I flew a waypoint mission recently that I have flown many times before without issue, but this particular time, it decided to initiate an RTH midway through the mission, at the furthest point away from home point,  The drone is out of controller range for most of this waypoint mission, so I don't have any flight data availabe on the controller to analyze.  I forgot to download the dat file from the drone before it was overwritten by later flights.  


When the drone was on its way back to home point, it seemed to have run into a obstacle or wall that isn't really there.  The whole flight was a good 600ft AGL and was over surburban areas, so no super tall office buildings or the like.  When it supposedly hit a barrier or obstacle, it started going away from the home point for a little while before turning back and facing the homepoint and continue flying back sucessfully to the homepoint.  Becuase of this opposite direction detour, it came back home with just 13% left, luckily it didn't trigger forced landing out of controller range.

I double-checked the map on the DJI screen to see if there were any restricted no fly zones or blue authorization zones and didn't see any in the flight path.  So I'm not sure why it ran into this weird glitch

" The drone is out of controller range for most of this waypoint mission, so I don't have any flight data availabe on the controller to analyze. The whole flight was a good 600ft AGL and was over surburban areas, so no super tall office buildings or the like. "

Ahhhh I do love these posts by sensible pilots,

"I forgot to download the dat file from the drone before it was overwritten by later flights. "  Doesn't that mean you flew an awful lot today, and have a fair stock of batteries, that I have seen a drone's DAT space tends to be good for 15 or so full battery flights, have they reduced it on the Mavic 3 ? Can the mavic 3's DAT's be read.

" it came back home with just 13% left, luckily it didn't trigger forced landing out of controller range."
That would have been a perfect demonstration of why I think waypoint flight beyond control range are a bad idea.

If you don't want to run the risk of that happening then don't fly flights such as this one.
If you insist on flying such flights then I would say its part of the risk that yu have to accept.

Could it have triggered failsafe behaviour involving a retrace of a portion of the preceding flight ?

Sean-bumble-bee Posted at 4-11 17:09
" The drone is out of controller range for most of this waypoint mission, so I don't have any flight data availabe on the controller to analyze. The whole flight was a good 600ft AGL and was over surburban areas, so no super tall office buildings or the like. "

Ahhhh I do love these posts by sensible pilots,

Yes, I understand the risk of out of range waypoint flying, but I enjoy testing out the capability of waypoint flight missions and how advanced the current generation drones are.

This particular incident was almost two months ago and didn't make it a habit to download the aircraft dat files periodically, which is my fault given the high risk waypoint missions I like flying.  Since this incident I have flown many times more and by the time I thought to check the aircraft dat files using the DJI assistant software, this particular flight was no longer there.  The oldest flight I can see was from mid March and this flight was the end of February.  

I haven't heard of this retrace failsafe behavior.  What exactly is it?  But to answer your question, the particular route it did prior to heading straight back to home was not part of any previous waypoint flight plans.

Hi

Interesting issue.

At 14 secs in flight drone into RTH, so guess heading after the yaw turn is direct straight line heading to Homepoint.
At 1m28s drone yawed right smoothly for about 5 seconds, doesn't look for an 'obstacle' but for a barrier.
Drone tries to fly along that barrier.
At 2m22s again slow right turn, imo following the barrier line.

As i understand it correctly this part of the flight no connection with the RC, so yaw turns not made by you.

cheers
JJB

Sean-bumble-bee Posted at 4-11 17:09
" The drone is out of controller range for most of this waypoint mission, so I don't have any flight data availabe on the controller to analyze. The whole flight was a good 600ft AGL and was over surburban areas, so no super tall office buildings or the like. "

Ahhhh I do love these posts by sensible pilots,

I'm on a  crap tablet at the moment and it is not easy to check the pdf manual, i suggest you have a read of the fail safe portion of the manual to see whether or not the mavic 3 performs a retrace and the explanation of a retrace. Of course this has the added complication of " continue " presumably being set for the waypoint mission.

Why so high, "a good 600ft AGL" ?

Wasn't that an illegal AGL ?

Sean-bumble-bee Posted at 4-12 05:17
I'm on a  crap tablet at the moment and it is not easy to check the pdf manual, i suggest you have a read of the fail safe portion of the manual to see whether or not the mavic 3 performs a retrace and the explanation of a retrace. Of course this has the added complication of " continue " presumably being set for the waypoint mission.

