Help Mavic air lost signal over water

[LM0033]

Hi I need help. flying my drone yesterday 70m away 2.5 m above the water I lost transmission return to home was automatically activated and drone headed towards home point at preset altitude 60m high on descent drone was 10 m away from home point coming down over water, nothing I could do would control the drone as it got closer to the water I pushed Pause button and drone stopped and hovered 2 metres above water, I was completely unable to manoeuvre or control the drone in any way, I had to get into the water and jumped up and whacked the drone towards higher ground before catching it in the air.
Now I have lost all my confidence in flying
What went wrong please help

 

[bigswifty]

Pretty sure the experts will ask for the log files. Here’s how:

Mavic Flight Log Retrieval and Analysis Guide

 

[lannes]

Did you specifically check the home point on the map before taking off ?

 

[LM0033]

Pretty sure the experts will ask for the log files. Here’s how:

Mavic Flight Log Retrieval and Analysis Guide

That you very much for that info that I didn’t know existed
Cheers

Did you specifically check the home point on the map before taking off ?

yes I always check my RTH by flying 10m high then land it using RTH. But I did change the battery and continued to fly before the incident. Do you think that may have something to do with it.

 

[Jimm]

... I did change the battery and continued to fly before the incident. Do you think that may have something to do with it.

My amatuer guess is that when you did the battery switch, it updated the home point to where it thought it was on reboot based on GPS numbers that hadn't settled down - perhaps it was still finding more satellites for more accuracy, but you took off before that could happen and so it had some 'drift' in the home point's location. I don't think this is likely, but technically possible.

There may also have been something big and metallic nearby to throw off the return navigation - buildings, radio towers, power lines, etc., or the GPS got bad numbers from not having enough satellites to get you a high accuracy location fix during the return flight.

Did you hear the 'your home point has been updated, please check it on the map' announcement before launching after the battery swap?

 

[lannes]

That you very much for that info that I didn’t know existed
Cheers

yes I always check my RTH by flying 10m high then land it using RTH. But I did change the battery and continued to fly before the incident. Do you think that may have something to do with it.

Changing the battery would have restarted the drone, the home point would need to be re-acquired by the gps after start up.

 

[boblui]

For Mini and M2P, once RTH is cancelled, full control of the craft by the pilot will be resumed. I guess the Air 1 should be the same in this regard. If you couldn't then something was wrong.

 

[Meta4]

That you very much for that info that I didn’t know existed

Everything so far is just guessing and without any actual data to show what really happened, most is going to be wrong and a waste of time.

If you want to advance past guessing, 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.
The whole process should only take about two minutes.

 

[LM0033]

Everything so far is just guessing and without any actual data to show what really happened, most is going to be wrong and a waste of time.

If you want to advance past guessing, 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.
The whole process should only take about two minutes.

Sorry for the delay not that good with computers but I think I have got the file so I will attach it

Hi I need help. flying my drone yesterday 70m away 2.5 m above the water I lost transmission return to home was automatically activated and drone headed towards home point at preset altitude 60m high on descent drone was 10 m away from home point coming down over water, nothing I could do would control the drone as it got closer to the water I pushed Pause button and drone stopped and hovered 2 metres above water, I was completely unable to manoeuvre or control the drone in any way, I had to get into the water and jumped up and whacked the drone towards higher ground before catching it in the air.
Now I have lost all my confidence in flying
What went wrong please helpView attachment 111160

 

[AMRE2ME2]

Everything so far is just guessing and without any actual data to show what really happened, most is going to be wrong and a waste of time.

If you want to advance past guessing, 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.
The whole process should only take about two minutes.

Thank you! Please everyone, don’t guess! If your guess is wrong, it could very well cause more future problems for the OP and others.
Post the flight logs and the experts will tell you what actually happened.

 

[LM0033]

Sorry again guys I believe that this is the file which contains the info you require.

 

[Meta4]

Sorry again guys I believe that this is the file which contains the info you require.

Good ... because I was just about to say that I thought the other file wasn't the correct one.

 

[Meta4]

Sorry again guys I believe that this is the file which contains the info you require.

Here's what that data looks like.
We have a problem because the flight data only goes until the Mavic is 70 metres out and hovering 4.5 metres above the water.
Signal was lost there and we have no record of what happened after that.
RTH initiated as it's programmed to.

The homepoint recorded at the start of the flight was unchanged when the recorded data ended and it's hard to imagine how it could change on the RTH flight.
The drone should have gone to a point directly above the home point and descended.

Being unable to manoeuvre or control the drone in any way is most likely because you had used the pause button and everything was stopped.

RTH is exceptionally reliable.
I've never seen it perform incorrectly and I'd be surprised if there was a problem with it.
The difficyulty here is that we have no data to show what happened after signal was lost.
Is there any chance that you gave some joystick input as it was descending?

