Lost all control and crashed

[supra59uk]

Hi All

I was asked by a club member to film some night flying aircraft at our club site
I set the quad up as normal, The first flight of about ten mins went well, I swapped out the battery for a new one then took the quad up again, About 15 seconds into the flight my green flashing lights turned red, The quad started drifting away from me quite erratically, i tried to drop the quad down and there was no control response know matter what I did with the sticks it was twitching all over the place and then did a final tip and ended up at the bottom of a very large pond next to my flying club, which can be seen on the map view this all happened within a one min flight, the distance travelled was about 50 to 75 meters i would guess.

One of the younger club members managed to retrieve the quad from the bottom of the pond, I removed the battery quickly, When i got home i removed the top then washed everything with warm clean water, It’s now in the drying out stage so i don’t know what the damage is to the electrics, gimbal and camera.

I’m pretty sure I have done the right thing by stripping it down and washing the dirty water off all the electronics, I used an hairdryer to dry it off, its now in the airing cupboard and been there for 3 days.

The craft was purchased in April 2017 from Clifton Cameras and is still under warranty, do i first take this up with them or DJI.

I wish i kept my phantom 3 pro now, that was solid as a rock has was my old Naza 2 on my 450.

I thought fly-aways was a thing of the past, Im totally shocked this happened with this newer tech especially with all the backup equipment it Has.
I have taken a look at the flight recording and there was a problem with the imu and then a compass error, Then the last one was a gimbal error.

17#
link to the flight record

https://www.phantomhelp.com/logviewer/53CR1WKC0E5G0L43LBTV/

Any advice welcome.

Supra59uk

 

[Meta4]

About 15 seconds into the flight my green flashing lights turned red, The quad started drifting away from me quite erratically, i tried to drop the quad down and there was no control response know matter what I did with the sticks it was twitching all over the place

I thought fly-aways was a thing of the past, Im totally shocked this happened with this newer tech especially with all the backup equipment it has.

Your flight record shows the characteristic compass and yaw errors that show up when you launch from a magnetically bad site.
Looking at your flight data, the first question I would ask is about the launch spot.
Was it on reinforced concrete or close to a lot of steel?

 

[sar104]

The compass errors really need the DAT file to diagnose, and clearly those caused the switch to ATTI mode at 16.3 seconds. However, you are incorrect that the aircraft stopped responding to stick input. If you look at the altitude vs. throttle data you will see the following:

From 20 seconds until the end of the flight, you applied full down throttle, which is why the aircraft landed - in the pond, unfortunately. But you landed it.

Looking at the pitch and roll data:

After the 16 second mark, when it switched to ATTI, notice that the pitch and roll values are driven purely by the stick inputs of elevator and aileron which, when added to the wind (out of the south) led to the northward drift.

Considering the aircraft heading (yaw):

As you can see, the yaw behavior throughout the flight was consistent with the rudder input.

The clear conclusion is that it switched to ATTI and was responding appropriately, but most likely you have not practiced flying in that mode and became confused.

That said, the switch to ATTI may or may not have been due to magnetic interference where you launched. The DAT file should answer that question. If it was a hardware issue with the magnetometers (the other possibility) then it is still worth pursuing DJI for a warranty claim.

Apologies for the Imperial units - only just noticed that you are in the UK.

 

[LarBear360]

Your flight record shows the characteristic compass and yaw errors that show up when you launch from a magnetically bad site.
Looking at your flight data, the first question I would ask is about the launch spot.
Was it on reinforced concrete or close to a lot of steel?

Just looking at the images, it doesn't appear to be paved, but are those solar panels. I wonder what's in that building.

 

[BudWalker]

Hi All

I was asked by a club member to film some night flying aircraft at our club site
I set the quad up as normal, The first flight of about ten mins went well, I swapped out the battery for a new one then took the quad up again, About 15 seconds into the flight my green flashing lights turned red, The quad started drifting away from me quite erratically, i tried to drop the quad down and there was no control response know matter what I did with the sticks it was twitching all over the place and then did a final tip and ended up at the bottom of a very large pond next to my flying club, which can be seen on the map view this all happened within a one min flight, the distance travelled was about 50 to 75 meters i would guess.

One of the younger club members managed to retrieve the quad from the bottom of the pond, I removed the battery quickly, When i got home i removed the top then washed everything with warm clean water, It’s now in the drying out stage so i don’t know what the damage is to the electrics, gimbal and camera.

