Yesterday evening 2020-05-14 I flew a round when it was dark.
And!
Same check as always before taking off!
*** ALWAYS CHECK WEATHER CONDITIONS ***
1. Fully charged batteries (craft, controller, phone)
2. Memory card OK
3. Removed gimbal protection
4. Folded wings
5. Checked ALL props
6. Spin a little lightly on all engines
7. Power up craft
-------------------------------------------------- -
8. Screwed on sticks
9. Deployed antennas
10. Opened phone holder
11. Plugged in USB cable to cell
12. Plugged in USB cable to controller.
13. Power up controller
14. Waiting for craft and controls to connect
15. Checking the status of GPS satellites
16. Check status transmission
17. Check other status
18. ALWAYS change to Mode C
19. Always recalibrate IMU
TAKEOFF PERMITTED
20. Taped to open take off window
21. Hold down take off window
22. Mini starts normally and rise about 1m. and hover ...
Suddenly Mini started to wobble little ...
... and just run away
I didn't touch any sticks
Anyway I tried to "EMERGENCY PROPELLER STOP" no response and Mini drifted away, Finally after 10m altitude 1m I got Mini landed in the middle ot the road and run like hell to catch her.
Switched everything off, restarted all status.
Now I also checked that the battery was ok mounted in the craft.

So here we go again ...
Mini up in the air about 15m and suddenly a red led started to flash!
No WARNING on screen!
Landed Mini and started over again and this time I also restarted my phone.

Mini up in the air for about 15-min. no problems.
NO errors
NO red led warnings.
NO wobbles.

Tonite started bad and the were 2 Error saying Motor Blocked!
I cheked everything, motors and props and finally I was flying!

Tonite I checked log files, and guess what?
Accidents day 2020-05-14 was not loged !!!!!
I also can't find the log file "Motor blocked"!

I would contact DJI and find out why. Very odd no log file.

Totally I agree with Vlas

didn't see anything about compass, you sure you didn't mistake the always recalibrate imu with the compass?? because actually the imu should not be touched, so far with 60 flights i haven't calibrated the imu a single time. And the compass ultimately on every flight. By the explanation of how it flew away it seems like compass issue, but lack of log is quite strange.

Seems like the New Air2 got lots of problems.

sbonev Posted at 5-17 08:25
didn't see anything about compass, you sure you didn't mistake the always recalibrate imu with the compass?? because actually the imu should not be touched, so far with 60 flights i haven't calibrated the imu a single time. And the compass ultimately on every flight. By the explanation of how it flew away it seems like compass issue, but lack of log is quite strange.

I agree, I had to calibrate IMU a few times (2x or 3x), while compass needs to calibrate almost every new take-off spot.
I would suggest power on remote first, then power on AC away from possible interference (metal, electricity) and always check compass heading on map.

@The Witless:  " ...  I flew a round when it was dark. "  With only downward sensors that depend on light for positioning, your first problem is Vlas/Vlos which may have mitigated or otherwise compromised other navigation necessities.  How does it fly in the daylight?

I think you problem was caused by  insufficient light so vps at low altitude could not get anything to lock on to so drifted.

I’m not sure from what you write if you crash landed or not. If you did you should calibrate IMU and gimbal, in fact because of drifting it’s probably a good idea to calibrate anyways.

Motor problem check to see if the are moving freely and try restarting and test at low altitude, during daylight.

That's an add combination of events, it sounds weird to me that the Emergency Propeller Stop didn't work as one motor not responding properly I believe should enable the option.

I suggest you activate Emergency Propeller Stop at all times (disable only during emergency option).

Then I also suggest you DON'T use it unless necessary. Preferably set the Auto-RTH for descend and in case the event repeats itself initiate a manual descent, should there be signal loss it will still land on its own.

Since the red LED indicator was flashing it was probably an IMU error. I suggest you go on and calibrate the IMU and compass the next start up, taking care to be far from any "contaminant" like reinforced concrete or metal surfaces and objects.

Motor block errors shouldn't be ignored. You should be able to retrieve the .txt log from your DJI » dji.go.v5 » FlightRecord folder.

I also suggest you blow inside the motors with canned or compressed air and possibly lubricate the tiny spindles with some silicone based oil (or PTFE).

virtual Posted at 5-17 08:56
I agree, I had to calibrate IMU a few times (2x or 3x), while compass needs to calibrate almost every new take-off spot.
I would suggest power on remote first, then power on AC away from possible interference (metal, electricity) and always check compass heading on map.

THX 4 reply!
As I describe it in my first post:
- always calibrates at new takeoff
- spare time for AC battery, it always takes longer for AC to get started up
- always check interference (metal/electricity) when checking the weather
- maybe I missed the compass

WebParrot Posted at 5-17 09:37
@The Witless:  " ...  I flew a round when it was dark. "  With only downward sensors that depend on light for positioning, your first problem is Vlas/Vlos which may have mitigated or otherwise compromised other navigation necessities.  How does it fly in the daylight?

I'm Bitless OK!

Think I flew more at night than daytime, never any problems before.
Day time perfectly OK.

hallmark007 Posted at 5-17 10:04
I think you problem was caused by  insufficient light so vps at low altitude could not get anything to lock on to so drifted.

I’m not sure from what you write if you crash landed or not. If you did you should calibrate IMU and gimbal, in fact because of drifting it’s probably a good idea to calibrate anyways.

