Phantom 4 Pro V2 Lost GPS and flew away

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Last night, one of our pilots was flying a mission using his Phantom 4 Pro V2, using Pix4dCapture when he lost his drone. He only launched the drone one time, but there are two flight logs for the day. I have looked at the flight data trying to find where it went, and I see that it was still reporting a position without any GPS signal, how can it do that? We have looked at its last reported position, as well as the area where it had the problems with the ESC. Does anyone have any ideas what could have happened, or where to look for the drone?

Here are the links to the two flights on AirData:


 

Meta4

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Last night, one of our pilots was flying a mission using his Phantom 4 Pro V2, using Pix4dCapture when he lost his drone. He only launched the drone one time, but there are two flight logs for the day. I have looked at the flight data trying to find where it went, and I see that it was still reporting a position without any GPS signal, how can it do that? We have looked at its last reported position, as well as the area where it had the problems with the ESC. Does anyone have any ideas what could have happened, or where to look for the drone?
The first flight shows the same problem that happened in the second flight.
It was temporary and the pilot brought the drone down before things got out of control.

This shows the flight data from the 2nd flight better than Airdata:

There was an issue that caused the flight controller to lose confidence in the GPS data.
It first showed up at 1:44.4 until 2:13.
It came good briefly and started again at 2:16.5.
The drone effectively had no GPS for the rest of the flight (although the flight data contains GPS position data after that point, it is not believable.
A test calculation I did with data later in the flight gave a speed of >100 mph.
The ESC issue Airdata reported was probably due to interpreting bad data rather than a genuine issue.

The pilot had no indication of speed and his distance showing in telemetry was false information.
Height data would have been accurate.
That left the Phantom in atti mode, still controllable but with no horizontal position holding.
It had no brakes and could be blown by the wind.

The pilot left the controls untouched until 2:40.6.
He gave some input with the joysticks throughout the flight until giving up at 9:16.7 with the drone 350 feet up, position unknown.

Because of the problem with GPS data, we have no idea where the drone really was or how fast it was drifting away.

If the Phantom was <1 year old, the data might be sufficient for a warranty claim with DJI.

This incident is quite a difficult one to solve.
I can't be much more help, but it might be a worthy puzzle for @sar104 to tackle.

He will probably need to see the .dat file from the phone/tablet.
Instructions for finding that are in here:
 

ianzone

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Is it possible to calculate battery remaining time at 9:16 when pilot give up with amount of wind speed and direction ,,if the wind stayed south east direction till it autoland or (crash),,,,,was just crazy idea I was having but I would go that way south east for a while if possible,,,,if it was traveling at >100mph if would have covered some ground,,yip just a thought,,,best of luck @Cori51.
Screenshot_20200619-191805_Chrome.jpg
 
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Thanks for the help everybody! The pilot says he only took off one time that day, so I'm not sure why there are two flights showing up. The drone is over 1 year old, but I will contact DJI and see what they say. This happened about 100 miles away from me, but I will see if I can make it up there to look for it about 3 miles downwind.
 
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ianzone

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100 MPH , holy smokes is that right ?

Unless it had 60mph tail wind I doubt it ,copyed that from above post,since the pilot gave up I presume it be drifting in atti mode at wind speed,,,,,this is a area dji should look into,,a failsafe RTH, because it only works when it has GPS,,it should work with or without GPS with a press on the RTH in these times,,toy drones have one key return and often dont use GPS,,phantoms which cost 30 times more dont work like that,,why is this ,,
 
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Meta4

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if it was traveling at >100mph if would have covered some ground
100 MPH , holy smokes is that right ?
No .. it's not right, it's a number I calculated using the (bad) GPS data that was being recorded.
The Flight Controller recognised that the GPS data was wrong and stopped using it.
Most position data for this flight is wrong.

The pilot says he only took off one time that day, so I'm not sure why there are two flights showing up.
The drone is over 1 year old, but I will contact DJI and see what they say. This happened about 100 miles away from me, but I will see if I can make it up there to look for it about 3 miles downwind.
It was just one flight but the flight log was broken into two.
DJI will want to charge for any analysis for an out of warranty drone, and I doubt they could tell much.
I wouldn't put too much hope or effort into searching without some better data to show a likely search area.
@sar104 might be able to extract something from the gyroscope data (?), but he would need the .dat file I mentioned in post #3.
I'll message him to see what he can do.
 
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I just looked through the folders, but I think there is a .dat file because this flight was done with Pix4d Capture.
 
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The first flight shows the same problem that happened in the second flight.
It was temporary and the pilot brought the drone down before things got out of control.

This shows the flight data from the 2nd flight better than Airdata:

There was an issue that caused the flight controller to lose confidence in the GPS data.
It first showed up at 1:44.4 until 2:13.
It came good briefly and started again at 2:16.5.
The drone effectively had no GPS for the rest of the flight (although the flight data contains GPS position data after that point, it is not believable.
A test calculation I did with data later in the flight gave a speed of >100 mph.
The ESC issue Airdata reported was probably due to interpreting bad data rather than a genuine issue.

