Almost Lost My M3 In The Ocean !

[Tim3459575]

Hi

I fly my M3 drone from a boat, and use a home made catch handle which is a huge improvement for hand catching. However, although positioned between the two bottom sensors, I do get random messages that a vision sensor is blocked (see attached photos). These occasional warnings seemed to have no effect on flight performance. However, I recently had a close call when after a normal flight the drone, when 20’ up and 20’ away from the boat started descending on it’s own with a repeating audible warning: “landing, landing …”. it was not responding to the up stick, but luckily it would respond to go sideways, and as it came down, I just barely was able to get it to the side of the boat and catch it before it went into the ocean.
In view of this extremely close call, I’m wondering if anyone has thoughts on why this happened and how I can avoid this on future flights ? Could a blocked sensor cause this ?

Additionally, since then, I have received warnings about a vision sensor not working even when the stick was not attached.

I can post a flight log if that helps but would need a bit of guidance on how to do that. Any feedback on this would be greatly appreciated.

Thank you, Tim

 

[RUFFSTUFF]

Horrible.

 

[GFields]

It is very possible that the catching device caused some problems with the sensors.

I would post the flight logs and let some of the experts on the forum see if they can tell you more.

I do know that DJI does not recommend hand catching. "DJI does not recommend hand catching your DJI drone or any DJI drone for safety purposes. Please do not stop the drone by hand, it could be dangerous and please land the said drone and stop the motors by sticks, or use the auto landing function if possible. Thank you for your kind understanding and have a nice day" DJI Stephen, Super Moderator

I nearly lost a thumb trying to catch a crashing Inspire 2 (out of reflex).

 

[Phantomrain.org]

You might consider getting the Rescue Jacket for the Mavic 3 , as its streamline , easy hand catching and fully tested and perfect for being on the boat.

Rescue Jacket in Action :
M3 on the water.
M3 in sport mode

It is easy for that stick you may to slide over the Landing Sensor, which could be a possible cause for that behavior.

Phantomrain.org
Gear to fly in the Rain > Land on the water.

 

[GFields]

You might consider getting the Rescue Jacket for the Mavic 3 , as its streamline , easy hand catching and fully tested and perfect for being on the boat.

Rescue Jacket in Action :
M3 on the water.
M3 in sport mode

It is easy for that stick you may to slide over the Landing Sensor, which could be a possible cause for that behavior.

Phantomrain.org
Gear to fly in the Rain > Land on the water.
View attachment 150697

I agree. Anyone that is going to be flying from a boat or over water would be ahead of the game to have a Rescue Jacket. I bought one for my Phantom 4 Pro and Air 2s

 

[Meta4]

Could a blocked sensor cause this ?

Additionally, since then, I have received warnings about a vision sensor not working even when the stick was not attached.

I can post a flight log if that helps but would need a bit of guidance on how to do that. Any feedback on this would be greatly appreciated.

The flight data would be very useful to see what the sensor is doing.
Post data for the problem flight and also for one where you are getting warnings without the handle attached.

Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
Or .. just post the txt file here.

 

[Tim3459575]

thanks for the feedback. how does the rescue jacket affect flight performance and flight time ?

The flight data would be very useful to see what the sensor is doing.
Post data for the problem flight and also for one where you are getting warnings without the handle attached.

Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
Or .. just post the txt file here.

 

[Tim3459575]

thanks for the feedback Meta4. I found the folder “flightrecords” for the DJI Fly app on iTunes. However, I’ve been unable to open the folder and select the file for upload. When I click or double click the folder nothing happened. Do you have any suggestions on how to get the file under these circumstances ? thanks for your help !

 

[Meta4]

thanks for the feedback Meta4. I found the folder “flightrecords” for the DJI Fly app on iTunes. However, I’ve been unable to open the folder and select the file for upload. When I click or double click the folder nothing happened. Do you have any suggestions on how to get the file under these circumstances ? thanks for your help !

Sorry, I don't use Apple devices so can't help with that.

 

[Yorkshire_Pud]

You will not be able to open the folder, or at least with iTunes on a windows PC that is what I have found. I had to copy the entire flightrecords folder to the pc........

 

[Tim3459575]

The flight data would be very useful to see what the sensor is doing.
Post data for the problem flight and also for one where you are getting warnings without the handle attached.

Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
Or .. just post the txt file here.

 

[Tim3459575]

Here's the flight log. Hopefully this sheds some light on what transpired. thanks for your help.

 

[Meta4]

Here's the flight log. Hopefully this sheds some light on what transpired. thanks for your help.

Here's what that flight data looks like:

DJI Flight Log Viewer - PhantomHelp.com

Compare the two columns labelled IMU altitude (the height you see in the app) and VPS altitude (what the downward facing sensors think the height above whatever is below the drone.

