I had just landed my P4 Pro and the low-battery failsafe took over.   I could not stop the rotors and I believe the aircraft attempted to return home but did not ascend into the air, presumably because I had the left stick all the way down in an attempt to stop the rotors.  Instead, it dragged along the ground for a bit, tipped over, went down a bank, into a river and over a waterfall.  The aircraft is lost.

Before deciding to spend another $1500 on a DJI drone I'd like to know if there's a way to override the failsafe.  Again, the aircraft had just landed and was stopped on the ground.  But I could not stop the rotors.

Thanks,

rgames

Thanks for the tip on RTH button w/ left stick down - didn't know that trick but that would have saved it.

Maybe it did think it was still moving and that's why it wouldn't let me kill the rotors - not sure why the sensors got confused, though, it was a typical landing on a flat spot.   The failsafe did kick in within three seconds of landing.  In fact, it probably wasn't even a second after coming to a complete stop.  Maybe that's a scenario that the failsafe algorithms don't account for - seems more likely than a sensor problem.

rgames

Wow that is really bad luck, rgames.


Next time, you might consider hand-catching when you're trying to land in such tight quarters.  

Sorry for your loss.

I just read an addition to the latest revison was the ability to kill the motors by left stick down and to the right(CSC)..... while holding the RTH button down!....WARNING KILLS MOTORS IN FLIGHT

Didn't lose the drone, but I too had a tip over on landing, I since have learned and practiced the kill procedure.  I also found out early that once the battery gets critically low, the P4 may not respond to the controls as expected.  Again, no damage when I learned this, but now, to be safe I am always back home and landed at 20 %.

dianea Posted at 2017-2-9 15:51
I just read an addition to the latest revison was the ability to kill the motors by left stick down and to the right(CSC)..... while holding the RTH button down!....WARNING KILLS MOTORS IN FLIGHT

dianea is exactly right.   This is an emergency protocol.  Very sorry to hear about your drone.  Worst feeling in the world.
Unfortunately it looks like you did everything wrong, and I don't mean to sound mean,  I hate when people get on here and say negative things.  I know you already feel like crap so I won't pile on.  First off,  YOU MAY BE ABLE TO FIND YOUR DRONE.  IF you still have your remote,  you can see the last place your drone was active through your user log.  Now if it truly is in a stream and somehow washed ashore while on,  go look for it!! It's worth a try.  The navigation system is really good!!
So here your mistake for next time.  If your drone was trying to Return Home and you pushed downwards,  instead of returning home it did exactly what you said.  Next time set your RTH to well above the highest point around you. If your failsafe comes on, do not panic!!!  Never panic and keep cool.  Most times when your failsafe comes you will be 100 % fine.   
So if you did this correctly this is how it would have gone.  Failsafe activates,  a message appears that your drone is returning to its home point.  From there it will ascend straight up to the RTH height and go directly to your return home point.   You DO have the ability to override the drone and cancel out of the failsafe mode unless the GEO system senses you are in a Prohibited flight area (per the manual).  I always think a moderately high point is better then a low one unless you are flying in low level terrain).  In all honesty,  if you did absolutely nothing at all,  your drone would have landed safely right next to you unless your drone was really really far away..  If you had all of your sensors on,  the drone would/should have avoided all obstacles in its way.  Again the exception would be if you are flying in a prohibited area.  In that case your drone will go straight down,  but I believe you have the ability to maintain your altitude until you find a safe place to land (I don't think you can ascend, only maintain altitude).  However your sensors (in theory) would be deactivated since the override priority would be to land.   Now this what I gather from reading the manual and the forum.  Maybe others can chime in.   However,  definitely don't buy another drone until you learn these things or you are just handing DJI money.  

what a nasty set of circumstances. sorry you lost it.

As many have now mentioned the CSC I wont repeat.
the RTH button can cancel the RTH

, many times many folks post and COMPLAIN about the CSC feature
they feel it has no use or value and should be removed.....
I don't agree though and in fact have used it in similar low level crash to save my motors.

this is a prime example of the value of CSC function

good luck!

