Drone Falls out of the sky while doing cell tower inspection. GPS_Hotspot?!?!?!

[tronesdrones]

Hello Everyone!!!
Recently I was doing a cell tower inspection in the middle of nowhere New Mexico and experienced my first ever problem with a Phantom 4 Pro V2.0. I have done roughly 1465 cell tower inspections over the last year and half and have never had this happen to me before. So I was a little shocked when I kept getting errors all of a sudden and look up and see that my drone is going end over end until it smashes onto a rock and continues to travel down the mountain.
Here is the flight data from AirData GPS_Hotspot
Now I have never seen this option before with the term of GPS_Hotspot and was a little confused as to what it was in the flight data. After doing several Web searches I am still not confident as to what it really is.
SOOOO.... If you know what this is and can explain it, that would be great!!!!
I was up to date on software, used a POI, was in 5.8 mode. I also have the option of stopping motors turned off in the setting so it wasn't an emergency shut down! Kp index was 1.3

 

[Shoot4fun]

Welcome to the forum! This is one for the smart guys... That ain't me!

Brad

 

[sar104]

GPS_HotPoint (flycState = 0) is POI mode, so that was normal, until towards the end, when NavHealth went to zero and the IMU fusion solution for position and velocity went bad.

The FC started reporting compass errors at 420 seconds, although there is no obvious compass problem until 512 seconds, at which point the FC switches to ATTI.

That should have cured the flight control problem, but it didn't - the FC completely lost attitude and altitude control:

I really need to see the mobile device DAT file (FLY728.DAT) to understand what happened:

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[Meta4]

SOOOO.... If you know what this is and can explain it, that would be great!!!!

Here's what your flight data really looks like: DJI Flight Log Viewer - PhantomHelp.com
There's nothing unusual until 8:29.9 when the drone starts to roll.
Prior to that the roll angle had been 0° - +/-3° but at 8:29.9 it shows 8.1° and within half a second the drone has rolled upside down and is falling and tumbling.
All the error messages following that are due to the tumbling and are not indicating causes of the crash.
The drone doesn't spin which would indicate loss of a prop or motor.

 

[sar104]

I am a bit confused about your location - that was just south of Pyramid Lake in Nevada - nowhere near New Mexico. Were you lost?

 

[Shoot4fun]

@tronesdrones
(Told ya they was smart....) ?

 

[Trackerputnam]

Just a thought! As described, it sounds as if you may have encountered an unforeseen obstruction (wire) of some kind!

 

[tronesdrones]

I am a bit confused about your location - that was just south of Pyramid Lake in Nevada - nowhere near New Mexico. Were you lost?

I might have been!!! I was on several projects in the last 3 weeks and got them confused.

 

[tronesdrones]

GPS_HotPoint (flycState = 0) is POI mode, so that was normal, until towards the end, when NavHealth went to zero and the IMU fusion solution for position and velocity went bad.

View attachment 113534

The FC started reporting compass errors at 420 seconds, although there is no obvious compass problem until 512 seconds, at which point the FC switches to ATTI.

View attachment 113532

That should have cured the flight control problem, but it didn't - the FC completely lost attitude and altitude control:

View attachment 113533

I really need to see the mobile device DAT file (FLY728.DAT) to understand what happened:

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

That is exactly what I was seeing. It was a self support tower and there were no guyed wires. Up until this tower I haven't had any issues with the compass and always do a compass calibration before each flight.

 

[tronesdrones]

Just a thought! As described, it sounds as if you may have encountered an unforeseen obstruction (wire) of some kind!

It was a self support tower and there were no guyed wires or any obstructions seen while doing pre-flight walk/planning.

 

[tronesdrones]

GPS_HotPoint (flycState = 0) is POI mode, so that was normal, until towards the end, when NavHealth went to zero and the IMU fusion solution for position and velocity went bad.

View attachment 113534

The FC started reporting compass errors at 420 seconds, although there is no obvious compass problem until 512 seconds, at which point the FC switches to ATTI.

View attachment 113532

That should have cured the flight control problem, but it didn't - the FC completely lost attitude and altitude control:

View attachment 113533

I really need to see the mobile device DAT file (FLY728.DAT) to understand what happened:

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

I will get that data later this afternoon for you.

 

[NM_Quad]

What does "GPS Position - No Match" mean on the flight record? Never seen that one before. Kinda like the onboard GPS suddenly got corrupted or confused?

 

[sar104]

What does "GPS Position - No Match" mean on the flight record? Never seen that one before. Kinda like the onboard GPS suddenly got corrupted or confused?

It seems to mean that the GPS position data are inconsistent with the IMU computed position, which is generally a result of compass problems having introduced errors in the IMU yaw value.

 

[Meta4]

What does "GPS Position - No Match" mean on the flight record? Never seen that one before. Kinda like the onboard GPS suddenly got corrupted or confused?

It turns up in lots of flight records but usually makes no difference to a normal, safe flight.
In this case it turned up while the drone was tumbling to the ground.
It's a result of the crash rather than a possible cause.

 

[Meta4]

I haven't had any issues with the compass and always do a compass calibration before each flight.

Any particular reason for that?
It's completely unnecessary.

 

[BudWalker]

GPS_HotPoint (flycState = 0) is POI mode, so that was normal, until towards the end, when NavHealth went to zero and the IMU fusion solution for position and velocity went bad.

View attachment 113534

The FC started reporting compass errors at 420 seconds, although there is no obvious compass problem until 512 seconds, at which point the FC switches to ATTI.

View attachment 113532

That should have cured the flight control problem, but it didn't - the FC completely lost attitude and altitude control:

View attachment 113533

I really need to see the mobile device DAT file (FLY728.DAT) to understand what happened:

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

The switch to ATTI was caused by navHealth dropping to 3 which, in turn, was caused by a decrease in numSats.

Still doesn't explain the subsequent loss of attitude and altitude control.

 

[jlrsn]

This is one that I'd like to see the actual cause of!!!