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International Date Line - any experience crossing this with a 2Pro?

redge57

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Hi, recently I flew towards the IDL on a planned short flight in Taveuni, Vanua Levu, Fiji. On hitting a longitude of 179.999997 the drone stopped and would not move laterally in any direction, but could rotate, ascend and descend. This was what I observed on the screen map - the distance reading was 101 m and did not vary even when I used forward controls and speed registered up to 40kmh. The shown position on the map also did not move. The drone was not visible at all and following the loss of battery power, contact was lost. Given that this was over water, I assumed it was lost at sea. I had heeded precautions regarding flight over water and made settings accordingly.

I have reported to Dji and await their response to flight details submitted, together with all other details.

Any experience in flight near IDL and any resulting mishaps? I have found nothing in Dji literature regarding flights near / on IDL and believe there is no accommodation for GPS anomalies in software / firmware.

Thanks
 

RayOZ

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Ouch. I guess there's so few countries that sits on that line, DJI did not test their software for that scenario. Probably should've tested this while over land.
 

Meta4

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Hi, recently I flew towards the IDL on a planned short flight in Taveuni, Vanua Levu, Fiji. On hitting a longitude of 179.999997 the drone stopped and would not move laterally in any direction, but could rotate, ascend and descend.

Any experience in flight near IDL and any resulting mishaps? I have found nothing in Dji literature regarding flights near / on IDL and believe there is no accommodation for GPS anomalies in software / firmware.
If you were in Fiji, you were nowhere near the International Date Line.
Your issue would be with the 180° east (or west) meridian.


If you were close enough to fly to the line from one side, crossing to the other side and flying from there would provide interesting information.
This was what I observed on the screen map - the distance reading was 101 m and did not vary even when I used forward controls and speed registered up to 40kmh.
The shown position on the map also did not move. The drone was not visible at all and following the loss of battery power, contact was lost.
There is no information here that can help determine what caused the loss of your drone.
It's hard to imagine it could be caused by bumping into 180° east.
On hitting a longitude of 179.999997 the drone stopped and would not move laterally in any direction, but could rotate, ascend and descend.
Any direction? You couldn't back away from the line?
I had heeded precautions regarding flight over water and made settings accordingly.
There are no settings that would make a flight over water any safer.
All you can do is to avoid flying into the water.
I have reported to Dji and await their response to flight details submitted, together with all other details.
DJI are not very good at communicating details or explaining flight incidents.
If you want to find out what happened, you should go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
 
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redge57

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Ouch. I guess there's so few countries that sits on that line, DJI did not test their software for that scenario. Probably should've tested this while over land.
Yep, .....Hindsight is an exact science :(
 

yousaidthat

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And not to go too far off topic, anyone flown their drone across the equator?
 

Meta4

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And not to go too far off topic, anyone flown their drone across the equator?
Crossing the equator shouldn't be any different than crossing any other line of latitude.
Crossing 180° east potentially has the issue of changing the date which won't happen crossing any other line of latitude or longitude.
 
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RayOZ

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I don't know if date is the issue or the calculated location/speed. Value is going from -180 to +180. It won't be a problem with crossing the equator.
 

gnirtS

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Crossing the equator shouldn't be any different than crossing any other line of latitude.
Crossing 180° east potentially has the issue of changing the date which won't happen crossing any other line of latitude or longitude.
It gets its date/time from GPS which isnt in the "human" format so it hasnt crossed anything of the sort.

Unless they have some terrible software routine where it first converts the GPS timestamp to a human readable format and THEN uses that for buggy code i cant see how it could do that.

As above, the log file will be very interesting.
 
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redge57

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If you were in Fiji, you were nowhere near the International Date Line.
Your issue would be with the 180° east (or west) meridian. Correct, my mistake - thanks.


If you were close enough to fly to the line from one side, crossing to the other side and flying from there would provide interesting information. Indeed, however not done.

There is no information here that can help determine what caused the loss of your drone.
It's hard to imagine it could be caused by bumping into 180° east. I now have used AIRDATA to analyse the log - some interesting results

Any direction? You couldn't back away from the line? No, not possible in any lateral direction. Distance from home reset to 0 upon long. 179.999995.

There are no settings that would make a flight over water any safer.
All you can do is to avoid flying into the water.

DJI are not very good at communicating details or explaining flight incidents.
If you want to find out what happened, you should go to DJI Flight Log Viewer | Phantom Help.


Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.