To gain confidence, I'd suggest doing some test flights in a large, open area free of obstacles.
Try flying 30 metres away and initiating RTH and observing the results.
Try it several times and see how it goes.

 

[LM0033]

Here's what that data looks like.
We have a problem because the flight data only goes until the Mavic is 70 metres out and hovering 4.5 metres above the water.
Signal was lost there and we have no record of what happened after that.
RTH initiated as it's programmed to.

The homepoint recorded at the start of the flight was unchanged when the recorded data ended and it's hard to imagine how it could change on the RTH flight.
The drone should have gone to a point directly above the home point and descended.

Being unable to manoeuvre or control the drone in any way is most likely because you had used the pause button and everything was stopped.

RTH is exceptionally reliable.
I've never seen it perform incorrectly and I'd be surprised if there was a problem with it.
The difficyulty here is that we have no data to show what happened after signal was lost.
Is there any chance that you gave some joystick input as it was descending?

To gain confidence, I'd suggest doing some test flights in a large, open area free of obstacles.
Try flying 30 metres away and initiating RTH and observing the results.
Try it several times and see how it goes.

Iam very impressed and thankful for the expertise that you have to determine what would cause this issue. yes it is very likely that i moved the joy stick because i probably panicked when i lost control of the drone and there was a light pole behind me with wires going to it. I still wonder why it hovered 2.5m above the water and there was absolutely nothing I could do with the controller. I think i was very lucky that it was low tide and i was able to jump up and hit the drone in the direction of the higher shore where i could catch it.

 

[Meta4]

yes it is very likely that i moved the joy stick because i probably panicked when i lost control of the drone and there was a light pole behind me with wires going to it.

If you did move the right joystick as the drone was descending, that would explain it being off course (and I can't imagine anything else that would).
The light pole and its cables would have had zero effect on the drone.

The hovering was probably a result of landing protection recognising an unsuitable landing site.

I'd suggest some RTH testing as mentioned above.
You'll see that it always comes back right above the home point and descends properly, which should be good for confidence.

 

[slup]

When looking at BOTH the attached flights they certainly create some question marks ... this due to the timing in them & where the motor start is located on the time line.

When it comes to the .TXT log it start to record when the motors go on ... that usually mark 0sec in the graph, as from one of my own MA1 logs just below where I start up the motors with a CSC command.



But the second attached log here in the thread show this ... the motor start is at 252sec ?!?



Further more the log include 2 HP positions ... One at the same location as the first attached log, but that HP is updated just after take off to a location very close to the beach. This update of the HP just after take off is how it works ... the HP is always verified/updated just after take off.

The 2 flight logs attached in the thread is actually linked (they both points to the same DAT log. FLY061.DAT) as they are actually done during the same power on but the OP took the first flight & started then further away from the river, flew 252sec then landed & the motors shut down ... then took off again without powering down & flew until the connection was lost.

Comparing the different HP positions from both logs & plotting them in GE show this ... the red path with red pins from the first flight, the yellow path with yellow pins from the second take off ... note that the updated HP position for the second attached log (yellow path) aligns to where the first log (red path) ends.



Another view of this here ... have circled the first take off spot to the right & the second at the left.



Actually ... I think you started the motors 3 times during the same power on period. This due to that even the first log you attached don't start up at 0sec instead at 25sec. I think you shortly started up the motors during 25sec before the first log you attached (the red flight path in the pics.) & that even the .TXT log before the first you attached points to the same DAT log as the 2 in this thread.



So the question is ... where did you think you had the HP? Could it have been that the landing/take off spot was very, very close to the water, the HP got updated to be there with some inaccuracy ... but you thought the HP was further up land all the time.

Then when the AC was in RTH to the HP very close to the water (with some inaccuracy) you became surprised that it started to land there.

As stated earlier ... the log doesn't contain the period during the lost video feed so it's hard to say anything about exactly where the AC was when it started to descend. And most likely you had RC connection to the AC when it started to land as it listened to your pause button ... but it's odd that you couldn't gain stick control as pushing pause would stop ongoing automated flight modes ... perhaps you actually lost the connection again after pushing pause.

 

[lannes]

To reduce risk use the "precision landing" function and a landing pad

 

[kidroc]

That battery kinda looks like it was damaged from the fall.. It doesn’t look like it was melted but rather hit there really hard with that white stress crease on it. I don’t know hopefully not a battery problem.

 

[lannes]

That battery kinda looks like it was damaged from the fall.. It doesn’t look like it was melted but rather hit there really hard with that white stress crease on it. I don’t know hopefully not a battery problem.

Not sure what the relevance of your post is to this thread ?

 

[LM0033]

Thanks everyone for your feed back and input I was unaware at the time of just how many wires there are above and around me that showed up in the flight path images that you obtained from my files. do you think that the AC can get interference from them?