First Crash

[TDZHDTV]

I’ve got to say I find the AC interrogation you guys do a fantastic insight into what to do and what not to do when flying. Thankfully my only serious crash with my MA didn’t need any investigation as it was pure pilot error (panicked when a marauding flock of angry seagulls took an unhealthy interest in my drone, resulting into my panic flying in sports mode into the side of a derelict building, but that’s another story that didn’t end there!). Keep up the great work ?

 

[ajkm]

your analysis of the log states several times the drone was not responding to the sticks

No, the analysis several times says “without any input from the sticks” or words to that effect. That is completely different.

 

[paulatkin73]

The drone was also descending without any stick input and no message to explain why.
No other DJI drones do that so I'm not sure why it did but suspect it was because of the low battery level.

i had auto-descent triggered once on my M2Z - it is possible. it was in the 45mph wind with gusts up to 50, so, it may happen. i bet MM did the same - went into an autolanding mode with partial control.

 

[Deleted member 109934]

I get why it didn't ascend on RTH because it was already over the RTH altitude. I also get why it didn't come back because it was fighting the wind.
By the way RTH as was said, is its own mode with same or similar attack angle limit which limits its airspeed. This is probably chosen as it is probably optimal for distance over energy. Sport mode allows a bigger attack angle which allows it more airspeed.

What I don't get is why it kept trying to land if it still had energy in the battery.

Yesterday I'm flying around, it is cold and windy but not too windy, I'm flying over the cliff taking sets of HDR photos about 300ft from my spot. I noticed 30% batt so I decided to manually come back, I'm flying back and while drone approaches I hear battery low (it was 20%) landing, I was lucky drone was already over the ground and platform I was standing on because it would land in the canyon. If did not land, but stopped and started landing procedure.
This is the second instance when at 20% it just decided to stop and land. Because of that I'm really scared when I see 30% battery left.

Does anyone know what it means "battery at a maximum distance?"

The first time when it land I did a flight length hover test in the basement and MM landed completely by itself. ( no scare because it was all controlled environment)

 

[Meta4]

Does anyone know what it means "battery at a maximum distance?"

It's the battery level at the most distant point of your flight.

 

[old man mavic]

i think that the new batteries are more affected by the cold than the lipos we are used to,until the temps improve, i think that we need to think about getting home when we see 50% if we are a way out ,it might be because they are only 2 cell that they run down faster as well

 

[Chrislaf]

i think that the new batteries are more affected by the cold than the lipos we are used to,until the temps improve, i think that we need to think about getting home when we see 50% if we are a way out ,it might be because they are only 2 cell that they run down faster as well

I was thinking about that too. I don’t have a MM but do have a Spark and P3S and do lots of flying in cold weather (below 0C). As long as my batteries are warm to begin with, there is no reduction in my flight times - both use LiPo’s. My Tello uses Li-ion and my flight time will drop from 10 minutes to 6 or 7 minutes in cold temps even though I start with a warm battery.

If I am not mistaken the mini uses Li- ion too so maybe that is a factor. What are the temps before and after a flight in cold weather for those that have an AirData account and a Mini?

Chris

 

[old man mavic]

i guess we will have to wait till someone who is flying in a warm part of the world ,tells us what sort of battery life they are getting

 

[blakamin]

wait till someone who is flying in a warm part of the world

Haven't pushed it yet because everytime I go outside, the wind doubles, or it starts raining (totally uncharacteristic for here)..

 

[TDZHDTV]

I was thinking about that too. I don’t have a MM but do have a Spark and P3S and do lots of flying in cold weather (below 0C). As long as my batteries are warm to begin with, there is no reduction in my flight times - both use LiPo’s. My Tello uses Li-ion and my flight time will drop from 10 minutes to 6 or 7 minutes in cold temps even though I start with a warm battery.

If I am not mistaken the mini uses Li- ion too so maybe that is a factor. What are the temps before and after a flight in cold weather for those that have an AirData account and a Mini?

Chris

Typical slope 4 deg C ambient air temp, I’d be interested in your thoughts. Cheers

 

[LeSchmoo]

Question (as I may have had a similar downward motion issue) - if the operator is holding the down elevation stick at the time connection is lost, does the drone continue on the that trajectory, or does it go into hover mode?

(In my case the drone went behind a sandbank and lost connection, it wasn't until later that I reviewed the video that it appeared to continue to the ground (sand not water thankfully) - I would need to cross reference with logs to be sure...

 

[DanMan32]

I'm pretty certain loss of signal usually translates to no stick input. It wouldn't make sense otherwise. Now if it is in an autonomous state, like RTH or auto-landing, that will probably continue.

