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MAVIC AIR - REFUSES TO RETURN OVER WATER

SPIGGOTT

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Hi,

Just had a very strange incident and very costly accident with my Mavic Air 2.

Just travelled to Jamaica to record footage of a project i am doing at the local reservoir.

Setup my Mavic Air 2 at side of the reservoir and launched and lifted up to about 15ft. I usually then try out all movements to check for problems.
So far nothing wrong. I then flew out about 40 meters to try and track a USV that we had in the water. On the flight to it the MA2 dropped and then lifted in altitude on its own. It was not a lot but being over water and being a bit cautious i decided to return back. I turned round and about 10 meters from the edge of the RES the MA2 stopped as if collision avoidance halted it. Then the app bellowed out MAX FLIGHT DISTANCE REACHED. Seeing as i was returning to home point i could not see how this was possible.

I tried every direction to move from being over water with the same result when the drone got 10-15 meters from shore. Almost like an invisible force field around the reservoir.

This carried on until the low battery warning at which point it tried to return to HOME itself. Instead of moving it proceeded to land exactly where it was over the water. So i quickly cancelled the landing and tried to move again with no luck. eventually i had to sit there and watch it hover over the water until the battery ran out and it crashed.

Anyone know what the( Mod Removed Language)happened here.....


IMG_9300.PNG

thanks
 
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Agustine

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Follow the instructions on here to get your log files. Post it here and someone might be able to help you out.
 

SPIGGOTT

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Hi,

Thanks for the help. Just done that and it shows so very weird things going on.

0m 19.8sP-GPS7satellites16.1ftN/A1.1mph0ftGPS signal weak. Hovering unstable. Fly with caution (Code 30002).
0m 19.9sATTI7satellites16.7ftN/A1.1mph0ftGPS signal weak. Switched to Attitude mode. Aircraft unable to hover. Fly with caution.
0m 20sATTI7satellites17.4ftN/A0.9mph0ftCompass or GPS signal weak. Changed to Attitude mode.
0m 20.1sATTI7satellites18.0ftN/A0.9mph0ftGPS signal weak. Switched to Attitude mode. Aircraft unable to hover. Fly with caution.; Aircraft in Attitude mode. Unable to hover. Fly with caution (Code 30004).; Compass or GPS signal weak. Changed to Attitude mode.
0m 20.3sATTI9satellites19.4ftN/A0.7mph0ft
0m 20.7sP-GPS9satellites20.3ftN/A3.4mph0ftGPS signal weak. Hovering unstable. Fly with caution (Code 30002).

This is what i experienced and then tried to return.

I only get a few messages after that but very strange. It appears that i lost internet connection at 57.2s. The message then reads "DFlight altitude restricted. Log in or go to real-name authentication." at 59.1s into flight download link was restored and it did this "Homepoint updated. RTH altitude adjusted to 75m."

From the point i could not return back to the shore. The picture below shows the flight path trying to get back. it seems to have locked me to a radius circle 40m out into the reservoir only letting me move 30m in any direction.
 

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CalOldBlue

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A little late now, but I wonder what would have happened if you'd gone into the app and increased the maximum flight distance? Seems like it got set to a very small value and home got reset to be over the reservoir.
 

slup

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...Anyone know what the( Mod Removed Language)happened here...
As you haven't shared the PhantomHelp link to your flight log so we can check off what happened we can only speculate in this stage ...

But suspect that this is due to what is written on page 2 in the full downloadable manual --> https://dl.djicdn.com/downloads/Mavic_Air_2/Mavic_Air_2_User_Manual_v1.6_enIII.pdf

1629444572444.png

If first looking at the pic you showed over the flight from PhantomHelp ... all flight paths is out over the water, no path goes to a possible HP over solid ground.

1629444672603.png
This means that you most probably flew out over the water without a GPS lock & by that no recorded HP. This is somewhat confirmed by another pic you shared from PhantomHelp ... ATTI mode very early in the flight.

1629444825816.png
So by flying out without a GPS lock prevented the distance & height restrictions I showed you from page 2 in the manual above as it wasn't any HP to relate the distance too.

Then out over the reservoir you got a GPS lock ... & a HP was recorded then & there. This made the distance & height restrictions active as it now existed a HP to relate too... and the green flight path start to appear in PhantomHelp.

This + that you wasn't logged in to your DJI account in the app is somewhat confirmed with what you write here ...

1629445134912.png

So it appears that this was a plain pilot error coming from not waiting for a GPS lock & a recorded HP before take off + not being logged in to the DJI account in the app.

And as said ... with no log shared this is just a plausible reason for this incident.

And just for the record ... no restricted flight zone exists in the DJI Fy Safe material in the drone (which is the only thing that can physically prevent the drone to fly) over the Mona Reservoir ... as seen here.

1629446194441.png
 
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PhiliusFoggg

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Impressive analysis Slup, or should we call you Sherlock?

Just to see if I understand what you are suggesting correctly.
You are thinking that Spiggot took off and flew without being logged into the app?
Since he? took off with insufficient GPS satellites no restrictions, relating to not being logged into the app, applied, .....BUT......once sufficient GPS satellites were obtained a homepoint was set and that home point became the anchor point for the above restrictions. Since that home point was well out from the shoreline the drone was, because of those restrictions, unable to reach land.
Is my understanding correct?

