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Hi everyone, this is my first post. So I don't know what happend today since I use my Mavic Air since 2018. Before this day my Mavic Air was crashed 4 times, but luckly it still working.

Today I was work on filming my friend's project. At the last session that need use drone footages, I planned to recording backward, the altitude not so high from ground but my drone position was above a river and will passing a brigde. I already measure the straight with my eyes and theres no obstracle I have to worry and I'm use Cinematic Mode. Then I move my Mavic Air backward. But for some reason my drone went crazy, it move turn left and I wasn't control it to turn left. I was shocked cause this is happened to me for the first time. I know it will fall down, but I don't want it fall into the river, then I move it to ground area. But it went more crazy, my Mavic Air move quick forward while I control it to backward. Then it crashed and hitted a tree. The back body were crushed, the camera was pop out and back leg motor was lost.

I was so confused why this is happened, theres no wind at the place and no signal tower. Is anybody have a same thing like me?
 

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Hi everyone, this is my first post. So I don't know what happend today since I use my Mavic Air since 2018. Before this day my Mavic Air was crashed 4 times, but luckly it still working.

Today I was work on filming my friend's project. At the last session that need use drone footages, I planned to recording backward, the altitude not so high from ground but my drone position was above a river and will passing a brigde. I already measure the straight with my eyes and theres no obstracle I have to worry and I'm use Cinematic Mode. Then I move my Mavic Air backward. But for some reason my drone went crazy, it move turn left and I wasn't control it to turn left. I was shocked cause this is happened to me for the first time. I know it will fall down, but I don't want it fall into the river, then I move it to ground area. But it went more crazy, my Mavic Air move quick forward while I control it to backward. Then it crashed and hitted a tree. The back body were crushed, the camera was pop out and back leg motor was lost.

I was so confused why this is happened, theres no wind at the place and no signal tower. Is anybody have a same thing like me?
We need the mobile device .DAT log for this ... it's located in the device you flew with in the same place as the .TXT log you've attached above but in a sub-folder there called MCDatFlightRecords. The .DAT log for this flight ends with FLY008.DAT

Retrieve it & attach it in a new post here ...
 
But for some reason my drone went crazy, it move turn left and I wasn't control it to turn left. ... But it went more crazy, my Mavic Air move quick forward while I control it to backward. Then it crashed and hit a tree.
Here's what that flight data looks like:

The problem starts at 2:15.6 when you went hands-off on the sticks after having the stick pushed full forward + right in cinematic mode.
The drone pitched back 44 degrees, which started it flying backwards quite quickly.

At 2:17.2 it collided with an obstacle.

It's not clear what caused the drone to accelerate as there is no corresponding joystick input.
I was so confused why this is happened, theres no wind at the place and no signal tower. Is anybody have a same thing like me?
Wind wouldn't cause this incident anyway unless your drone had lost GPS, but it had good GPS at the time.
Neither would a mobile phone tower - they don't cause uncontrolled flight.
 
Last edited:
What does "Strong Aircraft Interference" @ 2:16.9 mean? What causes that?
 
What does "Strong Aircraft Interference" @ 2:16.9 mean? What causes that?
That is usually WiFi disturbance on the AC location ...

Nothing so far from the .TXT log, which mostly contain the telemetry data, gives any answer to what happened ... that's why the .DAT log is needed as that log contains the raw sensor & motor data.

All we can do so far is to speculate ...

We need the correct DAT log which ends with FLY008.DAT to be able to say more.
 
Here's what that flight data looks like:

The problem starts at 2:15.6 when you went hands-off on the sticks after having the stick pushed full forward + right in cinematic mode.
The drone pitched back 44 degrees, which started it flying backwards quite quickly.

At 2:17.2 it collided with an obstacle.

It's not clear what caused the drone to accelerate as there is no corresponding joystick input.

Wind wouldn't cause this incident anyway unless your drone had lost GPS, but it had good GPS at the time.
Neither would a mobile phone tower - they don't cause uncontrolled flight.

Sounds like a power / telephone line / cable of some type or something he did not see visually. They seem to creep up on drones and like to take them down.
 
Sounds like a power / telephone line / cable of some type or something he did not see visually. They seem to creep up on drones and like to take them down.
Nothing in the .TXT log indicate anything like that ...

No large AC movements is recorded until 0,5sec before the log ends as seen by the pitch, roll & yaw graphs below ... & those most probably originate from the crash.

1617118845103.png


But the wrong tilt direction compared to the travel direction is more indicative ... here below symbolized by the yellow bar & the by me, drawn orange line-arrow that shows the travel direction from where the incident starts. This can only happen if a AC is blown away ... & that wasn't the case here.

1617119292524.png

We also see larger velocity differences between the IMU & the GPS just where it starts ... that usually points to IMU problems.

