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Lost my Mavic 2 Pro in the Gulf of Mexico

big shasta

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Well, the title says it all. The flight logs have been hard to come by because I can't seem to access all the files on my smart controller using a USB cable no matter how many tips I try from this forum. However, I did install the HD Sync app and upload the log to airdata.com. Then I was able to download the CSV file of the log .

Here's how it went down. I had been flying over the water and on the beach the flight before and landed to change the battery. Wife wanted to see an area about a mile offshore so I took off, rotated toward the item and set out over the water. Had good GPS, and was in P-GPS Mode.. I was flying at about 3 ft and climbed to about 8 ft over the water. I had done this earlier to get some video over the water with no issues. Maybe not smart, I know. BUT, when you look at the logs, you can see me climb to about 8 ft but for some reason the sonar altitude shows as low as .3ft and I believe that's when it hit the water. My wife said she thought she saw it touch the water so I went full climb. It shot up to about 35 ft but obviously had ingested water and just dropped out of the sky. It was about 300-350 ft offshore. I tried to swim for it but the water was too murky and I had no snorkel gear. It was lost. I would have been ruined anyway due to the saltwater ingestion.

I don't see how I did anything wrong and have asked DJI to look at the logs. I expect them to go with the "sonar protection not guaranteed over water" or something like that but it seems stable in the log. Why didn't the drone react to the sonar altitude? I don't see "sonar altitude" in the CSV log but it is in the graph of the airdata.com log analysis info.

This site won't let me upload the CSV file or a pic of the airdata log info. How do I put it out there for folks to look at?

Is the airdata.com link all I can do? Here it is.
Thoughts?
 

DanMan32

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You can get the TXT logs by syncing up to DJI, then install Go on an Android device that you can get to files, sync logs down with Go to the Android. IOS is also possible but I hate how you have to use iTunes to get to files.
 

DanMan32

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M2 uses infared for ranging, not ultrasonic. Two cameras for position.

I've found lately barometric based altitude reading to drift off as much as 10ft, though usually you're higher than reading.
If you're going to fly that low over water, turn off VPS.
 

Meta4

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BUT, when you look at the logs, you can see me climb to about 8 ft but for some reason the sonar altitude shows as low as .3ft and I believe that's when it hit the water.
My wife said she thought she saw it touch the water so I went full climb. It shot up to about 35 ft but obviously had ingested water and just dropped out of the sky. It was about 300-350 ft offshore. I tried to swim for it but the water was too murky and I had no snorkel gear. It was lost. I would have been ruined anyway due to the saltwater ingestion.

I don't see how I did anything wrong and have asked DJI to look at the logs. I expect them to go with the "sonar protection not guaranteed over water" or something like that but it seems stable in the log.
Why didn't the drone react to the sonar altitude? I don't see "sonar altitude" in the CSV log but it is in the graph of the airdata.com log analysis info.
Here's what a short version of your flight data looks like: DJI Flight Log Viewer - PhantomHelp.com
You skimmed the water at 0:30 and picked up salt water which is death to electronics.
You climbed and at 0:35.7 the drone briefly and unexpectedly rolls 33 degrees.
The last data record is shortly after at 0:36.2.

Flying into seawater is always a bad thing to do, even just a little.
Your drone does not have "sonar protection" and turning off the VPS sensors wouldn't have made any difference.
 

big shasta

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So what would cause the dip in altitude. I took off from the beach above the water, never went down on the controller why the drift downward into the water? It's not like terrain that could have risen up.

I actually climbed almost 5 feet...but still the actual altitude dropped.
 
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big shasta

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You can get the TXT logs by syncing up to DJI, then install Go on an Android device that you can get to files, sync logs down with Go to the Android. IOS is also possible but I hate how you have to use iTunes to get to files.
Well, I gave it a shot. I was able to get the .txt file but it surely isn't text. It's binary file because it's jibberish when opened as a text file.
 

sar104

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So what would cause the dip in altitude. I took off from the beach above the water, never went down on the controller why the drift downward into the water? It's not like terrain that could have risen up.

I actually climbed almost 5 feet...but still the actual altitude dropped.
If you were hoping that the FC can hold altitude to within a meter while flying at 20 mph over water then you have completely unrealistic expectations.

Climb.png
 
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Meta4

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Well, I gave it a shot. I was able to get the .txt file but it surely isn't text. It's binary file because it's jibberish when opened as a text file.
All you had to do to get the txt file was to click on the "original" link in Airdata.
The .txt file is encoded which is why you can't read it.
 

MAvic_South_Oz

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Hope that is a good lesson learned, most fly a good 10' minimum over water, and even then watch it like a hawk.

Wife wanted to see an area about a mile offshore so I took off
Well, THAT'S convenient !!
You should be able to go straight out and order a new drone body & battery !!
 
