M2Z didn't have enough battery to RTH

[emufriedchicken]

As the title says. My M2Z did a low battery RTH this morning and for some reason it came up 700 meters short of home and did a auto land. Managed to steer it to a place that I could drive close enough to retrieve it. This is the 1st time it has ever done this. Every other time it still has more than 10-15% battery still when it lands. Am running latest firmware and the latest version of Go4 on my ipad mini2. I have even flown in strong winds and it still makes it back home into the headwind with plenty of power left . Lucky I dodged a bullet today with a successful retrieve but still scary of what might have been. Any ideas of what did happen or maybe a setting or 2 that I can tweak or maybe this is a common issue that has a fix that I haven't heard about yet. thanks in advance everyone ..fingers crossed there is a fix!

 

[Former Member]

I always plan to land with 30% battery.

 

[Meta4]

As the title says. My M2Z did a low battery RTH this morning and for some reason it came up 700 meters short of home and did a auto land. Managed to steer it to a place that I could drive close enough to retrieve it. This is the 1st time it has ever done this. Every other time it still has more than 10-15% battery still when it lands. Am running latest firmware and the latest version of Go4 on my ipad mini2. I have even flown in strong winds and it still makes it back home into the headwind with plenty of power left . Lucky I dodged a bullet today with a successful retrieve but still scary of what might have been. Any ideas of what did happen or maybe a setting or 2 that I can tweak or maybe this is a common issue that has a fix that I haven't heard about yet. thanks in advance everyone ..fingers crossed there is a fix!

Post flight data if you want analysis to make sense of this.
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
Come back and post a link to the report it gives you.

 

[emufriedchicken]

Post flight data if you want analysis to make sense of this.
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
Come back and post a link to the report it gives you.

Here is the link to the report

DJI Flight Log Viewer - PhantomHelp.com

 

[devisger]

Looks like you were fighting a serious head wind all the way back. The experts will have a more detailed break down.

 

[Meta4]

Here is the link to the report

Your flight distance to home would have only been 6 km which should be easy.

I'd be doing quite well if I got $5 for every flyer that goes too high and pays no attention to the wind.
You flew at 670 feet where the wind is always going to be much higher than down on the ground.
At 4:20 you made an easy 14 metres/sec with obstacle avoidance enabled.
That tells me there was a good tailwind at that point.
Around 5:20 you took it up to 670 ft and kept powering away further downwind.
Now if you zip away with a raging tailwind, how do you think the return trip is going to go?
<<Hint>> You're going to have to turn around well before 50% if you want to get home
<<Hint>> You should get down out of that wind if you want to see the drone again

Around 7:27 at the turn, things slow down so you switch to (battery burning) Sport Mode.
You seem to have trouble steering straight and wiggle all over the sky while your battery goes from 50% to 40%.
You give up on Sport Mode at 8:20 and continue wandering, switching to RTH after a while at 9:38.
You've been making 1.8 metres/sec in P-GPS and the drone is still up 538 ft.
You bring the drone down to 260 ft and the speed picks up to 4-5 m/s
At 13:23, battery at 9% and 730 metres from home, the drone gives up and autolands before it runs empty and falls.

Any ideas of what did happen or maybe a setting or 2 that I can tweak or maybe this is a common issue that has a fix that I haven't heard about yet. thanks in advance everyone ..fingers crossed there is a fix!

Yes, it's a common issue.
What you have to tweak is your awareness of wind speed and direction and think what it will mean to the drone, especially the return trip.

 

[zocalo]

Meta4 beat me to it - judging by the relative speeds of outbound vs. inbound you had a tailwind on the way out and a headwind on the way back. You've also got a lot of variation on your flight speed on the way back, likely indicating gusts rather than a steady breeze so the drone will be working harder to stabilise itself - especially around the high-wind velocity warnings at 11m09s and 13m45s (when it was already in the process of landing).

