uncommanded , unwanted rth and crash into stream

[Mazdaman323lx]

while flying in woodland , over a stream only 130 m from the home point my mavic air 2 hit 25% battery and did a automatic return to home.
It flew up into the trees and crashed down into the stream. There was no option to cancel the return to home. I got a low battery warning at 31% but because i walked with the drone while it was flying low and slow (I was inly 10m from it when it crashed) i ignored the warning. I know the drone doesnt know this and calculates the return journey to the home point including the ascent\desent , still RTH kicking in at 25% to cover 130m to the original home point seems off. I was able to fish the drone out of the stream /disassemble it and wash it out with ipa. After a good drying all seems ok with it bar the battery - jury still out on that. Aways just in case I'm missing something I attach the log if anyone wants to have a look and see did i miss something

 

[Meta4]

You set yourself up by starting with a battery that was already run down before you started, and then flying under tree cover.

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There was no option to cancel the return to home.

You didn't try flicking the flight mode switch out of P-GPS and back?

I got a low battery warning at 31% but ignored the warning.

No comment

 

[bobec231]

Sorry to hear about your crash
Check out drone-retriever. com they have some very good insight into water events, recovery and cleaning.
One point always bench test the drone with no props to make sure that all flight controls work after any negative event.

 

[Olav van Gerven]

RTH is triggered at 30% and you got the warning. Deciding to ignore a warning (which is your right ofcourse) might have consequences, in this case, RTH was triggered. That the drone then hit a tree, getting up to it's designated altitude for RTH, as you certainly checked before you took of, is also a consequence of your decision to ignore the warning.
In the end, let this be a lesson for you, an expensive one but that will make the lesson more valuable. A mistake you have made once but will make never again.

 

[Deleted member 114292]

while flying in woodland , over a stream only 130 m from the home point my mavic air 2 hit 25% battery and did a automatic return to home.
It flew up into the trees and crashed down into the stream. There was no option to cancel the return to home. I got a low battery warning at 31% but because i walked with the drone while it was flying low and slow (I was inly 10m from it when it crashed) i ignored the warning. I know the drone doesnt know this and calculates the return journey to the home point including the ascent\desent , still RTH kicking in at 25% to cover 130m to the original home point seems off. I was able to fish the drone out of the stream /disassemble it and wash it out with ipa. After a good drying all seems ok with it bar the battery - jury still out on that. Aways just in case I'm missing something I attach the log if anyone wants to have a look and see did i miss something

Well starting a flight with 40% battery is certainly Ill advised. I hope you’ve learned a lesson.

However I have to agree RTH At 25% would be unexpected.

 

[boblui]

...... There was no option to cancel the return to home....

I don't have the MA2 but according to the user manual, you can cancel RTH if the triggering reason is low battery ( but NOT critically low battery ). It can be done on my M2P



During RTH, obstacles at the front were detected and the craft tried to avoid them by flying backward. Unfortunately, it cannot sense obstacles above it and finally hit tree branches or something before it crashed.

 

[Mazdaman323lx]

I think after reading all your posts , what likely happened was , got the warning at 30% , ignored that as i had walked about 100m with the drone from the original home point , as I flew over the bridge and down over the stream I was flying the drone visually and never looked at the screen and missed the return to home countdown message. I only looked back at the screen when I saw the drone rise and had missed the chance to cancel then. Sound about right?

 

[Otisangb]

You didn't try flicking the flight mode switch out of P-GPS and back?

Didn't know this. I will put this in my toolbox when something goes wrong.

Maz, sounds about right to me and I am surprised it has not happened to me yet. Thanks for posting as this helps all of us out. Sorry about your crash though. When I crash (not if) I will post in this section to help other people out.

 

[boblui]

... missed the return to home countdown message. I only looked back at the screen when I saw the drone rise and had missed the chance to cancel then. Sound about right?

After RTH was started, the controller should have announced "going home" and beeped continously so you should have realized it immediately. Collision occurred after 18 seconds. There was sufficient time to cancel RTH.

 

[Deleted member 114292]

After RTH was started, the controller should have announced "going home" and beeped continously so you should have realized it immediately. Collision occurred after 18 seconds. There was sufficient time to cancel RTH.

As soon as I hit the first low battery mark my controller beeps continuously and nags me.