Interesting results from DJI Flight Log Viewer (somewhat different to Airdata) - at 45.7s I managed a speed of 1,079.6mph - must be a
record! GPS Position NoMatch. Flight go Viewer shows distance from home as 341ft thereafter and Airdata is reset to zero.

Airdata indicates final long. position as being -375.770695 - ??

Thanks for your assistance - any further insight based on analysis would be great. I hope to get a response from DJI in the next 2 days.
 

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redge57

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Instead of a screen shot, can you post actual data so we can see what actually happened during the flight?
I've imbedded 2 links to look at the analysis by Airdata and DJI Flight Log Viewer - can you gat tho these? First time user - apologies.
 

Meta4

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I've imbedded 2 links to look at the analysis by Airdata and DJI Flight Log Viewer - can you gat tho these? First time user - apologies.
Sorry .. part of your reply was in the wrong part of the post so was hidden.
I've just found it and will get back after looking into it.
 

Meta4

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I've imbedded 2 links to look at the analysis by Airdata and DJI Flight Log Viewer - can you gat tho these? First time user - apologies.
This is very unusual and quite interesting but very unfortunate for you.
The hidden flight data is: DJI Flight Log Viewer - PhantomHelp.com
It shows you bumping into the 180° meridian.
Normally when you run into one of DJI's invisible walls, you can't fly through them but you can easily back off and fly anywhere else.
You bumped into this invisible wall at 0:45.
The GPS location at that time was -16.79197232 179.9999967 at a height of 31 metres.
Right up to the last data recorded at 24:39.4, the GPS position did not change at all despite your efforts to move the drone to go anywhere.
The battery eventually ran out and the drone was lost just 100 metres from where you launched.
You were able to rotate the drone with the rudder control and point the drone in any direction.
You were able to climb and descend as well.
But nothing you tried would move the drone from the point where it was stuck.

This is definitely a case for DJI.
It does appear that there's something faulty in their programming and that crossing the 180° meridian has set it off.
I'd be very interested to see if @sar104 or @BudWalker can shed any light on what's happened.
 

Meta4

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There's something quite strange going on in this flight.
Although the GPS position never changes after hitting the wall and the GPS Speed shows zero after 0:45, your IMU is registering horizontal speed in response to your inputs with the right joystick.
It's as if the GPS has stuck.
At 0:45.5, just after hitting the wall you see the message: Switched to Backup IMU
The GPS Position NoMatch messages that follow, are usually meaningless.
At 0:45.6 there is a momentary indicated speed of 482.6 metres/sec with corresponding crazy speeds showing for Velocity Y & Velocity Z.
These figures are a glitch and the drone did not move that fast.
But the pitch data suggests that the drone did not stop when it "hit the wall" and kept going.

On hitting a longitude of 179.999997 the drone stopped and would not move laterally in any direction, but could rotate, ascend and descend. This was what I observed on the screen map - the distance reading was 101 m and did not vary even when I used forward controls and speed registered up to 40kmh. The shown position on the map also did not move. The drone was not visible at all and following the loss of battery power, contact was lost.
Looking at your description, you say the drone was out of sight, yet the distance shown was only 100 metres away?
I'm wondering if it was perhaps somewhere else and it was moving as the IMU and pitch data indicates?
This is also supported by he IMU speed data corresponding to your joystick inputs.
But the GPS position was locked at -16.79197232 179.9999967 which caused the screen map position to look frozen.
Do you remember what you saw on screen?
Did it look like the drone was flying, did the view change?


 
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Meta4

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With more head-scratching and staring at data, I think that your drone's GPS froze as you passed through the 180° meridian.
The drone kept flying and responding to your joystick inputs.
But you weren't watching when this happened and were confused by the false position and distance the app was showing you.
If you had been watching the drone, you should have been able to bring it back as the data indicates it was responding appropriately to your controls and crossing the 180° meridian had no effect on the drone's flying - just the GPS.
RTH would have not worked, but manual flying using the screen for guidance would have been unaffected.

This is definitely a strange flight and there aren't many places on land where it's possible.
It looks like something DJI never anticipated or corrected in their programming.
It would be interesting to test - but only keeping the drone close and over land.
 

gnirtS

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This is looking like a definite DJI replacement here.
Looks like they have some horrendous coding where longitude cant wrap without completely crashing the navigation software.
School boy level but it appears thats whats happened.

Its going to be something like a variable sign or similar.
 
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