Comparing outbound cruise speed with inbound will give you a pretty good idea of the conditions - if the latter is significantly lower then you need to think about conserving power because you are fighting the wind. Some things to do:

Reduce altitude - wind speed generally drops as you descend.
Switch to regular flight mode - sport mode is more power hungry and in tripod mode you'll crawl along which is even worse.
Stop taking pictures/video, or panning the camera around for that matter - this will also save power for getting home.
Start thinking about places where you can land safely for later retrieval.

 

[sar104]

Wind speed was the problem, as mentioned above. 40 mph in the wrong direction above 150 ft where you were flying.



You need to rethink your strategy - your statement "I have even flown in strong winds and it still makes it back home into the headwind with plenty of power left" suggests that you don't understand the airspeed limitations of these aircraft at all. Have you been assuming that they can fly in any wind conditions?

 

[PhantomFandom]

Wonderful analysis by the guys above. Wind speed must always be a very serious consideration in any flight. Not just on the ground, but at whatever altitude you plan on flying. Use UAV Forecast at your location to get an idea of what the sustained wind and gusts are at altitude. Always try to fly upwind first!

To address a couple of the questions/remarks of the OP:
No there is no "fix" for this "issue" because this is no issue with the craft. This was 100% operator error. You must be more aware of the flight conditions and limitations of your craft.

You mentioned that in the past the Battery Low RTH worked fine. That is an emergency fail-safe mechanism and it should not be used as your primary method of determining when to start heading home. First issue with that approach, you saw yourself and next time it could be worse. Second issue is that you are therefore constantly bringing your battery levels down to almost fully depleted, and that is not good for battery life. Personally, I always try to be back at home point and on the ground with 30% battery remaining.

Very glad you got your Mavic back intact without any damage. This was a good learning experience.

 

[emufriedchicken]

Thanks for the awesome post mortem on my flight everyone.

This area I live in always has high sustainable winds this time of the year and only get to fly when it dies down to say breezy conditions or if I am really lucky they might drop off all together for a couple of days then roar back in again and ground me. The winds that day were by no means the strongest that I have been caught out mid-flight and flown in . I always thought the drone kept recomputing the wind speed and distance from home to allow for the maximum distance and make an earlier than usual RTH should conditions arise. But as mentioned before I think the real killer yesterday was that the wind was gusting which probably would have been impossible to calculate anyway a accurate RTH.

I have now learnt 1st hand the limits of this aircraft and my failure as an operator of not reading the wind right and taking the necessary action to remedy the situation. I was extremely lucky that I was able to guide down to a safe landing place under auto land for a safe retrieval. It could have been a lot worse and had total loss of aircraft. I have taken all suggestions on board that were given and will be more aware of wind conditions . Thanks everyone for your help it much appreciated and if you have anything to add please feel free to.!

 

[JDawg]

Lucky you got it back. I have been on this forum for under a year and it seems that the last 6-8 weeks I have read about more lost drones from wind than all the previous months combined.

 

[Meta4]

I always thought the drone kept recomputing the wind speed and distance from home to allow for the maximum distance and make an earlier than usual RTH should conditions arise.

As demonstrated by the flight data, it doesn't.

But as mentioned before I think the real killer yesterday was that the wind was gusting which probably would have been impossible to calculate anyway a accurate RTH.

It looks like gusting wasn't a real issue. In RTH from 40% - 30% where you were at a constant altitude and straight-line course, the speed was quite steady and only changed significantly as you descended later.
By contrast, the speed was up and down from 50%-40% where you had trouble steering straight as shown by this detail from your track.
Flying at different angles to the wind caused the variation in speed.

 

[emufriedchicken]

As demonstrated by the flight data, it doesn't.


It looks like gusting wasn't a real issue. In RTH from 40% - 30% where you were at a constant altitude and straight-line course, the speed was quite steady and only changed significantly as you descended later.
By contrast, the speed was up and down from 50%-40% where you had trouble steering straight as shown by this detail from your track.
Flying at different angles to the wind caused the variation in speed.

