Looking for advice

Jim abbatoy · Feb 19, 2017

I crashed my P3P today. Was flying a 17 minute waypoint mission in Litchi with full battery. All was well until battery life dropped fairly quick and the bird initiated RTH as it should. My guess is some random wind gusts may have ate up the battery.

When the bird was within 400 feet of home, it started to land. I switched to P mode, cancelled RTH and raised altitude to bring it home.

My problem is I got severely disoriented as to the direction of the bird. I had visual for a short time, but lost it as it got further away. RTH took back over and the bird landed about a block away in a tree. Good news is I only damaged the ribbon cable. Thanks to amazon sending me the wrong one for my P3S a while back I had an extra.

My question is, how would you reorient yourself? Any words of wisdom from someone more experienced than me? The sun was making it near impossible to see my tablet screen.

BTW find my drone is awesome. I only had around 7% battery left when I located the bird.

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msinger · Feb 19, 2017

The next time you get disoriented, use the radar in DJI GO to steer your Phantom back toward the home point. Simply yaw until the red aircraft symbol is pointed toward the center of the radar and fly in that direction until your Phantom is in sight.

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Jim abbatoy · Feb 19, 2017

Yep I know about the radar. Unfortunately, the bird was landing when it was about 400+ feet from home. I think I panicked and tried to visually get it back. But I was in Litchi and didn't think fast enough to switch to DJI go.

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Roamer105 · Feb 19, 2017

I am not sure you could have done anything different because the bird appeared to execute the emergency landing due to critically low battery level, if it had a little more battery, it would have come home as expected. Once it is in critical mode, you loose control. You may lower the critical battery level percentage to something closer to 0 and cross fingers that it will not drop out of the sky due to shut-down.

Jim abbatoy · Feb 19, 2017

Thanks. It dropped from 36% to around 15% in a very short time. I just looked and I had critical set at 15% which probably caused the problem. Maybe I'll lower it to 5-10%. I never fly past 30% as a rule. Only other thing I can think of is flylitchi underestimated the time of the mission. Normally it overestimates though.

I've flown a ton of 17-19 minute missions and had 30+% battery remaining. Hmm. I'm at a loss. Well at least it was an easy fix. Well once I changed my underwear. Haha. It was a ***** getting it out of the tree though. It landed right in a V in the branches.

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DanMan32 · Feb 19, 2017

This answers the question in another thread on what Litchi will do on missions if battery gets low. Most assumed critical low battery landing would occur but this shows smart RTH also applies.
On reaching critical low battery setting, it will land and not go home, though you can control movement including countering descent to some degree.
Does litchi show the 'wand' in a map view like Go? That could have helped you orient.

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Jim abbatoy · Feb 19, 2017

That would have helped immensely. Due to a large amount of trees, my RTH altitude is set to 250 feet. At that height and distance it's very hard to get oriented. Especially under the stress of an unexpected critical battery situation. I'm going to spend a lot of time manual flying to improve my manual flying skills as a result of today's extravaganza.

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Loz · Feb 19, 2017

Jim easy to say but not to panic is #1 advice as you appear to know. Disorientation (AC flight direction) is not uncommon, particularly when AC further away from Pilot.

What I do is hover, then fly left, then right (on sticks) - if visual confirmation watching AC movement I s the same, then I know I'm facing away from home, if reversed, I'm facing towards home.

If necessary rotate aircraft 90 on sticks and repeat - if you practice this a few times (nearby first so you can see easily what's happening) it's not too difficult to rapidly determine orientation and then head home. Hope this made sense and helps

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Meta4 · Feb 19, 2017

Jim abbatoy said:
Yep I know about the radar. ... But I was in Litchi and didn't think fast enough to switch to DJI go.

Litchi has a radar display as well, no need to swap apps.

dannyz · Feb 20, 2017

msinger said:
The next time you get disoriented, use the radar in DJI GO to steer your Phantom back toward the home point. Simply yaw until the red aircraft symbol is pointed toward the center of the radar and fly in that direction until your Phantom is in sight.

View attachment 76644

I find quite often, I launch my drone, the radar is working fine, then, at some point in the flight, the direction goes out of whack by 180 degrees, and if I use radar to fly, the AC goes the opposite direction to where it shows it is pointed. This seems to happen more often when I am quite far away, usually just far enough that I look away for a second, then can't find it, start flying by radar to bring it back, and more often than not, the distance numbers get larger as I fly it toward me. When I finally get it back, it has somehow switched compass direction by 180 degrees.

It did this on 2.91, 3.01, and 3.12, (but not always) byt I havn't noticed it yet on 3.13.

