Fly Away

[brianmcg]

Flying a P4 with the latest version of DJI Go 4.

Three flights today with the last one ending in grief.

First flight of the day went off without incident. No issues at all.

After that, I had two fly-aways and have never had anything like this before. Until today, it has always been a dream to fly.

First fly away occurred at altitude. The P4 was in normal mode. It started becoming more difficult to control and then headed south at speeds topping out at over 50mph. I was able to regain control be hitting the return to home button. It slowed, stopped and then return home as expected.

Prior to the third flight, I checked the IMU and compass and they were both very good. Took off with a good GPS fix in normal mode and within a minute it was again flying south at low altitude at over 54mph prior to contacting several trees followed by the ground.

Bad damage to one arm and perhaps more inside. Video recorded until the battery ejected.

Any ideas would be appreciated. I would be happy to upload data if you can tell me what you need. This is the very first incident I have had with this machine and I would like to find out what the issue is asap.

Thanks!

 

[brianmcg]

First fly away link Airdata UAV - Flight Data Analysis for Drones

 

[brianmcg]

Fatal fly away link Airdata UAV - Flight Data Analysis for Drones

 

[JohnnyD913]

What where your warnings. You had 11 warnings in non fatal flight and I believe 4 in fatal flight. Check those and maybe that will help narrow things down. Look like the lake you where flying over had a very reflective light from the sun. Maybe your v.p.s got corrupted. I'm no pro at these type things but maybe something I suggested will help. Very sorry to hear about your bird. Hopefully dji will cover it.

 

[brianmcg]

What where your warnings. You had 11 warnings in non fatal flight and I believe 4 in fatal flight. Check those and maybe that will help narrow things down. Look like the lake you where flying over had a very reflective light from the sun. Maybe your v.p.s got corrupted. I'm no pro at these type things but maybe something I suggested will help. Very sorry to hear about your bird. Hopefully dji will cover it.

All warnings in the non-fatal flight log were "[compass]data exception (In Flight) please switch to atti mode if craft behave abnormally (Using)". They all appear in the log about one second prior to my hitting the RTH button and about 10 seconds after the loss of control.

The same error was reported once in the fatal log and occurred about 12 seconds prior to the LOC.

Video of RTH-recovered mission (non-crash)

Video of crash

.

 

[JohnnyD913]

That sux. I'm no expert on flying over water cuz I've heard and read we aren't suppose to. Something to do with v.p.s. My guess is that system couldn't figure what type of terrain it was over. There are videos explaining this and I will see if I can find a link. Also in the manual it talks about flying over water and the hazards. I see video all the time of water flights but for all I know the v.p.s. Was turned off. That's my guess, v.p.s

 

[brianmcg]

That sux. I'm no expert on flying over water cuz I've heard and read we aren't suppose to. Something to do with v.p.s. My guess is that system couldn't figure what type of terrain it was over. There are videos explaining this and I will see if I can find a link. Also in the manual it talks about flying over water and the hazards. I see video all the time of water flights but for all I know the v.p.s. Was turned off. That's my guess, v.p.s

That's interesting because there is a point in the logs where the VPS Altitude value suddenly goes to 0 and then comes back after a while. Has anyone else heard about this being an issue?

 

[tevek]

That's interesting because there is a point in the logs where the VPS Altitude value suddenly goes to 0 and then comes back after a while. Has anyone else heard about this being an issue?

Flying over water at that height and in those light conditions can play havoc with the VPS, causing it to be unstable/unpredictable. I fly a lot of the time over a lake where I live and disable VPS if flying at 10 mtrs or less as the drone starts to wander all over the place, low light makes it even more so. You had a warning regarding switching to Atti mode due a compass exception which suggests there was something else going on.

 

[MarcusKeeler]

If I get one Compass related error in a flight I'm coming home immediately.

Compass related issues, be they user error (Bad or no calibration) or system failure, are the chief cause of a GPS bird "flying away".

 

[brianmcg]

If I get one Compass related error in a flight I'm coming home immediately.

Compass related issues, be they user error (Bad or no calibration) or system failure, are the chief cause of a GPS bird "flying away".

Thanks! That's good advice and I will certainly do that in future, but I'm still puzzled at why RTH arrested the first fly-away and then returned to launch point as expected.

