Guorium Posted at 1-7 17:49
I contacted support for the engineers to look at. Others can look at the log I uploaded to phatomhelp

Thank you for the update you have given and thank you for contacting our DJI support team. Please keep us posted on the said issue. Thank you for your support.

  Here's something interesting  ,  

Eka Posted at 1-10 08:34
Yes, but after you overide it and start flying, it won't be able to use them anyway. Looking at all those posts about landing in water and general problems when flying over moving water, to me, seems like they  bring more bad than good. Maybe they are useful to beginners, but more advanced pilots might benefit more from disabling them. When that sensor feels ground and you input longer left stick down, AC goes into landing procedure. Then when going further down, more chance to lose signal and puting left stick up might not help. Now combine that with posible wrong reading from sensor above water and there you have a disaster.

The flight record did not record any sort of landing prompts. In my test flights later, manual landings are recorded even when cancelled by stick up. So far we cannot be sure if the mini got into some sort of automated landing due to wrong vps height without a record. My flight record had no warnings of any sorts when that drop occured.

That seems even more worrying. If drop was not caused by some sort of programmed procedure, but simply by not having enough power, maybe it's a hardware problem which can't be solved with a firmware update.

Eka Posted at 1-10 23:37
That seems even more worrying. If drop was not caused by some sort of programmed procedure, but simply by not having enough power, maybe it's a hardware problem which can't be solved with a firmware update.

I think they have turn the power of the motors a bit down to avoid the "not enough power" errors people had constantly on their screens, but now it doesnt hoover as stable and may be experiencing less throttle.

InspektorGadjet Posted at 1-11 11:04
I think they have turn the power of the motors a bit down to avoid the "not enough power" errors people had constantly on their screens, but now it doesnt hoover as stable and may be experiencing less throttle.

A loss of throttle that quickly like in my video? Hard to imagine

Unfortunately, there is no way to disable it at MM!

Eka Posted at 1-10 08:34
Yes, but after you overide it and start flying, it won't be able to use them anyway. Looking at all those posts about landing in water and general problems when flying over moving water, to me, seems like they  bring more bad than good. Maybe they are useful to beginners, but more advanced pilots might benefit more from disabling them. When that sensor feels ground and you input longer left stick down, AC goes into landing procedure. Then when going further down, more chance to lose signal and puting left stick up might not help. Now combine that with posible wrong reading from sensor above water and there you have a disaster.

Unfortunately, there is no way to disable it at MM!

rooller71 Posted at 1-12 01:50
Unfortunately, there is no way to disable it at MM!

Not in a proper way, but covering it might do the trick. There are some vids on yt and seems like it' working fine.

Eka Posted at 1-12 01:53
Not in a proper way, but covering it might do the trick. There are some vids on yt and seems like it' working fine.

Yes and thank you! I'm already informed!

Guys I may have uncovered the issue. Try flying at eye level in sport mode without touching the throttle stick. I was doing this repeatedly today over a shallow pool. The result is if there is a suddenly gust of wind my mini may find it difficult to hold altitude and dip. My theory is that higher airflow resulted in the barometer detecting a lowered pressure. When mini senses that and no manual inputs from the throttle stick it attempts to correct its own altitude. In my case, it dipped in an attempt to keep altitude without knowing that the pressure change is caused by a gust not an unexpected change in altitude from other factors rather than the pilot's intention. I hope I am making sense. My issue now is is that every unit's behaviour or just mine? You are welcome to repeat my test over grass or shallow water to test it. Just fly in a straight line really fast and hover occasionally, gusts may make it lose atitude.

I too noticed this sometimes, flying in S-mode forward and seeing the Mini drop in altitude without any input. As soon as I let go of the forward stick, the Mini climbs back up. This happened to me multiple times over tarmac, not water. I would not fly fast and low over water with the Mini, I would maintain at least a 5m height.

Ice_2k Posted at 1-16 01:10
I too noticed this sometimes, flying in S-mode forward and seeing the Mini drop in altitude without any input. As soon as I let go of the forward stick, the Mini climbs back up. This happened to me multiple times over tarmac, not water. I would not fly fast and low over water with the Mini, I would maintain at least a 5m height.

Thanks for the input. It was very helpful. I discovered the mini changes altitude (up) when traveling against headwind. When i fully stop it lowers itself to correct that. If I go backward fast with wind it drops altitude without input. Strangely after full stop it does not correct itself (try to go back up). It is as if the mini accidentally performs a droney. Side wind does not seem to affect the mini though, the fast low flight remained level. This was done on grass.

However my concern is of an other issue. During repeated straight fast and low fight over shallow water, mini bumped into some gusts. The gusts made the mini rock around its axis and lose altitude quite fast. Noticeably different compared to the effect of a straight fast flight without input. My first incident happened at 2200m altitude and the thin air made the fall even faster I reckon.

