I lost air 2s at sea... after 12% battery drone was not responsive.

[Meta4]

Here's my assessment of the whole flight.

Flying over the sea (where there are no obstacles) with RTH height set at 175 metres
Two minutes into the flight, at 130 metres, you are only able to fly at 9.6 metres/sec with full right stick.
As the still air top speed is 15 m/s, that should have been a warning about wind speed.

At 4:40, you were higher at 152m and could only make 7.5 metres at full stick.

At 6:50.9 you reached your target, 2.7 km from home and the battery is down to 38%.
You initiate RTH which takes the drone up to 130 metres (where the wind speed is higher) but there is a tailwind for the return trip.
Drone comes home at 12 m/s, arriving at 11:00.
Battery is now at 18%, drone is now 173 metres high.

Because you have no idea of the importance of a safety margin when flying at sea and are completely oblibious to the wind speed and direction, you decide to keep flying.
You start a flying west (which means your return will be against a headwind - but you don't care)

At 12:00, battery has reached 14%, the drone is 491 metres from home, 55 metres high and you turn back toward home.
At full stick, the drone makes 3.2 m/s towards home so you go to (battery burning) Sport Mode and speed increases to 5.5-8 m/s fighting against the gusty wind.

After only 7 seconds the battery is down to 11% and critical low voltage.
It starts to autodescend.
The drone is still 393 metres from shore and 58 metres up (you don't show any understanding of the way the wind is stronger at higher altitudes).

Fighting against the autolanding with full left stick and using full right stick to head toward land, you get within 156 metres of land at 13:10 & 6%.
The speed has been 1-2 m/s.

But at 13:10, with the battery getting weaker, the drone starts going backwards at 4.9 m/s, despite full right stick.

At 14:26.4 the battery hits 0% with the drone now 350 metres out and being blown further away.

The sorry story ends with the drone 700 metres out and sinking at 16:55.5.

 

[tascagdas]

Here's my assessment of the whole flight.
...

Thanks for your reply.

Mistakes were made. No one is harmed only my wallet.

 

[slup]

...You can clearly see drone is drifting and cant resist to wind. And you can see waves to understand wind speed and direction. Wind was not 12.9 m/s it was like 8-10 m/s

I don't really understand what you're trying to achieve with all your arguing ... you messed thing's up, nothing odd or unexpected was going on during this flight. Flying drones for 4 years isn't a guarantee when it comes to knowledge which you proved without a doubt.

When we discuss winds we don't look at waves on ground level ... what's interesting is the winds where the AC is. So if the average winds I showed you earlier during your flight wasn't enough to convince you that the wind was stronger than you thought ... here below you have all wind speeds that your AC faced during the whole flight, they are calculated on the basis on the AC attitude together with the drag coefficient for a Mavic Air 2s.

(Click on the map to read out the letter markings for all instances of wind calculations to find it in the chart further below)





And as said before ... with that low battery percentage left, with an ongoing forced low battery auto landing your MA2s was totally powerless & hadn't a chance to make progress towards headwinds stronger than what's specified for a MA2s, which is:

 

[RUFFSTUFF]

Please, don't treat me like i'm unconscious idiot.​

No one is doubting your consciousness, sir. Don't be mad at us.

 

[umanbean]

Flying drones for 4 years isn't a guarantee when it comes to knowledge which you proved without a doubt.

Thanks, I was thinking the same thing when he said that... but it sounds much more plausible coming from you

When we discuss winds we don't look at waves on ground level ... what's interesting is the winds where the AC is.

'They Call the Wind Mariah'

 

[spudster]

Thanks for your reply.

Mistakes were made. No one is harmed only my wallet.

You need to understand the discharge curve of LiPo batteries. From 20% down to 0% the voltage drops very quickly, less voltage means less power. It is how all LiPo batteries operate. See attached graph, view the lowest curve as that is the higher 2C discharge rate.

 

[RUFFSTUFF]

 

[Phantomrain.org]

Yes , even for seasoned Pilots ,12 % battery over the Open Sea is just a recipe for a forced landing. One thing that we stress is that the Wind is much stronger than what you are registering from your take off point. Honestly this can happen to anyone.

Flying over the water is tricky

Phantomrain.org
Gear to fly in the Rain and Land on the Water.

 

[Jamesz]

As the others have said, much to learn from this. As a new pilot, flying way beyond VLOS and too high to be safe, in stronger winds and down to low battery shows a need to rethink how you operate your drone in order to remain safe and not lose another.

 

[Mikieh]

I'm sorry for what happened, but personally I prefer to get back to the take-off point with 30% / 35% battery left and land.
LiPos should not be discharged to less than 2.7 Volts / cell. (3 cells = 8.1 Volts) better not to go below 3.0 volts and they cannot withstand temperatures above 60 ° C.
Unfortunately the battery has abandoned you.

I agree about the 30% fly back rule. No telling what you’ll run into on the way back, especially with my Inspire 1, but I do it with my Mavics as well(I own both pro and zoom).
When I get all the way back will hover to about 20% then shut it down.

 

[Deleted member 154384]

I agree about the 30% fly back rule. No telling what you’ll run into on the way back, especially with my Inspire 1, but I do it with my Mavics as well(I own both pro and zoom).
When I get all the way back will hover to about 20% then shut it down.

Let's say I always try to fly not too far from me ... respecting the laws

I agree about the 30% fly back rule. No telling what you’ll run into on the way back, especially with my Inspire 1, but I do it with my Mavics as well(I own both pro and zoom).
When I get all the way back will hover to about 20% then shut it down.

Let's say that I always try not to fly too far distances and in compliance with the laws.

 

[PompousWindbag]

I just love this site. Not when pilots lose their drones :-(
But for the in depth data that comes from these incidents by the guys on here who have vast knowledge and input. It’s reassuring to know that for almost all of these sad incidents its almost always operator error. Fingers crossed when I get into trouble I will remember what to do and not panic! Thanks to the “gurus”

I was just thinking the same thing.

 

[RUFFSTUFF]

 

[Mikieh]

I was just thinking the same thing.

There is nothing worse than seeing your drone go down never to be found. It burns rules into your head!

 

[mmoguls]

What have you learned from this experience?
In my opinion there's only one place a drone with 12% remaining battery belongs: on the ground directly in front of you, waiting for a battery change

 

[Biggie777]

Ah man,sorry for your loss. I been thinking a lot about the 2S and how bad I want one and can't make up my mind and you just lost it.. sorry man,not a cheap loss either.

 

[Dawnvt]

I find it sad when someone loses their drone. I learn a lot from these posts. I want to fly my MA2 again, so I keep it close and watch the battery and land to switch batteries (I have 3 of them). VLOS & RTH are my friends.

 

[DavidBlezard]

I fly over water about 98% of my flights. Battery level and altitude are crucial to a successful flight. Sorry for your loss.

 

[fuzzball]

In the DJI GO 4 app you can display the battery status on the main page. Then it's a single click shortcut to view battery status including the volatage of the individual cells. I check that once or twice every flight. Keeps me situationally aware of not only battery status but also the status of each cell. One cell depleting quicker than others and it's an immediate landing for me. So far all my original batteries are holding up nicely with balanced cells. The little battery icon shortcut on the main page is a must for me now. At 25-30 percent it's heading back to land.

 

[Jason_M]

Interesting reading.....As said by many here. Try and land with about 30% +/- left in Battery. Not only good for Battery Health but mental health. The reason for that little reserve is you don't want to come back and you're trying to land, and you've got people out walking with Dogs chasing seagulls around you.