my takeoff point after it took a nose dive. Are we all garbage pilots flying off the same beach? Or is there possibly something interfering with transmission in that area? I'm not blaming DJI or trying to smear any names/reputations, I'm just reporting what happened -- and I know the data doesn't support my story, so I can't do much else except say mark it up as a skeptical anecdote and if it happens in the future to anyone else maybe you can reference this thread.

If that is your recollection then it is simply incorrect - by no means the first time that it has happened.

 

[Meta4]

I wouldn't have even bothered contacting DJI or posting flight data if I slammed the stick down into the water.
-- that's my point here. I lost signal while flying in a straight line. I understand what the data shows and DJI said the same regarding the stick actions, but what I'm saying on my end is that I didn't touch the sticks to descend and the last visual I had of anything was flying at top speed straight with my hand only on the throttle.

This is a very, very different story from what the data is telling.
Are you suggesting the recorded data describes a completely fictional incident and is just wrong?

Recently, an FPV pilot from my city also lost signal 400ft off shore in the same area and lost his drone in the water toward the docks of the homes off to the left of my takeoff point after it took a nose dive. Are we all garbage pilots flying off the same beach? Or is there possibly something interfering with transmission in that area?

To suggest any link between a fall-from-400ft incident and driving into the lake from just a few feet up is a big stretch.
Interference, at worst would only swamp your control signal and trigger RTH.
Interference doesn't make your drone fly off somewhere else.
But if it did, it wouldn't leave joystick inputs to show in the flight data.

 

[nordik]

This is a very, very different story from what the data is telling.
Are you suggesting the recorded data describes a completely fictional incident and is just wrong?

No, I'm suggesting or wondering if there is the possibility of signal interference (or previously wondering if organic malfunction is possible) to send a false signal (ie: rudder or throttle actions) in the midst of a transmission issues. I don't know enough about radio transmission to know if that is something that is realistic in 2020 or more of a movie-esque imagination, but I do not have any other explanation within my scope of knowledge. What I experienced more so mimics the "Skyfence" drone defense videos you see on Youtube where signal is lost and the drone lands right where signal is lost after RTH fails, but like I said, I don't have an explanation beyond what I'm attempting to convey.

Again, nothing is gained here on my end by disputing data on paper when I know I'm risking sounding completely discreditable and like a moron. I wouldn't have risked posting the data knowing what it says if I didn't have a different take on what occurred than what the data suggests. I'm also aware of what sar104 is saying when referencing the phenomenon of witnesses having inaccurate recollection of stressful or traumatic incidents. I believe the data when it says the drone descended into the water due to a remote action, but I'm saying I didn't have control at that point and I do not know how to technically explain what occurred.

The exact sequence of events was as follows:

1) Flying in a straight line toward the horizon
2) Signal lost, I figured it would RTH
3) Ask spotter if he has eyes on it, he says no
4) Wait a minute for RTH, nothing occurs. Hit RTH button on remote and wait...still nothing after a few minutes

 

[Meta4]

The exact sequence of events was as follows:
1) Flying in a straight line toward the horizon
2) Signal lost, I figured it would RTH
3) Ask spotter if he has eyes on it, he says no
4) Wait a minute for RTH, nothing occurs. Hit RTH button on remote and wait...still nothing after a few minutes

2. Signal was lost when the drone went into the drink
3. Did the spotter have sight of the drone?
Does he say it kept flying one or did he see it dive in?
4. RTH isn't going to happen when the drone has gone submarine.

It's very hard to argue against recorded joystick inputs.
No sci-fi interference is going to show as joystick input.

 

[nordik]

2. Signal was lost when the drone went into the drink
3. Did the spotter have sight of the drone?
Does he say it kept flying one or did he see it dive in?
4. RTH isn't going to happen when the drone has gone submarine.

In the area the drone went down there was 3+ bouys floating. He said he lost sight of the drone around those buoys and later believed it went down there (he never saw the actual striking of the water, no one did). I was headed toward that buoy area when flying so he didn't know if it disappeared behind those buoys.

At the time of the incident we didn't know if the drone was even in the water or not. He was looking toward the sky/horizon to see if it was returning to home or not. He was about 100 yards ahead of me watching. I ran over and looked for the same. Obviously, when nothing was coming back we figured it went down in the water at some point. When I got home to a computer I ran the flight data to see what happened because the last visual I had was the signal cutting out like a TV would as it was flying toward the horizon.

It's very hard to argue against recorded joystick inputs.
No sci-fi interference is going to show as joystick input.

Understood.

 

[xspwhite]

In the area the drone went down there was 3+ bouys floating. He said he lost sight of the drone around those buoys and later believed it went down there (he never saw the actual striking of the water, no one did). I was headed toward that buoy area when flying so he didn't know if it disappeared behind those buoys.

At the time of the incident we didn't know if the drone was even in the water or not. He was looking toward the sky/horizon to see if it was returning to home or not. He was about 100 yards ahead of me watching. I ran over and looked for the same. Obviously, when nothing was coming back we figured it went down in the water at some point. When I got home to a computer I ran the flight data to see what happened because the last visual I had was the signal cutting out like a TV would as it was flying toward the horizon.



Understood.

Flying just a few feet above the water is a bad idea. Flying just a few feet above the water when you cant even see the drone is a terrible idea.

 

[Flycaster]

I wonder if it was just the app disconnecting, and not the AC/Controller??

 

[sar104]

I wonder if it was just the app disconnecting, and not the AC/Controller??

Then it wouldn't have continued logging, so that's clearly not what happened. The disconnect was due to the antennas going underwater.

 

[BushWacker]

Looked at your flight very quickly, I thought it was weird that this guy replied about the same time, look at this thread.
How high up in the tree is it?
Location of @BushWacker.

Anyways, If I don't reply tonight on your flight I fell a sleep, but somebody else will with better knowledge will.

Rod

What is weird about this? I'm the one that lost my Mini in the tree. I never did find it, I got a new drone and went up there and looked for it with the new drone but the old one is nowhere to be found. I'm sure Lake Tahoe has claimed many a drone, rumor is there are people down there with concrete sneakers too... Sorry to hear about your loss, you get attached to them, like losing a pet snake or something.

 

[GadgetGuy]

What is weird about this? I'm the one that lost my Mini in the tree. I never did find it, I got a new drone and went up there and looked for it with the new drone but the old one is nowhere to be found. I'm sure Lake Tahoe has claimed many a drone, rumor is there are people down there with concrete sneakers too... Sorry to hear about your loss, you get attached to them, like losing a pet snake or something.

At 1645 feet deep, it is challenging to recover anything, whether animal, mineral, or vegetable!