I’m pretty sure I have done the right thing by stripping it down and washing the dirty water off all the electronics, I used an hairdryer to dry it off, its now in the airing cupboard and been there for 3 days.

The craft was purchased in April 2017 from Clifton Cameras and is still under warranty, do i first take this up with them or DJI.

I wish i kept my phantom 3 pro now, that was solid as a rock has was my old Naza 2 on my 450.

I thought fly-aways was a thing of the past, Im totally shocked this happened with this newer tech especially with all the backup equipment it Has.
I have taken a look at the flight recording and there was a problem with the imu and then a compass error, Then the last one was a gimbal error.

17#
link to the flight record

https://www.phantomhelp.com/logviewer/53CR1WKC0E5G0L43LBTV/

Any advice welcome.

Supra59uk

It would be better if we had the .DAT but, from the .txt, it's almost certain this was an incident caused by launching from a geomagnetically distorted location. At launch the .txt log indicates that the heading was -165.9 degrees. But, when elevator was applied at 7.467 secs the P4 moved in a westerly direction.

=================>

From this it's clear that the Yaw value was incorrect at launch. This is almost always caused by a geomagnetic distortion at the launch site (rebar in concrete, hood of a car, etc). It can also be caused by powering on the AC in a geomagnetically distorted location and then quickly moved to and launched from a better spot.

 

[supra59uk]

The compass errors really need the DAT file to diagnose, and clearly those caused the switch to ATTI mode at 16.3 seconds. However, you are incorrect that the aircraft stopped responding to stick input. If you look at the altitude vs. throttle data you will see the following:

View attachment 90474

From 20 seconds until the end of the flight, you applied full down throttle, which is why the aircraft landed - in the pond, unfortunately. But you landed it.

Looking at the pitch and roll data:

View attachment 90475

After the 16 second mark, when it switched to ATTI, notice that the pitch and roll values are driven purely by the stick inputs of elevator and aileron which, when added to the wind (out of the south) led to the northward drift.

Considering the aircraft heading (yaw):

View attachment 90476

As you can see, the yaw behavior throughout the flight was consistent with the rudder input.

The clear conclusion is that it switched to ATTI and was responding appropriately, but most likely you have not practiced flying in that mode and became confused.

That said, the switch to ATTI may or may not have been due to magnetic interference where you launched. The DAT file should answer that question. If it was a hardware issue with the magnetometers (the other possibility) then it is still worth pursuing DJI for a warranty claim.

Apologies for the Imperial units - only just noticed that you are in the UK.

 

[supra59uk]

Hi Guys I thank you kindly for taking a look at the log but there is some bits that don't make sense to me
mainly this From 20 seconds until the end of the flight, you applied full down throttle, which is why the aircraft landed

when I took the quad up it reached 50ft or so this is when I noticed the light turning red and it started to drift the first thing I did was drop the throttle right off to get the craft down to the ground it never dropped it just kept flying further away towards the pond I tried left and right move ments and full back to stop the drift nothing happened so why does the graph not show the down throttle before the drifting occurred

Further more the site where I took off from is in the middle of no where no concrete its all grass its our official flying club, which I fly there with all my models never had issues I'm not new to flying drones I had f450 with naza 2, Phantom 3 pro, Tbs Discovery Pro all with gps also
I have 2 x vortex pros racing quads non gps which I fly in manual and atti so you can hopefully understand my confusion, it doesn't make sense Please don't think I'm being argumentative because I'm not I do appreciate your comments.

 

[BudWalker]

Hi Guys I thank you kindly for taking a look at the log but there is some bits that don't make sense to me
mainly this From 20 seconds until the end of the flight, you applied full down throttle, which is why the aircraft landed

when I took the quad up it reached 50ft or so this is when I noticed the light turning red and it started to drift the first thing I did was drop the throttle right off to get the craft down to the ground it never dropped it just kept flying further away towards the pond I tried left and right move ments and full back to stop the drift nothing happened so why does the graph not show the down throttle before the drifting occurred

Further more the site where I took off from is in the middle of no where no concrete its all grass its our official flying club, which I fly there with all my models never had issues I'm not new to flying drones I had f450 with naza 2, Phantom 3 pro, Tbs Discovery Pro all with gps also
I have 2 x vortex pros racing quads non gps which I fly in manual and atti so you can hopefully understand my confusion, it doesn't make sense Please don't think I'm being argumentative because I'm not I do appreciate your comments.

