Mavic Air Fly Away with Log

[Juice79]

Hey guys hoping for some help on this forum. Experienced my first fly away today after a few months of ownership. Luckily it just scraped the side of a building and I was able to regain site of the craft and control. It looks like it happened about 2:30 seconds into the flight. The log says strong interference after that, but I dont know if that could cause it. Hoping for some help as to the cause. Attached is my flight log. Any help would be appreciated.

 

[Dakarenduro]

I preface this with "I am not an expert"! More experienced users will chime in and help.

But, the log shows you took off with no satellite lock (GPS)?? It wasnt until 1m14.6s that you began showing 6 satellites. Homepoint wasn't recorded until 2m10.2s. Your satellite coverage/count was extremely low the whole flight...

 

[Juice79]

Hopefully others can chime in if that is what would cause a flyaway. If so, lesson learned!!

 

[Meta4]

Experienced my first fly away today after a few months of ownership. Luckily it just scraped the side of a building and I was able to regain site of the craft and control. It looks like it happened about 2:30 seconds into the flight. The log says strong interference after that, but I dont know if that could cause it.

Your drone didn't fly away at all.
The flight data shows GPS health was very low and you only had good GPS for about half of the flight and would have been flying in atti mode without realising it.
WIthout GPS the drone will drift with wind and it won't have any brakes - imagine driving on ice.
You briefly had GPS from 2:20.4 but it dropped out again at 2:31.2.
You were flying quite low and probably under tree cover? that was blocking GPS

 

[Juice79]

I now know that I was flying without GPS. However, the craft took off at full throttle away from me (without any input from me) while it was hovering stable and when I tried to control it by pushing the controls on the opposite direction it was traveling it was not responsive.

 

[Meta4]

I now know that I was flying without GPS. However, the craft took off at full throttle away from me (without any input from me) while it was hovering stable and when I tried to control it by pushing the controls on the opposite direction it was traveling it was not responsive.

There is a short uncommanded acceleration at 2:31.1.
The cause of that isn't immediately clear.
After that it's tricky to tell what accelerations might be a mystery and which are due to the hard moves you made on the joysticks while in atti mode.

The interference at 2:39.7 would have had no effect on the flying.

 

[Dakarenduro]

I dont know exacts, others will, but I seem to remember a minimum of 12 satellites recommended for basic flight. Less than that and you can run into low signal problems (ie. an inability to stay in position).

Were you under tree cover, a thunderstorm, ??

 

[Juice79]

How can you see how many satellites you are connected to before a flight?

 

[Juice79]

There is a short uncommanded acceleration at 2:31.1.
The cause of that isn't immediately clear.
After that it's tricky to tell what accelerations might be a mystery and which are due to the hard moves you made on the joysticks while in atti mode.

The interference at 2:39.7 would have had no effect on the flying.

That uncommanded acceleration is what I'm trying to determine the cause of. That was what caused it to hit the side of a building.

Thanks for all your help guys

Erik

 

[Moose1967]

In my opinion it''s not a fly away - it's called wind drift - a friend of mine bought a $75 drone at Walmart and we went out and I flew mine (MP) and he flew his at the same time - I encouraged him to keep the rear of the drone facing himself - that way left it left and right is right and so on - as soon as he turned it he went crazy with it - it was long into our exercise he realized a HUGE difference - 5 months ago he bought a MPP and never looked back.

One of the main points I told him - never take off until the home point is recorded and you have sufficient satellites for take off.

I know hindsight is 20-20 but get into the routine of doing your pre-flight check list and the last thing on mine is "do I have enough satellites for takeoff" - which is right after "do I have enough clearance from overhanging items". It's not something to rush into.

Happy flying !!!

 

[Dakarenduro]

How can you see how many satellites you are connected to before a flight?

it shows on the DJI Go4 App, across the top line next to the wifi signal icon, there is a sat icon with a number which tells you how many sats you have locked on to.

 

[Dakarenduro]

 

[PoonDog]

At 2.3 seconds into the flight would not be considered a fly away. You just screwed up. Be patient grasshopper , wait for the gods of GPS to embrece you, log your home point then and only then should you break awav from the drudgeries of earth. ? ?

 

[InvisibleName]

How can you see how many satellites you are connected to before a flight?