 

[JSM]

The autodescent started around 4:26 with the battery at 22%.
It's different from what happens with other DJI drones which would come home at RTH height (or above if above RTH height) until directly above home or until the critically low battery level initiates autolanding to protect the drone.
This might be a new way for DJI to program the Mini but I can't be certain as I don't have one to test.
From 4:26, while autodescending, the drone is still attempting to RTH but being blown further away.
I suspect you could have had control even if not able to stop the autodescent.
There are several times when you gave it joystick input but they were too brief to see how they affected the flight.

Probably not against a headwind that was blowing it backwards in RTH mode.
At 17% you should already be home.
The battery is too low and would not last long pushing hard in Sport Mode.
You would have soon hit critical low battery level (if it wasn't already there) and the game would be over.

Strong headwinds are a serious problem that you have to understand and plan to avoid being stuck like this.
If it's a strong wind on the ground, it will be stronger up high. (Don't leave your drone up high when battling a strong headwind).
If you fly away going downwind, you have forced yourself to battle against a headwind for the return flight.


You started at 42% which really limits your flight options before you start.
Something goes wrong or you see something interesting that tempts you to stay up a little longer and before you know it, the drone is at critical low battery level and you have no options.
But it's probably more serious than that.
I don't know about the Mini, but the % indicator for all other DJI drones is only reliable if you start with a full battery.
It's very common to see fall-from-the-sky incidents when people launch with a battery that's been sitting around and actually has much less power than the % indicator suggests.

You should treat your fuel level as if you were flying in a real plane.
Only launch with a fully charged battery and always land with a healthy reserve fuel level.

Agree totally!!! just another addition to fail safe options when flying!

 

[JSM]

Look at RTH initiated at 4:50.8, which climbed from 93 feet to 115 ft at 5:04.1 (all the time trying to fly forward) and then started descending.
It never reached RTH height.

In all other DJI drones the RTH speed is significantly less than optimal speed for max distance.
No-one has ever come up with a credible reason for DJI to set RTH speed as slow as they do.

On the other Mavics (including Spark) you can still push full stick forward on RTH and gain X amount of extra speed, does the Mini have the same capabilitie ???

 

[WooZie]

no, it does not have, only you can to rotate yaw, not to change the directon or increase the speed, but if you cancel rth then you can do manually what you want

 

[Mac Man]

On the other Mavics (including Spark) you can still push full stick forward on RTH and gain X amount of extra speed, does the Mini have the same capabilitie ???

Speed can be changed, but In RTH the Mini returns in P-Mode at 8m/sec. That is the max speed. Per MM manual:

“During RTH, the aircraft’s speed, altitude, and the orientation can be controlled using the remote controller or DJI Fly if the remote controller signal is normal, but the direction of flight cannot be controlled.”

 

[paulatkin73]

Speed can be changed, but In RTH the Mini returns in P-Mode at 8m/sec. That is the max speed. Per MM manual:

“During RTH, the aircraft’s speed, altitude, and the orientation can be controlled using the remote controller or DJI Fly if the remote controller signal is normal, but the direction of flight cannot be controlled.”

RTH is the lousy way to fly back from a long distance, as, first of all, it uses the slow optimal angle to preserve battery that may have issues in section with severe wind, secondary is that it will try to fly by gps constantly correcting the heading and wating power on that. on bigger birds best way to avoid all that is to switch to ATTI mode and drive model home using map and you own common sense considering amount of power left and speed of wind to fight.
and until mavic mini will be hacked to allow either atti mode or angle adjustment, i guess, the count of models blown away by the light breeze will only increase.

 

[Mac Man]

RTH is the lousy way to fly back from a long distance, as, first of all, it uses the slow optimal angle to preserve battery that may have issues in section with severe wind, secondary is that it will try to fly by gps constantly correcting the heading and wating power on that. on bigger birds best way to avoid all that is to switch to ATTI mode and drive model home using map and you own common sense considering amount of power left and speed of wind to fight.
and until mavic mini will be hacked to allow either atti mode or angle adjustment, i guess, the count of models blown away by the light breeze will only increase.

You are absolutely right on all counts. People fighting the wind with a Mini should use sport mode and fly it back. As soon as they hit RTH the AC will slow down and lose the fight.

 

[DanMan32]

ATTI would be horrible for most.
Power for GPS course correction is negligible. The only reason locked heading in RTH would be bad is in not being able to avoid obstacles.

A couple years ago I would have crashed my P3 if it weren't for my ability to swerve in RTH. I was flying around a cell tower pole (wide berth) where I lost signal. When I regained signal, I was heading straight for the pole. I swerved (can't remember if I yawed or banked) and once the evasive action taken, it resumed heading to home point.
Dumb move to begin with, but at least I could quickly take evasive action.

 

[Meta4]

secondary is that it will try to fly by gps constantly correcting the heading and wating power on that. on bigger birds best way to avoid all that is to switch to ATTI mode.

GPS mode won't use any extra power (that could be measured).
But it will keep the drone on course.