If so it leads to the question, what might have happened if Spiggot had reset the homepoint to the controller's position? ( If that is still possible with the Air 2.)
The reason for my question is....I often take off with out sufficient satellites as my at home take off point has a rather tree obstructed view of the sky though I am normally logged into the app, however it would be a useful thing to know....just in case.

To Spiggot, I know hindsight is a wonderful thing but could you have swum safely etc. to underneath the drone and caught it as it descended etc. etc.?
 
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Meta4

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Is my understanding correct?
Yes
If so it leads to the question, what might have happened if Spiggot had reset the homepoint to the controller's position? ( If that is still possible with the Air 2.)
Resetting the home point to the aircraft's position would have solved the problem, with additional resets if the distance wasn't enough.
Resetting the homepoint is possible with all DJI drones.
The reason for my question is....I often take off with out sufficient satellites as my at home take off point has a rather tree obstructed view of the sky
All you need to do is hover above your window to get a homepoint up there.
 

SPIGGOTT

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1. I am in a foreign country doing this so no phone service or internet. Could not log into my account.
2. GPS signal was locked at startup and homepoint set.
3. It would not let me reset a new homepoint.
4. When the battery ran low, it returned to the homepoint it set which was then 20 meters from where i jumped in and tried to swim to it.
 

PhiliusFoggg

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1. I am in a foreign country doing this so no phone service or internet. Could not log into my account.
That is something for everyone to remember, I bet most people leave themselves logged in and forget that should the need arise an internet connection is needed to log in. I just tried it with wifi off, oooooH
4. When the battery ran low, it returned to the homepoint it set which was then 20 meters from where i jumped in and tried to swim to it.

Ahhh that was a pity.
 
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BossBob

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The
1. I am in a foreign country doing this so no phone service or internet. Could not log into my account.
2. GPS signal was locked at startup and homepoint set.
3. It would not let me reset a new homepoint.
4. When the battery ran low, it returned to the homepoint it set which was then 20 meters from where i jumped in and tried to swim to it.
Yet in your original post you mentioned that you’d lost an Internet connection at 57 seconds.
The information you gave only ever mentions weak gps signal, attitude mode and 7 to 9 satellites. I’ve never had a homepoint set with less than 10 satellites.
Follow the instructions and post access to the log then the experts will be able to tell you what the drone was doing, not what you think it was doing.
 

cgmaxed

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A little late now, but I wonder what would have happened if you'd gone into the app and increased the maximum flight distance? Seems like it got set to a very small value and home got reset to be over the reservoir.
I agree, I think he may have left his launch home point without a GPS lock, but acquired a GPS lock over the reservoir at which time the drone created a home point. The home point had to be over the water for that message to pop up. Another reason not to put a distance limit on your drone. Did you, the OP, have a distance limit set?
 

slup

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1. I am in a foreign country doing this so no phone service or internet. Could not log into my account.
2. GPS signal was locked at startup and homepoint set.
...

1. An internet connection isn't necessary if you was logged in previous losing the internet connection ... it only becomes a problem if you're logged out & don't have connection when you shall log in. If in a situation, logged out & lack connection it's crucial to be aware of the limitations ... as you became aware of in the worst possible location.

2. According to the limited info you have shown us so far your drone was in ATTI mode at 19,9sec (no GPS lock ... or at least not enough satellites locked to get horizontal hold) no HP will be recorded in that mode... furthermore the PhantomHelp pic. you showed don't have anything logged over ground, all paths & markers is over the water. And on top of this, a new HP isn't usually re-recorded if losing GPS lock momentarily during a flight... if it was recorded at take off. All this indicate that you hadn't any HP recorded when you took off.

The log will show all facts around this ... share the link PhantomHelp provided when you uploaded the log there. If you missed to note the link, just upload the log there again.
 
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spsphotos

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This is why one needs to invest in a PhantomRain life preserver and rain jacket. :). Suck losing a drone to the water Gods. :(
 

Capt KO

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Wouldn’t Atti mode have solved the problem? GPS lock was holding it in place.
 

slup

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uploaded log.
The log pretty much confirms my initial theory ...

The HP is only recorded once the flight controller get enough confidence in the positional information, the numbers of satellites locked doesn't matter ... on a 1-5 scale that happens when the GPS level reaches 4 out of 5.

Here both number of locked in satellites & GPS level is depicted in a chart ... the HP gets recorded for the first time at 25,6sec into the flight with 9 satellites locked.

(Click on the chart to make it larger)
1629467784178.png

All above & more is also shown in the TXT log message stream... the HP became recorded for the first time at 25,6sec into the flight. It also already at 0,6sec confirms that you weren't logged into your DJI account in the app.

(Click on the pic to make it larger)
1629466723920.png
When the HP got recorded your MA2 was out over the water, approx 22ft above the surface ... the red star is your AC location when the HP gets recorded (the green bar shows in which direction it points), the green star is where the HP got recorded.

1629466748972.png
 
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Meta4

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2. GPS signal was locked at startup and homepoint set.
Your drone falsely declared GPS-Mode, despite having no GPS location data until 21 seconds and was not able to record a home point until 25.6 secs.

This is something that I've seen a few times lately.
I'm not sure why this happens.

You can confirm that the drone really has GPS, by waiting for the home point to be recorded and you can also check the distance displayed.
With no homepoint, there will be no distance (because the distance is the distance from the home point).
 
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