The pilot had no indication of speed and his distance showing in telemetry was false information.
Height data would have been accurate.
That left the Phantom in atti mode, still controllable but with no horizontal position holding.
It had no brakes and could be blown by the wind.

The pilot left the controls untouched until 2:40.6.
He gave some input with the joysticks throughout the flight until giving up at 9:16.7 with the drone 350 feet up, position unknown.

Because of the problem with GPS data, we have no idea where the drone really was or how fast it was drifting away.

If the Phantom was <1 year old, the data might be sufficient for a warranty claim with DJI.

This incident is quite a difficult one to solve.
I can't be much more help, but it might be a worthy puzzle for @sar104 to tackle.

He will probably need to see the .dat file from the phone/tablet.
Instructions for finding that are in here:

I’m just curious, but what is “bad GPS data,” what does it look like, and what do you compare it to to tell that it’s bad?

I have only seen GPS data that is less accurate than I may need, and I don’t know what data from a malfunctioning GPS receiver looks like.

Or, maybe it’s “bad” because there weren’t enough satellites visible to get a reliable fix???

Thanks!
 
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ianzone

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Um bad data good data the wind say which way it went 👉,it wont fly into or against wind in atti mode so grab the dog and go for a walk
 

Meta4

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I’m just curious, but what is “bad GPS data,” what does it look like, and what do you compare it to to tell that it’s bad?
I have only seen GPS data that is less accurate than I may need, and I don’t know what data from a malfunctioning GPS receiver looks like.
Or, maybe it’s “bad” because there weren’t enough satellites visible to get a reliable fix???
There are always enough satellites, unless a significant part of the sky is blocked by obstacles.

In this case, the bad GPS data looked just like good GPS data.
But the numbers weren't believable.
The flight controller compared the position data supplied by GPS with data from the gyro sensors and it did not agree.
I checked the speed by calculating the distance between the recorded location of the drone over 20 seconds of flight and the calculated speed was >100 mph.
That was obviously very wrong, so I agree with the Flight Controller and think the GPS data was bad.
 
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sar104

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The first flight shows the same problem that happened in the second flight.
It was temporary and the pilot brought the drone down before things got out of control.

This shows the flight data from the 2nd flight better than Airdata:

There was an issue that caused the flight controller to lose confidence in the GPS data.
It first showed up at 1:44.4 until 2:13.
It came good briefly and started again at 2:16.5.
The drone effectively had no GPS for the rest of the flight (although the flight data contains GPS position data after that point, it is not believable.
A test calculation I did with data later in the flight gave a speed of >100 mph.
The ESC issue Airdata reported was probably due to interpreting bad data rather than a genuine issue.

The pilot had no indication of speed and his distance showing in telemetry was false information.
Height data would have been accurate.
That left the Phantom in atti mode, still controllable but with no horizontal position holding.
It had no brakes and could be blown by the wind.

The pilot left the controls untouched until 2:40.6.
He gave some input with the joysticks throughout the flight until giving up at 9:16.7 with the drone 350 feet up, position unknown.

Because of the problem with GPS data, we have no idea where the drone really was or how fast it was drifting away.

If the Phantom was <1 year old, the data might be sufficient for a warranty claim with DJI.

This incident is quite a difficult one to solve.
I can't be much more help, but it might be a worthy puzzle for @sar104 to tackle.

He will probably need to see the .dat file from the phone/tablet.
Instructions for finding that are in here:

I'm afraid that this one is going to remain a mystery. The aircraft switched to ATTI due to the GpsPositionNoMatch flag, not because of a lack of satellites.The txt log doesn't generally continue to report position when that happens, so I wonder if it is a slightly non-standard implementation of the DJI SDK.

That said, I think the position reporting is incorrect, since it leads to the following velocity record:

Delta_V.png


That has the aircraft moving SE at 62 m/s, or around 140 mph. The winds at 110 m were nowhere near that speed, and so it really isn't physically possible, which in turn means that the position data are worthless. All we can say is that it likely drifted some distance SE, and then will have autolanded on loss of uplink (default failsafe in ATTI mode).
 

ianzone

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Man that's just technical way of saying what I put in #4,,;)oh well I dont mind being a nobody
Me dont need technical data anyway,,common sense say which way it went
It's over there by that bit of dirt behind the bush next to 2nd blade of grass resting on a gold nugget
 
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Hope it gets found.
This looks like a good reason to always fly VLOS, then if you lose GPS, you just fly back visually.

I sometimes practise this by taking the drone a few hundred metres away, switching to ATTI and spin it on its axis so I don't know its orientation. You can quickly work out its orientation, even if windy, by flying 'forwards' a few seconds and observing the effect. I is reassuring to find that this is no big deal and even landing are not bad in ATTI, if not super windy.
 

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