The log shows that full down throttle started being applied at 20.183 causing the P4 to descend. At around 24.89 secs it had dropped to 0 meters (relative to the HP) and continued dropping until -1.5 meters - presumably the height of the pond.

The .DAT may offer some additional clues about the incorrect Yaw at launch. Was the P4 facing west at launch? Did you move the P4 after power on and immediately before launch as I described?

 

[sar104]

Hi Guys I thank you kindly for taking a look at the log but there is some bits that don't make sense to me
mainly this From 20 seconds until the end of the flight, you applied full down throttle, which is why the aircraft landed

when I took the quad up it reached 50ft or so this is when I noticed the light turning red and it started to drift the first thing I did was drop the throttle right off to get the craft down to the ground it never dropped it just kept flying further away towards the pond I tried left and right move ments and full back to stop the drift nothing happened so why does the graph not show the down throttle before the drifting occurred

Further more the site where I took off from is in the middle of no where no concrete its all grass its our official flying club, which I fly there with all my models never had issues I'm not new to flying drones I had f450 with naza 2, Phantom 3 pro, Tbs Discovery Pro all with gps also
I have 2 x vortex pros racing quads non gps which I fly in manual and atti so you can hopefully understand my confusion, it doesn't make sense Please don't think I'm being argumentative because I'm not I do appreciate your comments.

The FC switched to ATTI at 16.3 seconds, which started a slow drift. At that time you were level at 54 ft altitude. You went to minimum on the throttle at 18.6 seconds, and it immediately started to descend. You applied full back elevator at 20.9 seconds, but you also added right aileron and left rudder, which did not bring it back.

 

[sar104]

This is a somewhat interesting plot - comparing IMU course, GPS course and yaw.

The compass errors start at around 8 seconds on first significant horizontal movement. Forward elevator is applied, which the FC would expect to move the aircraft on a course of around -166° (SSW). Instead the aircraft moves on a course of -100° (W) - 66° off the apparent yaw heading. Note that the IMU course is between the two values - it's presumably trying to reconcile the conflicting data. That leads to the FC applying left roll (see post #3) and throwing the compass error. Whether that is magnetic interference or bad magnetometer data is hard to tell without the DAT file.

 

[sar104]

The log shows that full down throttle started being applied at 20.183 causing the P4 to descend. At around 24.89 secs it had dropped to 0 meters (relative to the HP) and continued dropping until -1.5 meters - presumably the height of the pond.
View attachment 90505

The .DAT may offer some additional clues about the incorrect Yaw at launch. Was the P4 facing west at launch? Did you move the P4 after power on and immediately before launch as I described?

The course data do suggest that the aircraft was facing west.

 

[BudWalker]

This is a somewhat interesting plot - comparing IMU course, GPS course and yaw.

View attachment 90506

The compass errors start at around 8 seconds on first significant horizontal movement. Forward elevator is applied, which the FC would expect to move the aircraft on a course of around -166° (SSW). Instead the aircraft moves on a course of -100° (W) - 66° off the apparent yaw heading. Note that the IMU course is between the two values - it's presumably trying to reconcile the conflicting data. That leads to the FC applying left roll (see post #3) and throwing the compass error. Whether that is magnetic interference or bad magnetometer data is hard to tell without the DAT file.

What is IMU course? I'm supposing it's computed from the values xSpeed and ySpeed and then applying Yaw. Is that OK since Yaw is known to be incorrect?

 

[supra59uk]

Hi Budwalker

No I turned the craft on where It took off from, I had already done one flight ten mins before this one with no issues.
if what you are saying is correct which I'm sure it is, The graph is wrong I lowered the throttle as soon as the drift started this was way before 20.182 I was not flying from my ipad screen I was flying line of site it was dark, the intension of the flight was to just hover at the take off position but just as I was getting to the height I was planning to film from this is when I noticed the green flashing lights go red, and it was at this point the craft started the drift towards the pond. It was from that moment on I zeroed the throttle and also pulled back on the other stick to correct the drift but it never responded to my stick movement. however has it got closer to the pond I did notice the red lights flickered to green for a split second and then back to red. when it was over the pond yes I still had my throttle at zero the craft sort of did a zig zag then tipped over and went into the pond I guess this was from about ten feet, I'm wondering if the Vos had something to do with the final flip?

