Does mavic air lose collision avoidance when it loses connection to R.C?

Mazdaman323lx · Jul 2, 2020

Greetings . Flew my newly purchased mavic air today and to cut long story short it , without warning l, ost connection to the controller , tried to return to home , decided after 10 seconds on the return leg not to , and drifted off into tree tops close by.
Does the collision avoidance not work when RC Connection is lost ?
I include a link the the flight log. Would appreciate any assistance in understanding what went wrong.
Did eventually recover the drone but have lost confidence to fly it again . Was nowhere near transmission towers and had 18 gps satelites at full bars.
Would bad connection from phone to controller via the side cable be a culprit?

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Any help advice appreciated

lannes · Jul 2, 2020

Are you talking about a MA or MA2 ?

sar104 · Jul 2, 2020

Mazdaman323lx said:
Greetings . Flew my newly purchased mavic air today and to cut long story short it , without warning l, ost connection to the controller , tried to return to home , decided after 10 seconds on the return leg not to , and drifted off into tree tops close by.
Does the collision avoidance not work when RC Connection is lost ?
I include a link the the flight log. Would appreciate any assistance in understanding what went wrong.
Did eventually recover the drone but have lost confidence to fly it again . Was nowhere near transmission towers and had 18 gps satelites at full bars.
Would bad connection from phone to controller via the side cable be a culprit?

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Any help advice appreciated

That's not quite what happened. It did lose connection at 207 seconds, and entered RTH mode. At 238 seconds the link was restored and it continued in RTH towards the home point until 254 seconds when you canceled RTH, rotated it through 180°, and applied left aileron to drive it into the trees.

Prismatic · Jul 2, 2020

sar104 said:
That's not quite what happened. It did lose connection at 207 seconds, and entered RTH mode. At 238 seconds the link was restored and it continued in RTH towards the home point until 254 seconds when you canceled RTH, rotated it through 180°, and applied left aileron to drive it into the trees.

The OP may have been unwittingly activating the sticks after the connection dropped; with his attention fully fixed on the drone's position--and hands idly resting on the RC--he may not have noticed that the connection was re-established.

"The devil finds work," they used to say, "for idle hands."

Dakarenduro · Jul 3, 2020

OP may also have lost orientation when RC reconnected. Was the drone facing him? if so left = right etc. just trying to give the OP an "out"

Mazdaman323lx · Jul 3, 2020

Thanks for the insight guys. The screen lost the the video link - went black and white and froze , then the dji 4 app shut down altogether. I had to restart the app , but by the time connection was re establishished it was in the trees. The return to home initiated while the connection was lost so I got no indication it was coming back to me . Steep learning curve with these devices but hope to continue undeterred.Thabks again

Dakarenduro · Jul 3, 2020

This is the Mavic Air 1 and not the MA2? I assume because you mention the "dji 4" app (Go4)?
I haven't had the go4 app shut down when flying my MA1 or the Mavic 2. But I have read of the MA2 "Fly" app shutting down on the forums.

Either way, if the app shuts off or freezes, you still can control (fly) the drone with the remote control. It's connection is independent of the phone app.

Really sorry for your crash.

Mazdaman323lx · Jul 3, 2020

Do you know what , I think thats what happened . When the app froze and cut out , I restarted it thinking the drone would just hover in place and I could reconnect as I had about 20 mins left on the battery. In my rush to relaunch the app and reconnect I think maybe I had my hand inadvertantly on the joystick . I thought you could only fly when the DJI app was live on your phone. Still I was able to recovered the drone after 2 hours of searching through chest high brambles , vines and thorns, Just wondering though , why did it hit the trees ? Shouldnt the collision avoidance have kicked in ?I had been flying in normal p-gps mode.

Prismatic · Jul 3, 2020

Mazdaman323lx said:
Do you know what , I think thats what happened . When the app froze and cut out , I restarted it thinking the drone would just hover in place and I could reconnect as I had about 20 mins left on the battery. In my rush to relaunch the app and reconnect I think maybe I had my hand inadvertantly on the joystick . I thought you could only fly when the DJI app was live on your phone. Still I was able to recovered the drone after 2 hours of searching through chest high brambles , vines and thorns, Just wondering though , why did it hit the trees ? Shouldnt the collision avoidance have kicked in ?I had been flying in normal p-gps mode.