1617119576705.png

So far it's to little data to be able to say that this was a pilot error ...
 
Here's what that flight data looks like:

The problem starts at 2:15.6 when you went hands-off on the sticks after having the stick pushed full forward + right in cinematic mode.
The drone pitched back 44 degrees, which started it flying backwards quite quickly.

At 2:17.2 it collided with an obstacle.

It's not clear what caused the drone to accelerate as there is no corresponding joystick input.

Wind wouldn't cause this incident anyway unless your drone had lost GPS, but it had good GPS at the time.
Neither would a mobile phone tower - they don't cause uncontrolled flight.
I think when I crossing the bridge, bridge has a lot of steel construction. I just realize it yesterday
 
I think when I crossing the bridge, bridge has a lot of steel construction. I just realize it yesterday
Have you found the correct .DAT log yet? It's the one ending with FLY008.DAT...

Usually shortly flying into magnetic disturbance will not cause thing's like this ... but the log will clearly show the case.
 
Maybe this one
Yep... that is the correct one.

This incident hasn't anything to do with:
-Powering up in a magnetic disturbed area ... as the IMU is initialized to the compass direction & no deviations occurs after take-off

-Flying near some metal construction, like a bridge ... as the magnetic field strength is pretty constant during the whole flight.

-Hitting something... as no sudden AC movements or acceleration values is generated when the incident starts.



Instead this is completely due to that the IMU(1) (which is the one that is used) ...fails at 119,2sec into the flight & leaves the flight controller without knowledge in which direction the AC is pointing.

If we start by showing this graphically on the sat. image ...

The first picture is from 119,2sec into the flight ... a tad before the incident starts.

The green line is the flight path according to the used IMU(1), the red according to the unused IMU(0).

We also have some colored bars going out from the "star"-shaped markings which indicate the AC position.

-The Yellow shows the yaw heading according to the compass ... both IMU compass readings are yellow as in reality the MA1 only have 1 compass.
-The blue bar shows the yaw heading from the unused IMU(0)
-The red bar shows the yaw heading from the used IMU(1)

Everything looks good here ... both IMU's are indicated to be in approx. the same location & both IMU's yaw direction agrees with each other & the compass.

(Click on all pictures & charts below to make them larger)
1617179877625.png

Now here ... only 2 sec later the picture is very different. The unused IMU(0) agrees still well with the compass direction & follow the red path which is rather smooth. But the IMU(1) which the AC is using have suddenly changed the yaw direction massively (red bar) ... the green path generated from IMU(1) is also jagged which also indicate that something isn't right there.

1617181334153.png

Showing off this in graphs below ... & try to isolate what it is that's failing.

First we stack up both IMU yaw together with the gyro ... both gyros + the IMU(0) yaw agrees well. But the IMU(1) yaw (black graph) indicate something odd starting at 119,2sec. (The graphs is laid out in the chart "unwrapped"... meaning not bound to a +/- 180 or 360 degree axis, instead freely adds & subtract degrees infinitive as the AC rotates).

1617182132036.png

Then we below stack up both IMU yaws together with the compass (on a +/- 180 degree axis) ... + another yaw measuring coming from the VPS sensor on the AC belly that visually measure the yaw (red graph). Again we see that the only value that disagrees is the one coming from the IMU(1) (blue graph).

By this we can conclude that the IMU(1) have failed due to some reason, either due to a computational error or permanently.

1617182574527.png

Below we in the red graph can see the total deviation between the actual direction the AC have & what the IMU(1) think's it have ... at maximum it's above 123 degrees.

This means that the AC will use completely wrong motors to correct it's position ... when the flight controller sense the need of correcting the position due to for instance affected by outside forces (like wind) it in this case use the wrong opposite motors ... & by that generate an even larger positional error ... tries again & again and a error loop is created which makes the AC fly away uncontrollably. The fly away path is rather straight ... which is what to expect when the heading deviation is close to 180 degrees.

1617182902294.png

And as a last check ... below a read off from the DAT event log which also clearly indicate whats shown in the charts above.

1617183348390.png
 
...
Instead this is completely due to that the IMU(1) (which is the one that is used) ...fails at 119,2sec into the flight & leaves the flight controller without knowledge in which direction the AC is pointing.
...
Excellent work, @slup, and for @Willy Cita Jaya, it's half-good news. I mean, he at least has the comfort of knowing that this was not a piloting error of any kind. It is a shock to have your bird destroyed, but worse to think you made a terrible mistake. I know this because I have lived it. ?

This event is unsettling. My own MA is the same age ...
 
Sorry to hear about your drone. When was the last time it was crashed please? If crashing has damaged a mems chip in imu. There is a proceedure for rapping/tapping on the drone that may unjam it. Then test fly low in an open grassed space. See anything you dont like, land it
 

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