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Meta4 · Feb 20, 2017

dannyz said:
I find quite often, I launch my drone, the radar is working fine, then, at some point in the flight, the direction goes out of whack by 180 degrees, and if I use radar to fly, the AC goes the opposite direction to where it shows it is pointed. This seems to happen more often when I am quite far away, usually just far enough that I look away for a second, then can't find it, start flying by radar to bring it back, and more often than not, the distance numbers get larger as I fly it toward me. When I finally get it back, it has somehow switched compass direction by 180 degrees.

The compass in your tablet (not the Phantom) needs to be calibrated.
But regardless of a badly calibrated tablet compass, you can still use the radar display.
You are in the centre - fly the red paper plane toward the centre.

dannyz · Feb 20, 2017

Meta4 said:
The compass in your tablet (not the Phantom) needs to be calibrated.
But regardless of a badly calibrated tablet compass, you can still use the radar display.
You are in the centre - fly the red paper plane toward the centre.

I have used 3 different tablets, all have done it, but, you misunderstand. When I point the arrow at the home position, the craft flies away from me! (It starts out at the beginning of the flight moving correctly, but part way through the flight it switches 180 degrees)

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tcope · Feb 20, 2017

A good rule of thumb is to be at your home point at 30%, not returning home. I'd also recommend that you turn on the voltage display and watch that as much as the percentage. The percentage is a guess by the software on the amount of battery left. You should be landing the Phantom _before_ 3.4v and not allow it to drop below 3.3v. At 3 volts the battery will shut off.

Jim abbatoy · Feb 20, 2017

With the exception of yesterday I'm always on the ground by 35-40%. I think there may have been some random gusts that ate the battery up. I was at 48% at around 700 feet from home. The battery percent plummeted at that point. I'll be keeping a real close eye on that battery from this point on. AUV forecast had the wind at 12mph @250 feet when I started the mission. By the time I recovered the bird from the tree the wind had increased to 18mph.

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Jim abbatoy · Feb 20, 2017

After a couple hours of self review and watching the video, here's what I've learned. The bird must have experiences a couple gusts causing it to work extra hard and draining the battery faster than usual.

Once the bird was in sight and started to land, I should have initiated home lock and tried to increase altitude rather than waste time trying to get oriented. At the point it started to land I clearly had no time to waste. Home lock seems to be the quickest way to save the bird in this circumstance.

Considering I never fly below 30% battery,I think I should set the battery warning at 30% and reduce the critical warning to 5%. This should have given me plenty of time to get home before a forced landing.

Anyone have differing thoughts? I'm open to suggestions.

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Loz · Feb 21, 2017

As you asked, I think critical warning at 5% is too low and leaves pretty much no room for error - I'd keep it at 10%. It's meant to enable your phantom to save itself by landing before battery dies - why would one limit this capability? One cannot typically know in advance that 5% will be enough. I fly 30 and 10% settings.

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DanMan32 · Feb 21, 2017

On the go app you can't go lower than 10 for critical.
It doesn't make sense that the actual heading is 180 degrees than what the radar shows. However when you are real close, the little red triangle is right on top of center so you can't really tell. That's when the map view becomes handy, especially with that line between home point and AC.
Note too that it's the red triangle you are interested in, not the green. The idea of the green is the camera angle which can be changed on the inspire to be different than AC heading. Think of the green as the AC's headlight shining out.

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DanMan32 · Feb 21, 2017

Here's the link to the video about the attitude indicators and map view in the GO app:
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Jim abbatoy · Feb 22, 2017

Loz said:
As you asked, I think critical warning at 5% is too low and leaves pretty much no room for error - I'd keep it at 10%. It's meant to enable your phantom to save itself by landing before battery dies - why would one limit this capability? One cannot typically know in advance that 5% will be enough. I fly 30 and 10% settings.

- Phantom P3A & P3P -
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Very good point. I think I'll follow your advice and leave it at 30/10. Now that I've discovered the virtue of home lock, I'm confident I could have got the bird home given my degree of disorientation. I've been flying for over a year now, and this is the first time I've had a forced landing due to battery voltage and I panicked when I couldn't orient myself. After reviewing the video and healthy drone, I'm convinced a strong, in forecasted headwind caused the battery to drain so quickly. Live and learn.

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Jim abbatoy · Feb 23, 2017

I think I figured out what happened. Any input would be appreciated.

I flew the exact mission yesterday. The bird was to takeoff from my yard and proceed at 20mph to the lake. Slow to 7 mph and fly the shoreline then raise to 200 feet and travel the shoreline at 15 mph back to home point.

What I noticed yesterday is the bird never increased to 15 mph as the waypoint was supposed to. It climbed altitude, but continued on at 7mph which obviously would increase battery consumption for the longer return time.
I rechecked mission hub and all the settings were correct so I deleted the mission as there was an obvious problem with it.

Learning point - had I monitored my speed more closely, like yesterday I could have manually throttled up and got back before critical battery kicked in.

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