THX 4 reply!

Has always moved position at insufficient light.
I didn't crash, AC flew uncontrolled in C-Mode and landed perfectly in the middle of the street.

All problems started after updating the FW!

The Bitless Posted at 5-17 13:21
THX 4 reply!

THX 4 reply!

Has always moved position at insufficient light.
I didn't crash, AC flew uncontrolled in C-Mode and landed perfectly in the middle of the street.

All problems started after updating the FW!

That sounds very similar to my experience in my first attempt to fly at night. I was in a big hurry to get aloft because I was trying to record a satellite train by video. I did not wait for enough sats and it drifted quickly across the street and crashed into a bush. It showed the motor blocked message in the log file but I never saw it again. And I was successful later that night after waiting for enough sats. My bad.

The Bitless Posted at 5-17 13:21
THX 4 reply!

Has always moved position at insufficient light.

I think it was a matter of no VPS lock because of low light. As I said test in good light. If compass was problem you would have had warning.

Don’t put any lubricant oils sprays or anything else in your drone.

hallmark007 Posted at 5-17 13:38
I think it was a matter of no VPS lock because of low light. As I said test in good light. If compass was problem you would have had warning.

Don’t put any lubricant oils sprays or anything else in your drone.

Always put another position IF=warning low lights!
Why should I put lubricant oils spray OR anything ELSE in my drone?
Maybe I missed the compass!
I'm not that stupid, OK!

I have now found a log file that belongs to the accident day.
- How do I get that map from MAPBOX?

hallmark007 Posted at 5-17 13:38
I think it was a matter of no VPS lock because of low light. As I said test in good light. If compass was problem you would have had warning.

Don’t put any lubricant oils sprays or anything else in your drone.

Amazing that it landed right between two cars ;-)

The Bitless Posted at 5-17 14:13
Always put another position IF=warning low lights!
Why should I put lubricant oils spray OR anything ELSE in my drone?
Maybe I missed the compass!

Post #10 advised you to put lubricant in your drone....

Link below if you want to upload logs.

http://www.phantomhelp.com/LogViewer/Upload/

GaryDoug Posted at 5-17 14:40
Amazing that it landed right between two cars ;-)

THX 4 reply!

Exactly, right between!

But chk the H -2m in the pix!

You shouldn't be calibrating IMU unless prompted, that's ridiculous. Compass has nothing to do with this issue either lol. The drone will drift slightly in poor light but not what you are talking about. Sounds more like operator error than anything else. Maybe fly more in daylight and get to know what you are doing first before flying at night.

deathsquad Posted at 5-17 15:41
You shouldn't be calibrating IMU unless prompted, that's ridiculous. Compass has nothing to do with this issue either lol. The drone will drift slightly in poor light but not what you are talking about. Sounds more like operator error than anything else. Maybe fly more in daylight and get to know what you are doing first before flying at night.

I flew more at night than daytime, never any problems before.
Day time perfectly OK.

The Bitless Posted at 5-17 16:15
I flew more at night than daytime, never any problems before.
Day time perfectly OK.
https://www.youtube.com/watch?v=KOYC_yrudOg

Flight log......

Very nice roll, smooth moves.
I think your videos would benefit from the new 24 fps (allowing slower shutter speeds) and some good gain in the shadows. MM footage despite the lowish bitrate is very good at retaining shadows detail.

I have literally calibrated the IMU twice since I had the drone in December. It's not like the compass. If there isn't an issue you should leave it alone. Like I said earlier, calibrating the IMU every flight is ridiculous and chances are you made an error calibrating the IMU on an uneven surface, holding it or at a slight angle causing a drift issue in flight.

........... Never mind, I was way off. Deleted

The Bitless Posted at 5-17 14:53
THX 4 reply!

Exactly, right between!

After further reading, calibration of the IMU every flight is frankly ridiculous and totally unnecessary, I will leave below my opinion on how IMU works and when and why you might need to calibrate.

Incidentally I don’t believe calibration of the IMU caused your problem , but would like to see log.

IMU "Inertial measurement unit" .

As far as I see it, IMU calibration on a level surface updates a table of values the flight controller software uses as a reference for a level stationary hover. From there the craft responds predictably to flight commands.  It also likely measures any sensor noise and thermal drift so that these technical imperfections are accounted for when using IMU sensor data in flight. - this is likely why there must be no vibrations during the calibration process.


Bad IMU calibration could cause drift and attitude issues as the flight controller fights to hold the craft in what it thinks is the correct attitude as opposed to the correct physical attitude.


The IMU usually has 2 types of sensors – angle and acceleration and in turn 3 sensors of each type measuring in the X,Y and Z axis. These sensors can, through vibration, aging, impact etc, drift in their response over time and thus an IMU calibration will establish a new reference for the IMU’s level/stationary state that the flight controller can work with to restore stable flight.


Think of calibration as the bringing back into line the measured craft attitude with the true physical craft attitude.


As to how often an IMU calibration is needed, Refer to your manual ; certainly after any impact or if there are suspicions the craft can’t hover in a level attitude in a windless environment.

The Bitless Posted at 5-17 13:10
THX 4 reply!
As I describe it in my first post:
- always calibrates at new takeoff

To check compass heading in map is good to detect possible interference but it probably was not the problem this time - compass error is very dramatic accident. I calibrate only when requested by app (or if I had a suspicion but it never happened).