Collision avoidance is on during RTH (your original question) and in P-mode (when the drone crashed). However, the Mavic Air does not have side sensors, so you can easily collide with objects if the drone is traveling to its left or right. The last plot in @sar104 's analysis shows exactly that orientation. I expect she went into the trees laterally, not head (or tail) on.

sar104 · Jul 3, 2020

Prismatic said:
Collision avoidance is on during RTH (your original question) and in P-mode (when the drone crashed). However, the Mavic Air does not have side sensors, so you can easily collide with objects if the drone is traveling to its left or right. The last plot in @sar104 's analysis shows exactly that orientation. I expect she went into the trees laterally, not head (or tail) on.

This is correct - as shown in that graph the aircraft flew sideways, to the left, into the trees.

Prismatic · Jul 3, 2020

Mazdaman323lx said:
Do you know what , I think thats what happened . When the app froze and cut out , I restarted it thinking the drone would just hover in place and I could reconnect as I had about 20 mins left on the battery. In my rush to relaunch the app and reconnect I think maybe I had my hand inadvertantly on the joystick . I thought you could only fly when the DJI app was live on your phone. Still I was able to recover the drone after 2 hours of searching through chest high brambles , vines and thorns, Just wondering though , why did it hit the trees ? Shouldnt the collision avoidance have kicked in ?I had been flying in normal p-gps mode.

I can just imagine your dismay at this realization. And I'm very glad you recovered your bird (scratched and dirty, but very happy, I'm sure!).

I suggest an exercise : Get a good GPS lock in a clear area and go hover 100m away. Now unplug the phone (or whatever smart device) from the RC. Keep your thumbs off the sticks, and watch what happens with the drone. (Spoiler: it remains hovering.) Now fly it around a bit, keeping it in sight of course, but entirely without the control app. In this way, you're proving to yourself that the smart device and app are not required to fly the drone. The app is an (incredibly helpful) add-on to the system, but the drone itself is actually oblivious to its existence, and relies entirely on the RC.

Now, plug the smart device back in and re-establish the video feed. Take a deep breath aaannd ... turn off the RC. Watch what happens with the drone. After a short wait, it will initiate a fail-safe Return-to-Home. (Note: the drone's response to loss-of-signal is configurable in the app, so you may want to check that setting before you power the RC down.) Before it gets home, restart the RC. It should reconnect with the drone fairly quickly; at that point, the drone will stop its RTH and await your command. If you do nothing, after a few seconds the RTH will resume. But if you begin manually flying again, the RTH will be cancelled.

Note the hidden gotcha, which actually sorta "got you": if you fail to notice that a connection has be re-established during a failsafe RTH, and then touch the controls, you can unwittingly cancel that RTH. More than one pilot has inadvertently done this; they come here wondering why their drone never returned home, and are stunned to learn that they themselves may have accidentally told it not to!

This builds your confidence in the reliability of the system so that, in the next emergency (which is a matter of "when", not "if") you'll know what to expect and react accordingly.

Frankfurter · Jul 3, 2020

@Prismatic
Thank you for the suggestion of this confidence-building exercise, very helpful!

Dakarenduro · Jul 4, 2020

Just a caveat to Prismatic's recommendation... there are 3 RTH scenarios. You should read all 3 in the manual.
Key part of RTH is if you are within X meters of the "home point" the unit will simply land. So if you are doing his scenario, follow his advice of 100m distance if that is possible.

Mazdaman323lx · Jul 4, 2020

Thank you to all for taking the time and effort to help me understand my mishap. Your suggestions and guidance is greatly appreciated to a noob like myself. Kudos to you all.

Mazdaman323lx · Jul 4, 2020

P.S Guys , I posted of the recovered footage of the crash on you tube . Came across a nice surprise while battling my way out of the overgrowth

Prismatic · Jul 4, 2020

Mazdaman323lx said:
P.S Guys , I posted of the recovered footage of the crash on you tube

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. Came across a nice surprise while battling my way out of the overgrowth