Waht about using the PAUSE button?

24ctDrone Posted at 2017-2-9 16:39
dianea is exactly right.   This is an emergency protocol.  Very sorry to hear about your drone.  Worst feeling in the world.
Unfortunately it looks like you did everything wrong, and I don't mean to sound mean,  I hate when people get on here and say negative things.  I know you already feel like crap so I won't pile on.  First off,  YOU MAY BE ABLE TO FIND YOUR DRONE.  IF you still have your remote,  you can see the last place your drone was active through your user log.  Now if it truly is in a stream and somehow washed ashore while on,  go look for it!! It's worth a try.  The navigation system is really good!!
So here your mistake for next time.  If your drone was trying to Return Home and you pushed downwards,  instead of returning home it did exactly what you said.  Next time set your RTH to well above the highest point around you. If your failsafe comes on, do not panic!!!  Never panic and keep cool.  Most times when your failsafe comes you will be 100 % fine.   

Crikey, you really did not read the OP's report of what happened. It went into a river, over a waterfall and was lost. And there is no chance it would 'wash ashore while on'. Once it hits the water, especially over a waterfall, all systems will shut down.

dronist Posted at 2017-2-9 18:39
Waht about using the PAUSE button?

does the pause button stop the motors?

never heard of that!

Kirk2579 Posted at 2017-2-9 18:46
does the pause button stop the motors?

never heard of that!

The OP said:    "Instead, it dragged along the ground for a bit."

These things happen so fast in real time. Hindsight is in slow motion.

Terrible luck.

I've re-read this and think I understand.  Are you saying right when you were landing you didn't kill the bird quick enough?

My understanding of RTH is that you still have still control. So if the RTH did kick in, Let it do its thing and dont panick. Using stick control Bring  it back down And then hand catch / disarm.

I rather have it in the air than try fight with it too close to the ground

Really sorry to hear you lost it. expensive learning curve.

dronist Posted at 2017-2-9 20:15
The OP said:    "Instead, it dragged along the ground for a bit."

With the pause button it would have suspended the drone from dragging around and then he could have grabbed it from the legs.

only killing the motors would stop it from rolling about.

the pause button is to pause a "mission" in flight.
the motors and props with continue to run.

CSC is ONLY way to stop a runaway like he had

good luck and have fun flying!

Kirk,

You are right!.

I agree with the consensus that using CSC would have saved the aircraft. Depending on the battery level, hitting the RTH button while it's in RTH would cancel it and help regain control, but you would want to try and land immediately as soon as possible once you do that. I'm sorry for your loss.

Pay closer attention to battery level.  End of story.

The lesson here is that even if the aircraft is stopped on the ground it won't let you kill the rotors with left stick down in some circumstances.

Why such a condition is allowed is beyond my comprehension.

rgames Posted at 2017-2-12 08:49
The lesson here is that even if the aircraft is stopped on the ground it won't let you kill the rotors with left stick down in some circumstances.

Why such a condition is allowed is beyond my comprehension.

Because "Left stick down is not intended to stop motors"
Think decending fast from 400ft and keep left stick full down.... I don't believe that any one would want motors to stop in condition like that, as aircraft would fall like a rock to the ground.

If the craft senses that is dead still and the left stick is down THEN and only THEN it will kill motors.
In any other case we that motors can be stopped using the known combinations of sticks or left stick and rth button

Sorry for your loss.
A good reason to not go that low on your battery. I normally do not go much below 30%. It sounds like a rare set of circumstances where you hit 10% battery right as you landed, before you were able to kill the motors (it takes 3 seconds of sitting still to do that).  I have been landing before when 10% kicked in and it takes over to land automatically. Can cause you problems for sure.  Sounds also like you were not familiar enough with basic procedures (like CSC)  to be out flying in a more dangerous environment. Some more open field practice and manual reading/video watching would be in order.