VPS has a limited range, so it shows as N/A when the drone is higher than the sensors range.
The sensor is giving false height dataafter launching - IMU = 40 ft, VPS = 5.9 ft
And when descending 27 ft = 0.7 ft.
This is why the drone slowed its descent - the VPS indicated it was just about to land.

There are a couple of messages that say Low environmental visibility.
I haven't seen that before.
Was there a lot of mist or salt spray in the air?
If not, I'd suggest recalibrating the VPS sensors might be needed.

 

[Tim3459575]

thank you Meta4 for these comments. There was in fact a thick fog so that would explain the low environmental visibility. As regards the VPS, if it reads .7’ would that trigger an auto landing sequence ? If so, is there a way to override that ? Also, the catch handle partially obscure the sensors. perhaps if I move it to totally obscure one sensor and give more visibility to the other that would give more accurate readings ?

thanks again for your input - it’s greatly appreciated

 

[Meta4]

thank you Meta4 for these comments. There was in fact a thick fog so that would explain the low environmental visibility. As regards the VPS, if it reads .7’ would that trigger an auto landing sequence ?

When the VPS is indicating the ground is just below the drone that triggers landing protection.
Pulling the left stick down with the VPS showing less than 1 metre forces landing.

If so, is there a way to override that ?

Unfortunately DJI don't seem to think it's important and haven't given the ability to disable VPS in the DJI Fly app.

Also, the catch handle partially obscure the sensors. perhaps if I move it to totally obscure one sensor and give more visibility to the other that would give more accurate readings ?

You could do some testing on land to see if that helps.

 

[Garatshay]

Hi

I fly my M3 drone from a boat, and use a home made catch handle which is a huge improvement for hand catching. However, although positioned between the two bottom sensors, I do get random messages that a vision sensor is blocked (see attached photos). These occasional warnings seemed to have no effect on flight performance. However, I recently had a close call when after a normal flight the drone, when 20’ up and 20’ away from the boat started descending on it’s own with a repeating audible warning: “landing, landing …”. it was not responding to the up stick, but luckily it would respond to go sideways, and as it came down, I just barely was able to get it to the side of the boat and catch it before it went into the ocean.
In view of this extremely close call, I’m wondering if anyone has thoughts on why this happened and how I can avoid this on future flights ? Could a blocked sensor cause this ?

Additionally, since then, I have received warnings about a vision sensor not working even when the stick was not attached.

I can post a flight log if that helps but would need a bit of guidance on how to do that. Any feedback on this would be greatly appreciated.

Thank you, Tim

I had a couple of frights recently with a Mavic 3 operated from a boat. In my case, the issue was the RTH triggering automatically because the drone decided to land early because it believed that it was too far from the original Home Point and only had sufficient battery life to land safely. I made the decision that day to chase boats only from a fixed shore position in future. I know there's a 'change the Homepoint' option, but that seems to be courting disaster during a flight.

 

[Meta4]

I know there's a 'change the Homepoint' option, but that seems to be courting disaster during a flight.

It's a simple matter to reset the homepoint to the drone's current location a few times during the flight to avoid ending up with the homepoint a few miles back and the drone wanting to zip away because it has only just enough battery to get back there.

 

[Garatshay]

It's a simple matter to reset the homepoint to the drone's current location a few times during the flight to avoid ending up with the homepoint a few miles back and the drone wanting to zip away because it has only just enough battery to get back there.

I don’t disagree, but it’s a complication I prefer to avoid in future.

 

[Tim3459575]

Here's what that flight data looks like:

DJI Flight Log Viewer - PhantomHelp.com

Compare the two columns labelled IMU altitude (the height you see in the app) and VPS altitude (what the downward facing sensors think the height above whatever is below the drone.

VPS has a limited range, so it shows as N/A when the drone is higher than the sensors range.
The sensor is giving false height dataafter launching - IMU = 40 ft, VPS = 5.9 ft
And when descending 27 ft = 0.7 ft.
This is why the drone slowed its descent - the VPS indicated it was just about to land.

There are a couple of messages that say Low environmental visibility.
I haven't seen that before.
Was there a lot of mist or salt spray in the air?
If not, I'd suggest recalibrating the VPS sensors might be needed.

Hi Again Meta4,

Now back from my trip and re-reviewing this info you provided. I see from the log the discrepancy between IMU and VPS altitude starting at 3 min, 34 sec. However, it continues to fly in tripod mode until 4m, 8s when it momentarily switches to “P-GPS”, and then “forced landing”. Presumably “forced landing” means it’s landing regardless of pilot input ? Do you have any theory on what triggered the forced landing given that it was already flying with an altitude discrepancy for 30 seconds in tripod mode ?

Any further input you have on this would be much appreciated.

thank you,

 

[Meta4]

Do you have any theory on what triggered the forced landing given that it was already flying with an altitude discrepancy for 30 seconds in tripod mode ?

Flying with the VPS indicating a very low height doesn't force a landing.
Holding the left stick down for some time while the VPS indicates a very low height is what triggers a forced landing.