Asking a basic question like that is somewhat worrying!

 

[DDS]

A bit harsh?...... @Juice79 you have the drone? If so send it in for free inspection free shipping both ways. You only pay of we fix. Also $35 off the repair using mavicpilots

 

[Meta4]

I seem to remember a minimum of 12 satellites recommended for basic flight. Less than that and you can run into low signal problems (ie. an inability to stay in position).

It's not as simple as a single number.
You can have good GPS positioning with less than 12 sats.
The absolute minimum that DJI require is 6 sats, but in most situations you would need more than that.
The way the sats your GPS receiver acquires are spread across the sky is very important.
Low numbers with several clustered fairly close won't be good.

How can you see how many satellites you are connected to before a flight?

As shown above you can see in the app at any time.
You can see the satellite numbers after the flight in the recorded flight data too.
Yours shows that you did not have good GPS at all until 2:10.3 into the flight.
But because the skyview of the GPS antenna was blocked by buildings, trees etc and the drone was very low, it still had a low number of sats locked and GPS was lost and regained a few times during the flight.
Here's a simple view of your flight data that shows the number of sats locked:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

But a more detailed view also shows the GPS Health which accounts for the spread of sats and GPS position reliability.
It shows that your drone only had reliable GPS data for about half of the flight.

 

[Juice79]

It's not as simple as a single number.
You can have good GPS positioning with less than 12 sats.
The absolute minimum that DJI require is 6 sats, but in most situations you would need more than that.
The way the sats your GPS receiver acquires are spread across the sky is very important.
Low numbers with several clustered fairly close won't be good.

As shown above you can see in the app at any time.
You can see the satellite numbers after the flight in the recorded flight data too.
Yours shows that you did not have good GPS at all until 2:10.3 into the flight.
But because the skyview of the GPS antenna was blocked by buildings, trees etc and the drone was very low, it still had a low number of sats locked and GPS was lost and regained a few times during the flight.
Here's a simple view of your flight data that shows the number of sats locked:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

But a more detailed view also shows the GPS Health which accounts for the spread of sats and GPS position reliability.
It shows that your drone only had reliable GPS data for about half of the flight.

Thank you for the informative post. According to what your saying I had a good gps at about 2:10. The uncommanded acceleration was at about 2:30. I completely understand it was my error to take off without a home point or strong gps signal established.

However, I am still looking for a definitive answer if lack of a strong gps signal will/can result in an uncommanded acceleration like I experienced? If yes, the cause of my mishap is clear If no, then I still need to understand what caused the uncommanded acceleration.

Until I am certain that it was the weak gps signal that resulted in this event, I am hesitant to fly the drone again.

I've attached my .dat file in case that helps.

Thanks again for the great info guys!

 

[Meta4]

However, I am still looking for a definitive answer if lack of a strong gps signal will/can result in an uncommanded acceleration like I experienced? If yes, the cause of my mishap is clear If no, then I still need to understand what caused the uncommanded acceleration.

I mentioned in post #6 that I wasn't sure what caused that acceleration.
It appears to be faster than wind drift would cause.
Perhaps @sar104 could dig a little deeper.
He's the .dat file specialist.

 

[sar104]

I mentioned in post #6 that I wasn't sure what caused that acceleration.
It appears to be faster than wind drift would cause.
Perhaps @sar104 could dig a little deeper.
He's the .dat file specialist.

There was a compass error at that time, which may have caused the brief uncontrolled flight:

150.248 : 9714 [L-FDI]NS(0) COMPASS(0): fault on , over_large
150.807 : 9742 [L-FDI][CTRL]: fault on , tilt_ctrl_fail
150.827 : 9743 [L-RC]craft ctrl failed!!!

 

[Juice79]

There was a compass error at that time, which may have caused the brief uncontrolled flight:

150.248 : 9714 [L-FDI]NS(0) COMPASS(0): fault on , over_large
150.807 : 9742 [L-FDI][CTRL]: fault on , tilt_ctrl_fail
150.827 : 9743 [L-RC]craft ctrl failed!!!

Can the compass error have been caused by my error and not having performed the proper pre-flight procedures. Note: I did not have to calibrate the compass prior to take-off on this flight.