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Dangerous Bug in Litchi App
2638 9 2017-5-4
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redline870
lvl.2
United States
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I work at a University and manage a UAS/Drone research lab. We have been using the Litchi app for some time now, and have had a lot of success using the pre-programmed GPS waypoint feature. While flying today I recently discovered a very bad bug in the app.

In past missions, if something doesn't look right or if it's getting to close to an obstacle due to wind, I have always been able to pause the mission and manually fly it away from the obstacle. Today we were flying close proximity missions next to buildings using the DJI XT thermal camera and observing heat loss. The aircraft used was a stanard Inspire 1. The wind started blowing the drone towards the building and I paused the mission to fly it away but there was no control, absolutely nothing. I couldn't go in any direction, it was not responding to ANY control inputs. I quickly held the return-to-home button which overrode the mission and flew up and away from the building. I canceled the RTH when the aircraft was well away and then had full control.

I wasn't sure if this was a one time issue so I powered everything down, iPad included, and powered everything up again. I programmed a higher altitude mission that would allow me to experiment and see if the problem happened again, which it did. Every time it's flying a pre-programmed GPS waypoint mission, if the mission is paused, there is no control over the aircraft, it just sits in the same spot hovering. If you hold the RTH button and then cancel the mission, you can regain control. This is too lengthy of a procedure for regaining control of the aircraft so I decided it was too dangerous and decided to manually fly the rest of the session. I got back to the university and tried it on a new Inspire 1 Pro, with a different controller, and using my iPhone 7 plus. Same issue with completely different equipment, no control when the mission is paused.

I just wanted to bring this bug to everyones attention so no one crashes their aircrafts. Hopefully Litchi will resolve the problem in future updates, but until then I will not be using the app. Why cant DJI just implement the ability to pre program GPS waypoints? It blows my mind that they do not provide this feature with DJI GO!

2017-5-4
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Mark Guille
Captain
Flight distance : 2031818 ft
Guernsey
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My instinct when flying autonomously would be to flick the switch to atti mode if something was amiss, did you try this?
Thanks for the heads-up.

Mark G.
2017-5-4
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redline870
lvl.2
United States
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Mark Guille Posted at 2017-5-4 09:32
My instinct when flying autonomously would be to flick the switch to atti mode if something was amiss, did you try this?
Thanks for the heads-up.

I did not try using Atti mode, that is a good suggestion though. I will try and let you know what happens.
2017-5-4
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Mark Guille
Captain
Flight distance : 2031818 ft
Guernsey
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redline870 Posted at 2017-5-4 11:15
I did not try using Atti mode, that is a good suggestion though. I will try and let you know what happens.

Let us know. If the problem persists in atti mode, then we have a serious issue.

Mark G.
2017-5-4
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redline870
lvl.2
United States
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It's raining as always here in NY so unfortunately I will not be able to test today. I did receive a response from Litchi stating that this is not a bug, and they said you must switch to Atti mode to regain control. They also said this is how it has always been...? I know for a fact that in previous missions I was able to pause the mission, control the aircraft manually, and then hit play to pick up the mission where I left off.

Another weird thing that happened that I forgot to mention: A couple weeks ago we were performing a mission following a creek with 62 waypoints, 54 downstream and 8 for the return home. I had actions set at waypoints 1-54 to take a picture so we could digitally stitch them together. The Inspire flew almost the entire 54 downstream with no issue, but then skipped 4 waypoints (51-54), turned around, and followed the remaining waypoints (55-62) back home. Thinking to myself that perhaps there was too many waypoints, I landed the aircraft, altered the mission by deleting the first 39 waypoints, then tried it again, and it did the same thing. This time the mission only had 23 waypoints but it still skipped the 4 waypoints it missed before, only now those same waypoints were numbered 12-15 instead of 51-54.

Has anyone else experienced an issue like this? Is there something that I am doing wrong?
2017-5-5
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R&L Aerial
Captain
Flight distance : 298100 ft
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United States
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use bug spray, let set for a minute then use compressed air to blow bug spray residue and dead bugs out of your drone. Works great!
2017-5-5
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Rescue 1
lvl.2
Flight distance : 73950 ft
United States
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Interesting bug, I don't think it is a bug but just a program design so that there would be no external interference with the saved program once the mission was started.  Going to ATTI mode would be the only way to over ride the locked drone, just as the RTH button press told the craft to go home.  I'll watch for this..  thanks
2018-5-16
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redline870
lvl.2
United States
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Rescue 1 Posted at 2018-5-16 07:58
Interesting bug, I don't think it is a bug but just a program design so that there would be no external interference with the saved program once the mission was started.  Going to ATTI mode would be the only way to over ride the locked drone, just as the RTH button press told the craft to go home.  I'll watch for this..  thanks

This is an old thread. They've fixed any issues I've had. You have 2 options, either pause the mission in the app, or slide the flight mode switch to any position other than "F". If you pause the mission, you can resume where you left off, if you slide the switch to a different position you need to restart the mission from the beginning.
2018-5-16
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Zbounce
Second Officer
Flight distance : 181125 ft
Luxembourg
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Thanks! You may have saved someone a lot of grief.
2019-2-16
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mixchief
First Officer
Flight distance : 160646 ft
United States
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Zbounce Posted at 2-16 07:37
Thanks! You may have saved someone a lot of grief.

Actually going into GPS mode would be a little safer if there is wind blowing the craft in te=he direction of a structure, Atti the craft will immediately let the wind push it every which way and if you re not faster than the wind .......bang!
2019-2-16
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