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Object avoidance saved my *** (lessons learned)

plexus

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Hi. New MA pilot here. Some 10 years experience flying RC helicopters and dumb drones. After pracicing with the MA for a couple weeks, I went on a back country canoe trip with the intent to document it with the MA. I knew I was too green to do so because I haven't fully explored all the ins and out of the MA and its associted software control. Sure enough on one flight I almost lost it. Here are my lessons-learned. These apply to new MA pilots mostly:

1. Keep the RTH battery limit to 20%. I set it on 10% because I was too cocky. This didn't leave me enough time to fully manage the MA back.

2. Learn the audio cues from GO 4 and look at the screen when you hear key cues. Resist the urge to keep your eye on the MA. Not being comfortable with the MA I kept my eye on it and totally didn't pay attention to the audio cues. This resulted in the MA going into RA as the battery depleted. RTH was very precarious where I was.

3. Ensure your RTH spot is not obstructed by objects creating a ceiling. I launched off the ground but under tree cover. so when RTH initiated it was above the trees and couldn't land.

4. Leave obstruction avoidance on. I did. and it saved my ***.

5. Don't fly with a low battery trying to use up the remaining juice unless you are in a clear spot. I did and there was a screw up and I almost didn't have the power I needed to get the MA back.

6. Learn to fly nose-in. I am only ok with nose-in flight. In this emergency I didn't feel comfortable with nose in so I wasted 3 seconds with a yaw maneuver to go tail-in. This wasted valuable time.


Here's what happened. I will post a video of it with the ATC audio intact so you can hear me panic:

I was at a camp site on a lake. I had about 3:30 on the battery from a previous flight. Since there is no way to charge batteries in the field, I wanted to use as much of each battery as possible. I decided to fly the MA for a quick pan across the camp site, from over the lake. I was nose-in for this. I am not as good at nose-in as I am tail-in. The pan shot went well but as soon as I was done, and the MA was pointed at me, it went into RTH because the battery was low.

At this point I began to panic and kept my eyes on the MA and totally tuned out GO 4. I missed the 10 second window to cancel RTH because I totally forgot the process because I was trying frantically to get the MA back to me. Going into RTH was pointless because of the geography and wasted more precious flight time. Remember I set the warning to 10% giving me only 2 mins before emergency RTH.

I launched from the ground on shore but there was tree cover above the RTH point. The MA started to ascend to an RTH alt of 30m. I was VERY LUCKY that it was still out a bit from the trees enough that the object avoidance could pick up branches just above it because of the field of flew of the front sensors. This worked amazing - the MA stopped very close to the branches and moved itself back to clear them, then continued to ascend.

It reached RTH ALT and then moved forward to the RTH height. But now it wa over the trees. It wouldn't descent because of the bottom sensors. Thank you!!! At this point I regained control and moved the MA back out from the trees and quickly descended narrowly missing branches. I have a good eye for this kind of thing from my RC experience.

From there the MA was almost in front of me but I didn't want to risk nose-in so i used yaw to go tail-in. Drove the MA back right to me and landed in my hand. As it was landing it went into emergency RTH mode for the last second of landing because I grabbed it.

Whew. Luck man. and obstacle avoidance - wow. it worked great and saved my MA from my stupidity.

The video starts out with me positioning the MA for a pan across the campsite. I then spin it around for a shot of the other side wanting to do a similar shot. I realized I didn't have the campsite across the lake in the shot so I am sizing that up. I should have pre-established what shots I wanted. Then I begin to bring it back nose-in and goes into RTH because I didn't hear the warning and didn't disengage. the ascent up and until it goes nose-out, its RTH. All the motions on the ascent are becase of obstacle avoidance moving the MA safly away from the trees. I lost control and I am panicing. It flies over the trees at the RTH location. the obstacle avoidance prevents it from going down. I get control back and bring it down manually after positioning it nose-out. I narrowly avoid trees on the way down. Just I grab it, emergency RTH goes on (fast warning beep). Eeeesh!

 
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Lake_Flyer

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All good observations.
Your RC flying experience pays off.
I would say, never rely on RTH or obstacle avoidance. Be glad if/that it does what it is supposed to do in an emergency. But it is always better to be able to trust your own flying skills and judgement.
 

MrRobville

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Thanks for sharing your experience. I guess this all boils down to one tip: Take your time. Always.
A rushed preparation (not checked RTH height, no fully charged batteries, not checking the takeoff area) is bound to have complications. Good thing is, you only have to experience this once in order to avoid it next time. I can tell personally. ;)
I'd recommend making a pre-flight checklist (there are a few around here as well) and taking it with you so you can quietly run down each and every item until you are confident to takeoff. Not only does it avoid unnecessary risks, it also makes your flight a lot more comfortable, knowing that you've taken care of everything.
Flying a $1000,- quad can be tense, so make sure to make it as easy and comfortable for yourself as possible.

Also, should you ever be with other people who are in a rush while you want to take the shot, either ignore them or don't takeoff at all. Whatever you do, never rush your flight, and try to avoid a panic if things go wrong.
 

RayOZ

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Running batteries and storing below 20% is not good for the batteries. Reduce the battery life.
 

plexus

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Running batteries and storing below 20% is not good for the batteries. Reduce the battery life.
The battery was not stored at 20%. It was used 2 hours before this flight.
 

kidroc

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You can stop RTH to home at anytime using the pause button or just hit the RTH button on the RC.
 

charlas

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Or flicking it into sports mode, kills off all the intelligent flight modes, a life saver at times :)
 

plexus

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Or flicking it into sports mode, kills off all the intelligent flight modes, a life saver at times :)
In my head, I knew this. But I never tried it. I never got into a "situation" before so I didn't want to go trying things I didn't have direct experience with. I made this decision ont he fly (pun intended). I think it would be a good idea for me to try and simulate emergency situtions and practice with getting the workflow down 2nd nature. I knew time was of the essence and so I didn't want to waste time with things I haven't tried and are comfortable with knowing what they do. As it was if I was messed around with something that didn't do what I expected the MA may have emergency RTH'ed into the canopy.

I am going to work out some mock emergency situations and get some experience with these controls first hand.
 

colinfowler

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In my head, I knew this. But I never tried it. I never got into a "situation" before so I didn't want to go trying things I didn't have direct experience with. I made this decision ont he fly (pun intended). I think it would be a good idea for me to try and simulate emergency situtions and practice with getting the workflow down 2nd nature. I knew time was of the essence and so I didn't want to waste time with things I haven't tried and are comfortable with knowing what they do. As it was if I was messed around with something that didn't do what I expected the MA may have emergency RTH'ed into the canopy.

I am going to work out some mock emergency situations and get some experience with these controls first hand.
Hit RTH then switch to sport and fly back and land manually.
Hit RTH then press RTH on RC as you would need to if you suddenly had no screen, then fly back and land manually.
Don't land too close to yourself as OA will kick in.
 

Mossiback

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Also set RTH to hover if there is something over your home point.
 
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plexus

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I think the key thing here is before taking off assess the landing situation and if the automated RTH maneuvre wont work because of obstructions, set it to hover. If its ok then set the RTH altitude to an approriate height. Also listne for the RTH warning and be ready to his pause if you need to regain control.

Of course, you all know this. I "knew" it but never practised it and in the heat of the moment I was not able to recall all of this. I think it would be good for me to do some practise sessions to drill this into my brain, even if they are hypothetical.
 
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