I can only assume that the path shown above of my M2Z must be as a result of the wind of some sort as I don't think I have ever flown that erratically since my early days of flying the cheap $20 drones. Definatelty wasn't from any input from the controller . Also looking at the other map trajectory when it did go to RTH it was off course anyway so the winds must have been way too strong at that altitude to make it home. But as said before the ultimate decision was mine to fly and I made a mistake and shouldn't have flown and didn't read the wind correctly

 

[Meta4]

I can only assume that the path shown above of my M2Z must be as a result of the wind of some sort as I don't think I have ever flown that erratically since my early days of flying the cheap $20 drones. Definatelty wasn't from any input from the controller . Also looking at the other map trajectory when it did go to RTH it was off course anyway so the winds must have been way too strong at that altitude to make it home.

Recorded flight data is interesting in that it doesn't always tell the same story as the memory.
Your flight data shows that from 50%-40% you had the right stick full forward but you also pushed the right stick left and right several times corresponding perfectly to the wiggling flight path.
On RTH the drone was facing 41 degrees which would have brought it home in less windy conditions.
It appears that it was pushed to the north by the wind.

 

[lolo780]

Hold the left stick up to counter auto landing and fly it back home. Even on 0% the M2 can go another 1000m. In calm conditions I've gone 3km from 10% battery.

As others mentioned, get as low down as possible when returning into a headwind.

 

[emufriedchicken]

I have heard that Carbon Fibre Props are better in wind than the standard props because they don't flex as much. I realise that it isn't going to be the magic bullet to solve my problem as it was operator error but it might make my flights more stable and able to utilize the battery power more efficiently...Thoughts?

 

[Meta4]

I have heard that Carbon Fibre Props are better in wind than the standard props because they don't flex as much. I realise that it isn't going to be the magic bullet to solve my problem as it was operator error but it might make my flights more stable and able to utilize the battery power more efficiently...Thoughts?

Stability wasn't the problem.
Being >600 feet up in a wind that was too strong for your drone was the problem.
It wouldn't matter what props you were swinging in that wind.
If the wind was stronger you would have ended up getting blown backwards like this flight also from yesterday: Mavic Pro Failing to RTH

Strong winds are a serious issue, involved in the loss of plenty of drones.
You need to be aware that winds get stronger higher up and flying downwind in a very strong wind can be a one-way flight.
Before you launch consider the wind you;ll have for the return trip.
It's much better to have a slow flight out into a strong headwind and an easy flight home.
Infinitely better than doing it the other way around.

 

[emufriedchicken]

Stability wasn't the problem.
Being >600 feet up in a wind that was too strong for your drone was the problem.
It wouldn't matter what props you were swinging in that wind.
If the wind was stronger you would have ended up getting blown backwards like this flight also from yesterday: Mavic Pro Failing to RTH

Strong winds are a serious issue, involved in the loss of plenty of drones.
You need to be aware that winds get stronger higher up and flying downwind in a very strong wind can be a one-way flight.
Before you launch consider the wind you;ll have for the return trip.
It's much better to have a slow flight out into a strong headwind and an easy flight home.
Infinitely better than doing it the other way around.

I agree 100% with your diagnosis of my flight and I do realise that CF props wouldn't have made any difference at all with the outcome.

However I do live in a well known Windy part of our country and do my best to fly early morning or on days when there is gentle breeze at its best. Would CF props allow me to utilize the battery power a lot better in these conditions ???

your recommendations of launch, direction of travel with wind is all taken on board and will definitely be used! Thank You.

Just to give you some idea of the winds we get where I live here is a link to what the wind does to trees here. Leaning Trees » Visit Geraldton And no I wouldn't even look at my drone case when these winds are howling through which this time of the year can be very frequent sometimes!

 

[ottodawg]

Hold the left stick up to counter auto landing and fly it back home. Even on 0% the M2 can go another 1000m. In calm conditions I've gone 3km from 10% battery.

As others mentioned, get as low down as possible when returning into a headwind.

Great advice, had to do this today when I got caught out in a headwind. Had to hold the left stick up. Made it back to the home point with 0% battery, 3.5 v if I recall correctly.

 

[ehenderson410]

I only had to lose 1 spark to learn how to keep tabs on the wind. That was when they first came out too, so it was a pricey little lesson.