 

[boblui]

As soon as I hit the first low battery mark my controller beeps continuously and nags me.

That's why I set the low-battery threshold to the minimum value to avoid the annoying beeping. May be the OP has turned the volume of the phone down so the "going home" announcement was missed. I always make sure that the phone is at max vol before taking off so audio messages wont be missed. Those are usually important messages.

 

[Deleted member 114292]

That's why I set the low-battery threshold to the minimum value to avoid the annoying beeping. May be the OP has turned the volume of the phone down so the "going home" announcement was missed. I always make sure that the phone is at max vol before taking off so audio messages wont be missed. Those are usually important messages.

Interesting. I do exact opposite I set it higher because I’d rather be a little annoyed than crashed.

 

[Otisangb]

Interesting. I do exact opposite I set it higher because I’d rather be a little annoyed than crashed.

Got to agree with Done here. But then again I am kind of a worry wart about flying it because of the cost. It would be quite a financial hit for me to to not be annoyed by some beeping.

 

[boblui]

Interesting. I do exact opposite I set it higher because I’d rather be a little annoyed than crashed.

The problem is, the default setting is so conservative that the beeping started WAYYYYYYY too early. In the OP's case the drone was just 100 m from the home point and there was no wind but it decided to RTH when there was as much as 25% battery left. The MA2 consumes about 5% battery per km under no-wind condition so you can tell how much margin has been unnecessarily reserved.

Once you have learnt that, you will tend to ignore the low-battery warning just like what the OP has done. As the result, the beeping will become pure annoyance that serves no purpose. Worse still, if you become desensitised to warning signals including the critical ones, the chance of crash will actually be higher.

Knowing the power consumption of the drone, keeping monitoring the wind speed and direction during the flight and making an informed decision on when to return is my way of avoiding crash.

 

[Mazdaman323lx]

As soon as I hit the first low battery mark my controller beeps continuously and nags me.

As soon as I hit the first low battery mark my controller beeps continuously and nags me.

I honestly did not get that notification. I had 25% Battery and was standing 10m away (although) home point was 100m further back.

 

[Capt KO]

Thanks for all the lessons learned and passed on. You've saved someone else a lot of grief.

 

[Mazdaman323lx]

The problem is, the default setting is so conservative that the beeping started WAYYYYYYY too early. In the OP's case the drone was just 100 m from the home point and there was no wind but it decided to RTH when there was as much as 25% battery left. The MA2 consumes about 5% battery per km under no-wind condition so you can tell how much margin has been unnecessarily reserved.

Once you have learnt that, you will tend to ignore the low-battery warning just like what the OP has done. As the result, the beeping will become pure annoyance that serves no purpose. Worse still, if you become desensitised to warning signals including the critical ones, the chance of crash will actually be higher.

Knowing the power consumption of the drone, keeping monitoring the wind speed and direction during the flight and making an informed decision on when to return is my way of avoiding crash.

To add insult to injury I was only 20 feet away from the drone when RTH kicked in , hence my reasoning for ignoring the low battery warning. It only had to fly that far and was actually flying towards me when it happened. Hope this lesson will benefit someone else

 

[maelstrom]

To add insult to injury I was only 20 feet away from the drone when RTH kicked in , hence my reasoning for ignoring the low battery warning. It only had to fly that far and was actually flying towards me when it happened. Hope this lesson will benefit someone else

The problem is that the drone has no idea that you are not still at the original home point. Unless you update the home point to your new location, even if you are standing right next the the drone, it will still try to fly back to to its original point.

 

[Mazdaman323lx]

The problem is that the drone has no idea that you are not still at the original home point. Unless you update the home point to your new location, even if you are standing right next the the drone, it will still try to fly back to to its original point.

Yes , thats the lesson Ive learned the hard way. Still 25% battery to return 100m is a bit too cautious

 

[maelstrom]

Yes , thats the lesson Ive learned the hard way. Still 25% battery to return 100m is a bit too cautious

You need to bear in mind that running the batteries too low can shorten their lifespan and even cause permanent damage. There are plenty of references about that say you should avoid discharging Li-ion batteries below 20% capacity, particularly if the discharge current is high (flying against the wind during RTH, for example). See: How to extend the life of your lithium-ion batteries