Recovered from a flyaway

[virtualphotographers]

I'll begin by saying I've flown all sorts of DJI multi rotors... Flamewheels, phantoms, Inspires, an S800EVO and now the Mavic. Till a week or so ago, I have never experienced an actual flyaway. But now, I can say I've seen it happen and fortunately, I was able to regain control. Here's what happened:

I was flying taking photos and video of my brothers place. All was going fine and after a half dozen flights I was up getting a last shot. It was windy but not so much the aircraft was overwhelmed. Sent it up above tree level, was taking video and everything was stable, then, the Mavic rapidly took off in a straight line backward and sticks didn't respond.

My first instinct was to hit RTH. Got a notification the RTH was not able to be initiated.
Tried the sticks again, no go.
Then I flipped the SPORT MODE switch and tried again. Got stick control and stopped the runaway. Was able to fly back in atti mode and land.

Haven't flown since but soon as weather cooperates, I'll get the bird up again but I have to say, that was a sobering experience and I'm glad I was flying above obstructions and at close range. I imagine things would have been different if I was out flying long range. I'll post video shortly

 

[virtualphotographers]

@virtualphotographers .... you going to finish that thought? Upload .txt to Airdata.com too please.

Did... You caught the post mid edit. It's all there

 

[AlanTheBeast]

Would like it if you post the TXT file from the controller on Airdata.com and/or Phantomhelp

 

[virtualphotographers]

You bet. I assume you want more than the logs in the app. How does one pull logs from the controller or aircraft? Haven't done this on a mavic before and the dji assistant does not connect to either

 

[geigy]

Sounds exactly like what happened to me at one point - lost GPS, ATTI mode, drifting with a lively wind, and no response to the sticks for a good 10 or 20 seconds. I had a transponder (Loc8tor) button stuck on the body near the GPS antenna.

Relocated the Loc8tor to one of the arms and have not seen the problem since, but loss of GPS does not explain why the bird would not respond to the sticks.

 

[rydfree]

Don't really know if it can be called a flyaway if you landed it .

 

[BorisTheSpider]

Thanks for posting - I look forward to seeing your DAT file from this flight.

If DJI assistant won't connect then it's probably your USB cable or that the drivers didn't install correctly on the PC you're using to try to access the DAT - if you're able, please don't fly the mavic again until the file is pulled so it can't be overwritten.

 

[apu]

I am starting to get used to the idea that every once in a while my mavic wants to be free to do its own thing
I have had 2 fly aways that I was able to recover from, The first when I was flying it using the controller without my phone attached and it just decided it was going to fly due north at full speed by itself, it responded to the sticks but fought me for around 10-15 seconds. No it wasn't wind. The second happened when my connected Samsung S6 running DJI app got a telephone call while I was flying. Again it made a bee line strait north, fortunately the sticks were still responsive and I was able to give it altitude before it hit some trees and it bought me a little time to fight it back, after a few seconds it stopped resisting.

 

[geigy]

Don't really know if it can be called a flyaway if you landed it .

Maybe we should call them "try aways".

 

[SkunkWerx's]

If I may ask you op's what was your flying environment like ex. your Yard, a Park , the Beach ???

 

[geigy]

Been thinking about this. I think It's possible to explain this behavior with a bad GPS lock.

1. The Mavic gets a bad GPS lock at take-off time - say off by 50 meters.
2. A subsequent accurate GPS lock will make the bird think it was knocked out of position by 50 meters.
3. The Mavic will do everything in its power to move to the location of the bad GPS lock. (this explains the sticks going dead)
4. Once the Mavic thinks it is in position, it responds normally to the controls.

If there are ongoing GPS issues such as nearby tall buildings, a sticker over the GPS antenna, or other issue this scenario could repeat itself indefinitely.

 

[JasonStahl]

Don't really know if it can be called a flyaway if you landed it .

You must be a liberal.

 

[SkunkWerx's]

Been thinking about this. I think It's possible to explain this behavior with a bad GPS lock.

1. The Mavic gets a bad GPS lock at take-off time - say off by 50 meters.
2. A subsequent accurate GPS lock will make the bird think it was knocked out of position by 50 meters.
3. The Mavic will do everything in its power to move to the location of the bad GPS lock. (this explains the sticks going dead)
4. Once the Mavic thinks it is in position, it responds normally to the controls.