Again thank you for your time

 

[supra59uk]

Can I also say you guys are amazing with the amount of knowledge you have being honest I'm totally lost with these logs

again thankyou all

 

[supra59uk]

Can I ask does these graphs correspond to what I'm saying happened in my mind ? to be honest I don't think DJI will warrant the claim
because I was stupid thinking I was doing the right thing stripping it and cleaning the salt water off

I must say I have always loved DJI stuff but this as put me off a bit

 

[sar104]

What is IMU course? I'm supposing it's computed from the values xSpeed and ySpeed and then applying Yaw. Is that OK since Yaw is known to be incorrect?

Right - I should have defined where that came from. I'm computing it just from VelocityX and VelocityY, since those are referenced to North and East, not the aircraft frame of reference, so the FC has already used yaw plus some kind of comparison to GPS data to calculate them.

 

[sar104]

Hi Budwalker

No I turned the craft on where It took off from, I had already done one flight ten mins before this one with no issues.
if what you are saying is correct which I'm sure it is, The graph is wrong I lowered the throttle as soon as the drift started this was way before 20.182 I was not flying from my ipad screen I was flying line of site it was dark, the intension of the flight was to just hover at the take off position but just as I was getting to the height I was planning to film from this is when I noticed the green flashing lights go red, and it was at this point the craft started the drift towards the pond. It was from that moment on I zeroed the throttle and also pulled back on the other stick to correct the drift but it never responded to my stick movement. however has it got closer to the pond I did notice the red lights flickered to green for a split second and then back to red. when it was over the pond yes I still had my throttle at zero the craft sort of did a zig zag then tipped over and went into the pond I guess this was from about ten feet, I'm wondering if the Vos had something to do with the final flip?

Again thank you for your time

I'm afraid that the probability that the data are wrong on the stick inputs and altitude is extremely small. You dropped the throttle from neutral to minimum about 2.5 seconds after the switch to ATTI. If you look at the stick inputs shown in the graphs, together with the actual course of the aircraft (the GPS course is the only trustworthy one) you will see why it move the way it did.

 

[sar104]

Can I ask does these graphs correspond to what I'm saying happened in my mind ? to be honest I don't think DJI will warrant the claim
because I was stupid thinking I was doing the right thing stripping it and cleaning the salt water off

I must say I have always loved DJI stuff but this as put me off a bit

I think that there is a good chance this is a warranty issue, but we really need to see the DAT file to know for sure. If you haven't sent the aircraft for repair yet can you extract and post it?

 

[supra59uk]

Thanks again for the help
no I still have the phantom here I will see what happens when I try to put the battery back in the damage is already done so nothing to loose
well I hope lol

 

[BudWalker]

Hi Budwalker

No I turned the craft on where It took off from, I had already done one flight ten mins before this one with no issues.
if what you are saying is correct which I'm sure it is, The graph is wrong I lowered the throttle as soon as the drift started this was way before 20.182 I was not flying from my ipad screen I was flying line of site it was dark, the intension of the flight was to just hover at the take off position but just as I was getting to the height I was planning to film from this is when I noticed the green flashing lights go red, and it was at this point the craft started the drift towards the pond. It was from that moment on I zeroed the throttle and also pulled back on the other stick to correct the drift but it never responded to my stick movement. however has it got closer to the pond I did notice the red lights flickered to green for a split second and then back to red. when it was over the pond yes I still had my throttle at zero the craft sort of did a zig zag then tipped over and went into the pond I guess this was from about ten feet, I'm wondering if the Vos had something to do with the final flip?

Again thank you for your time

There isn't much I can add regarding any discrepancy between the log and actual event sequence. I wasn't present for the flight and all I have is the log file. @sar104 has pretty much said anything I would add.

Regarding the launch site geomagnetic distortion issue: The material doesn't have to be large, e.g. it could be a washer if it were located directly under the compass. I'm assuming that the P4 is like my P3 and the compass is in the bottom part of the leg next to the launch surface. Moving the P4 1/4 inch could be enough to eliminate any adverse effects. The .DAT could help a lot.

What direction was the P4 facing at launch? Was it a westerly direction?