Why so high, "a good 600ft AGL" ?

Well, I meant good in the sense it's above all obstacles for this particular flight mission and in case it does failsafe RTH and decides to go to preset RTH height, the drone should return without running into anything.

In terms of FAA legal, well.....

JJB* Posted at 4-12 00:04
Hi

Interesting issue.

After taking your post into consideration, it does it seems that this could be a possibility of being a barrier of some sort.

But the only real barrier that would cause the drone to stop in a red NFZ or a blue authorization zone.  There is a blue authorization zone around the area where it performed this abnormal maneuver, but the blue zone wasn't in it's path at all and I made sure to set the flight waypoints away from it.

asiangear Posted at 4-12 22:22
After taking your post into consideration, it does it seems that this could be a possibility of being a barrier of some sort.

But the only real barrier that would cause the drone to stop in a red NFZ or a blue authorization zone.  There is a blue authorization zone around the area where it performed this abnormal maneuver, but the blue zone wasn't in it's path at all and I made sure to set the flight waypoints away from it.

Hi,

It is a puzzle for me too, but the way your drone behaves in that RTH does look like it flys against some kind of barrier.

cheers
JJB

Purposely flying a way point mission, or any flight for that matter, out of radio controller range over a populated area, and above the FAA legal altitude of 400' AGL would probably be considered a 'Careless and Reckless' operation by the FAA.  Of course if you have a P107 Certificate, you would know that.

While I applaud your testing the limits of your SUAV, you may want to consider doing it in a remote area, that way if your drone runs out of power and does a controlled (or uncontrolled) decent on top of persons or property, no innocent people are injured.  Manned aircraft cannot legally fly lower than 500' over populated areas, so potentially wrapping your drone around a fixed wing manned aircraft at 600' would not work in your favor either.  Even if you have insurance, they would probably 'Run for Cover' and deny any claim based on statements you have made in this thread, and in a public forum.  Of course the FAA would probably thank you for making their job easy, especially if the aircraft you were operating has remote ID.

I see you have 17 satellites in view on your screen shot, and that is sufficient to take-off and mark your home point, however you may want to consider satellite signal degradation as a possible reason for your aircraft to be confused as to where it was in the airspace as it was trying to execute a RTH.

Fly Safe.







  



While I applaud your intentions to test your flying machine

Hi there. Let me forward this to the relevant team to check. I will keep you posted. Thank you for your patience.

Hi there. Upon being checked by the relevant team. They said it seemed the aircraft detected an obstacle by mistake during the RTH, this phenomenon may happen sometimes. If this happens again, please check the notes below:
1. Please check if there is a strong light emitting in the direction where a mistaken obstacle detection is reported.
2. Does the aircraft report an obstacle when flying in a fixed direction? If so, please check if there are buildings, trees, and scenes with repeated texture and grid lines in the environment.
3. Make sure the firmware is updated to the latest. If yes, try refreshing it using the DJI Assistant 2.
I hope this helps. Have a nice day.

How far from Home had the drone traveled at the point at which RTH was engaged?  Was it windy?  If it was relatively far, my thought is the drone may have calculated it only had enough power to RTH.  This would cause it to abort the mission & head for home.  Unfortunately for drones using Fly there is no toggle to disable this behavior.

As to the odd behavior where it turned away for quite some time then headed for Home, I have no explanation.  Are you certain the initial RTH was actually an RTH, or might you have inadvertently touched the screen & added an unintentional Waypoint?

Sean-bumble-bee Posted at 4-11 17:09
" The drone is out of controller range for most of this waypoint mission, so I don't have any flight data availabe on the controller to analyze. The whole flight was a good 600ft AGL and was over surburban areas, so no super tall office buildings or the like. "

Ahhhh I do love these posts by sensible pilots,

Retrace would not come into play if the drone was flying a Waypoint mission where the "On Signal Loss" behavior was set to "Continue".  Since he intended on flying beyond RC contact this would necessarily be the case.

For the OP, Retrace is where on signal loss the drone will retrace it's flight in an effort to reacquire RC contact.  It usually only retraces 50-100 meters or so, & not all models do this.  The Mavic 2 does it.  You'll have to check the documentation for the Mavic 3 to see if it does this too?  It would not seem to be applicable in your case either way.