If there are ongoing GPS issues such as nearby tall buildings, a sticker over the GPS antenna, or other issue this scenario could repeat itself indefinitely.

When your in P-Mode you are controlling the Mavic , the GPS I believe is being used for the GO4 app telemetry
I asked about the flying environment because there are interference's that do not show up as a warning until
the Mavic goes down, lost or just too late an crash
The last story I was following the pilot took off from a metal bench and it just went where it wanted to go till it crashed
The best part about it was the pilot got his Mavic replaced for free and DJI did not tell him why it happen he keeps trying to find out but no one is getting back to him

 

[SkunkWerx's]

You must be a liberal.

I like the sound of it -- TRY AWAY lollllll

 

[geigy]

When your in P-Mode you are controlling the Mavic , the GPS I believe is being used for the GO4 app telemetry
I asked about the flying environment because there are interference's that do not show up as a warning until
the Mavic goes down, lost or just too late an crash
The last story I was following the pilot took off from a metal bench and it just went where it wanted to go till it crashed
The best part about it was the pilot got his Mavic replaced for free and DJI did not tell him why it happen he keeps trying to find out but no one is getting back to him

But the GPS location is also used in P mode to maintain a hover or straight line. If there is a position error, it seems to me, the Mavic will try to move to the "correct" location, and integrate that with the input from the sticks.

I phoned DJI and they immediately suggested that I send the Mavic in to them for servicing. I didn't do this - instead I moved a Loc8tor button away from the GPS and have not seen the behavior since.

Be that as it may, there appear to be a number of these small fly-aways. It's an unforgettable experience when it happens.

 

[SkunkWerx's]

But the GPS location is also used in P mode to maintain a hover or straight line. If there is a position error, it seems to me, the Mavic will try to move to the "correct" location, and integrate that with the input from the sticks.

I phoned DJI and they immediately suggested that I send the Mavic in to them for servicing. I didn't do this - instead I moved a Loc8tor button away from the GPS and have not seen the behavior since.

Be that as it may, there appear to be a number of these small fly-aways. It's an unforgettable experience when it happens.

I believe it also works in the way you say -- "When in Hover " But then when it gets an input signal from the pilot to go in a certain direction The GPS no longer is in play it's only being used now for the App telemetry
It's a slippery slope with the sequence of operation with this system every thing seems to be a secret witch I think is nonsense

 

[SkunkWerx's]

Like you said if there is a Glitch in the system while you were in hover yes I can see the Mavic doing exactly as you say -- GPS stays locked on a position and the Mavic is not there the Flight controller will tell the Mavic to move to the GPS locked position and at the same time your trying to control it
and getting nothing but Dead sticks
The way I see it you did two good things that day , you saved your Bird and Fixed the issue yourself
This is the way it should be -- DJI should give out more Info and more support instead of -- Oh your Mavic crashed it got scratched send it Back to us there's something wrong we will fix it
If I'm not understanding you correctly Please Correct me

 

[rydfree]

You must be a liberal.

You must be a liberal for thinking in any way that sounds like a liberal .

That's hopefully the dumbest thing I'll post all day but gotta consider what I'm answering . SMH

Good first post BTW . Off to a great start .

 

[AlanTheBeast]

The GPS "correction" notion is possible but if I were putting in such firmware I'd have reasonableness checks to guard against large step changes in GPS position resulting in a position adjustment.

IMO, the best thing to do first in a flyaway as described is to hit "up" stick first. It might not respond to horizontal stick, but it should go up on command at any time - that will save you from obstacles, perhaps.

Cities are bad locations for GPS. The urban canyons can easily initiate a GPS quite far from where the receiver is located and position changes to the good or bad can be sudden and large.

It really pays to takeoff in the most open area possible and to check the location on the display before firing up the motors.

 

[geigy]

Good tip on increasing altitude. In a pinch, every instinct is to bring the bird down and to safety, but there are fewer things to hit at a higher altitude, and fewer things to block the R/C signal so it's safer.

At times like these, switching to ATTI mode would be handy, but DJI does not allow the pilot to directly go into ATTI mode.

I agree with Alan that the drone should filter out large GPS changes, but it's a tough call. They obviously filter out small GPS errors with standard low pass filter techniques, but what about a large jump in GPS location? It's an interesting question. I have some thoughts on this: where the bird goes into ATTI mode with a large number of satellites but no GPS bars.