 

[Meta4]

All warnings in the non-fatal flight log were "[compass]data exception (In Flight) please switch to atti mode if craft behave abnormally (Using)". They all appear in the log about one second prior to my hitting the RTH button and about 10 seconds after the loss of control.

The same error was reported once in the fatal log and occurred about 12 seconds prior to the LOC.

Airdata isn't going to show you much useful info.
To find out what happened in your case go to https://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight records for the flights in question.
Come back and post a link to the report it provides and someone here might be able to analyse it and give you an understanding of the cause of the incident.

 

[brianmcg]

Airdata isn't going to show you much useful info.
To find out what happened in your case go to https://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight records for the flights in question.
Come back and post a link to the report it provides and someone here might be able to analyse it and give you an understanding of the cause of the incident.

Flight log from fly-away with recovery via RTH: DJI Phantom & Mavic Flight Log Viewer - PhantomHelp.com
Flight log from fly-away and crash: DJI Phantom & Mavic Flight Log Viewer - PhantomHelp.com

 

[reddyvv]

The first fly away happened above VPS altitude or so it seems. I suspect it's some other hardware issue

 

[Duchunter]

In both logs youve got one cell performing a bit less than the rest but its a different cell in each log. First log its the 4 cell, the second log its the second cell. I dont have any idea if that had any part of the crash I just noticed it and am pointing it out.

 

[Duchunter]

All warnings in the non-fatal flight log were "[compass]data exception (In Flight) please switch to atti mode if craft behave abnormally (Using)". They all appear in the log about one second prior to my hitting the RTH button and about 10 seconds after the loss of control.

The same error was reported once in the fatal log and occurred about 12 seconds prior to the LOC.

Video of RTH-recovered mission (non-crash)

Video of crash

.

Holly heck, ive never seen a p4 angle over like that. It has to be hauling but at that angle! What it was doing before it flew away is what mine was doing a few nights ago. It was tripping out big time.

 

[wataero]

I had something similar to your 2nd flight, I started seeing landing strut and had no directional control. Fortunately I had setup RTH and it worked. After landing I did a gimbal calibration procedure and have not seen a recurrence. 2 lessons I learned from this,
1 - Always set-up RTH, altitude, OA,... and precision landing and never move from hover after talking off until Home Point Set message.
2 - If you ever see strut in camera, something is wrong, hit RTH button immediately - whatever is wrong it will not get better by itself.
I know this is no comfort for a crashed bird, been there...

 

[xmtrdr]

That's interesting because there is a point in the logs where the VPS Altitude value suddenly goes to 0 and then comes back after a while. Has anyone else heard about this being an issue?

It is funny you mention the altitude goes to zero. I have had this happen twice with out incident and I was in the process of coming in for a landing. I wonder if it may be an issue with the satellites the drone is reading? I have had regualr GPS units do the same with shifting elevations readings!

 

[brianmcg]

The top speed in both fly aways exceeded 50mph even though the drone was in P-GPS mode which is supposed to be limited to 20-25mph.

The GPS record doesn't seem to indicate any issues there. The compass calibration might have contributed to the fly-away based on the directional control performance just prior but I can't see how that by itself would result in the kind of loss of control I saw.

 

[xmtrdr]

The top speed in both fly aways exceeded 50mph even though the drone was in P-GPS mode which is supposed to be limited to 20-25mph.

The GPS record doesn't seem to indicate any issues there. The compass calibration might have contributed to the fly-away based on the directional control performance just prior but I can't see how that by itself would result in the kind of loss of control I saw.

I had a scary experience once and found that taking the extra time to calibrate the IMU's , Compasses, and Gimbal all seem to nearly eliminate most problems, I did have my tablet lock up and lost visual and thought I lost control of the drone. Turning off the controller set it to RTH mode and it came back safely after 5 scary minutes.

 

[ussvertigo]

Similar experience, happened only once in year I've had it. Once I took off and got a little altitude it behaved like yours, took off wide open toward some buildings, could not steer but could climb and just missed the top of the building and then out of sight. I hit rth and she came back, but acted a little screwy when hand catching. Cause turned out to be heavy rebar reinforced pilling under the area I was in. Grassy area with small trees, wide sidewalk right at the rivers edge. I had compass error before starting, moved to another area, no error readings before miss hap, then later put in same spot to check and this time it picked up the stuff under ground by compass error.