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RayOZ

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Looks like it got hit by a wave. Flying that low, probably should be keeping an eye directly on the drone instead of watching the screen.
 

big shasta

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If you were hoping that the FC can hold altitude to within a meter while flying at 20 mph over water then you have completely unrealistic expectations.

View attachment 85951
Well, lets see, I commanded is up 5 feet while in reality it dropped almost 8 feet. Se that's a delta of 13 feet. Yes, I did expect it to hold altitude better than that on a very calm day.

So someone mentioned it "uses infared for ranging, not ultrasonic" Why would they not take a sonar altitude reading into account for safety sake? All of these protections and it ignores a sonar reading of .3 and drifts 13 feet in altitude.

All speculation. Bottom line I was stupid and it cost me. I knew I was taking a risk but I had too much faith in DJI having flown many hours in my Phantom 3 pro. It didn't have any protection but I don't think I ever got altitude loss like this. I've already replaced the drone and have flown a bunch more times. I can't say I'll be skimming the water anymore but I did get some great video of it on that trip.

Here's some raw footage from the night before. I was playing around with settings, speed, height...It didn't like the dusk light and I would get the "Auto braking Center Sticks" a lot. I would have expected that on my next morning flight when it was committing suicide but it had other plans.

I don't need to hear how stupid I am to have flown like this but go ahead if you must. Army Strong, I can take it.
 

Patrick T.

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I fly over the Gulf of Mexico very often I live on the coast of south Texas and one of my favorite spots to shoot videos and some pictures i own a phantom 4pro v2.0 and Mavic 2 Pro I like chasing ships and shrimp boats working on the beach I’ve never had any problems flying over water but I don’t think I would be brave enough to fly that low I’m usually around 30 feet or so and go out 2 or 3 miles
 
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sar104

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Well, lets see, I commanded is up 5 feet while in reality it dropped almost 8 feet. Se that's a delta of 13 feet. Yes, I did expect it to hold altitude better than that on a very calm day.
That's not what the flight data show happened - see the graph above. There is no record of any climb input after auto takeoff.
So someone mentioned it "uses infared for ranging, not ultrasonic" Why would they not take a sonar altitude reading into account for safety sake? All of these protections and it ignores a sonar reading of .3 and drifts 13 feet in altitude.
The height sensors are often not reliable over water. In this case the VPS sensor did detect the ground dropping as you headed off the beach.

Attitude.png
 

DanMan32

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It's not sonar, which uses sound, it's infared, which is light. Water is transparent. In general when not over water, even if the barometric altitude readings drift, it seems to be stable. When VPS readings show low altitude, like approaching 2 ft, it will climb. But with water, it could go right through and read bottom when it's clear with no waves.
 
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Capt KO

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Well, lets see, I commanded is up 5 feet while in reality it dropped almost 8 feet. Se that's a delta of 13 feet. Yes, I did expect it to hold altitude better than that on a very calm day.

So someone mentioned it "uses infared for ranging, not ultrasonic" Why would they not take a sonar altitude reading into account for safety sake? All of these protections and it ignores a sonar reading of .3 and drifts 13 feet in altitude.

All speculation. Bottom line I was stupid and it cost me. I knew I was taking a risk but I had too much faith in DJI having flown many hours in my Phantom 3 pro. It didn't have any protection but I don't think I ever got altitude loss like this. I've already replaced the drone and have flown a bunch more times. I can't say I'll be skimming the water anymore but I did get some great video of it on that trip.

Here's some raw footage from the night before. I was playing around with settings, speed, height...It didn't like the dusk light and I would get the "Auto braking Center Sticks" a lot. I would have expected that on my next morning flight when it was committing suicide but it had other plans.

I don't need to hear how stupid I am to have flown like this but go ahead if you must. Army Strong, I can take it.
It's hard to believe that you didn't lose the drone on this flight. I can see why you were overconfident the next day. Glad you're back in the air. Enjoy
 

RayOZ

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Thanks you've been extremely helpful. There were no waves.
My comment was based on the trend that sar104 provided. The OSD_height didn’t change all that much until 25s, while the OSD_sWaveHeight started the drop and the drone rose on its own before you applied throttle around 30s. So... the only explanation I came up with was a wave rose and touched it. Nothing in the trend showed it lowered on its own. No need for sarcasm.
 

sar104

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My comment was based on the trend that sar104 provided. The OSD_height didn’t change all that much until 25s, while the OSD_sWaveHeight started the drop and the drone rose on its own before you applied throttle around 30s. So... the only explanation I came up with was a wave rose and touched it. Nothing in the trend showed it lowered on its own. No need for sarcasm.
It didn't rise on its own - in fact it didn't rise at all until commanded to at around 23 seconds. The vision-based height increase at 15 seconds, with no associated barometric rise, is just the level of the beach falling off to the water. The aircraft remained in approximately level flight.
 

DanMan32

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Which if OP was watching VPS altitude, would have a false impression of actual height from water surface.
 
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