Guorium Posted at 1-16 01:45
Thanks for the input. It was very helpful. I discovered the mini changes altitude (up) when traveling against headwind. When i fully stop it lowers itself to correct that. If I go backward fast with wind it drops altitude without input. Strangely after full stop it does not correct itself (try to go back up). It is as if the mini accidentally performs a droney. Side wind does not seem to affect the mini though, the fast low flight remained level. This was done on grass.

However my concern is of an other issue. During repeated straight fast and low fight over shallow water, mini bumped into some gusts. The gusts made the mini rock around its axis and lose altitude quite fast. Noticeably different compared to the effect of a straight fast flight without input. My first incident happened at 2200m altitude and the thin air made the fall even faster I reckon.

Thanks for the tests!
They are hard to replicate but they do happen, interesting the fact that the barometer could have wrong readings and Mini is trying to compensate wrongly, some of my drops happened also in Sports mode and it dropped a lot more than it should, I have the feeling the first time that it happened to me if I didn't saw it and I didn't input left stick full up my mini would be now over some tree.

Since I can't start a new thread:
Anyone else had problems with humidity?

So apparently Mavic Mini is extremely suspectible of any kind of humidity. Twice I have suffered an uncontrollable altitude loss where I could do nothing. First one was in a +3C with high humidity(not precipitation) and MM just decided to F it and did a 30m plummit worse than a full descent on S mode. Luckily I was at 80m so I/it managed to recover.
The second time was with -1C and extreme humidity(still no rain at ground level). I had flown about 15mins when I saw a "Motor Error. Land with caution and inspect the propellors" on the screen. I immediately tried to land it to me, but the first downward command from the sticks send it plummiting again, luckily I was close enough to catch it.

Attached is a pic of the later flight's ice accumulation, took me by a surprise that this amount of buildup will literally drop it out of the sky, even if it is a minidrone...

Yeah the pic went missing...

InspektorGadjet Posted at 1-16 03:32
Thanks for the tests!
They are hard to replicate but they do happen, interesting the fact that the barometer could have wrong readings and Mini is trying to compensate wrongly, some of my drops happened also in Sports mode and it dropped a lot more than it should, I have the feeling the first time that it happened to me if I didn't saw it and I didn't input left stick full up my mini would be now over some tree.

That is a horrible feeling. I had the mini hover over water just meters away from me and a gust knocked it about half meter down. Second occasion occurred during a full speed ahead maneuver Low over water and I see it start dipping as soon as I feel a gust. Technically the barometer would be reading it correctly. It may just be the mini’s algorithm doing the foul play. I suspect if it senses a change in pressure and no stick input that could cause the change in pressure it deems it an unexpected change in altitude. Therefore it adjusts the throttle to get back to the pressure it expects but it would give the wrong altitude as a result. I am just curious to find out how many people observe the phenomenon where a gust could knock the mini down some height.

Guorium Posted at 1-16 04:53
That is a horrible feeling. I had the mini hover over water just meters away from me and a gust knocked it about half meter down. Second occasion occurred during a full speed ahead maneuver Low over water and I see it start dipping as soon as I feel a gust. Technically the barometer would be reading it correctly. It may just be the mini’s algorithm doing the foul play. I suspect if it senses a change in pressure and no stick input that could cause the change in pressure it deems it an unexpected change in altitude. Therefore it adjusts the throttle to get back to the pressure it expects but it would give the wrong altitude as a result. I am just curious to find out how many people observe the phenomenon where a gust could knock the mini down some height.

Yeah, something is fooling  the algorithm.
This happened to me in non windy days, either climb a bit, but mainly drop drastically, some times 5-6 meters and that is way too much.
I hope DJI is aware of this, many logs posted and they are looking in to it.

InspektorGadjet Posted at 1-16 05:08
Yeah, something is fooling  the algorithm.
This happened to me in non windy days, either climb a bit, but mainly drop drastically, some times 5-6 meters and that is way too much.
I hope DJI is aware of this, many logs posted and they are looking in to it.

Was your drone moving or stationary when that occurred. Also sometimes if the drone is far, the local wind can be very different. DJI just told me mine had a barometric sensor malfunction and wanted mine repaired for free. I doubt it is the sensor though...

Guorium Posted at 1-16 06:41
Was your drone moving or stationary when that occurred. Also sometimes if the drone is far, the local wind can be very different. DJI just told me mine had a barometric sensor malfunction and wanted mine repaired for free. I doubt it is the sensor though...

It happened after moving fast forward and letting sticks go, instead of hoover went down a lot.
I notice trying to fly in a straight line it also went down or up slightly and then it corrected somehow.
However the "drops" seem affected by something else.
Ill have to check myself directly with support.

Getting to the exact cause of this occurrence with this flight benefits us all, but I will repeat something that I think is extremely important (even if it is not related to the circumstances of this specific occurrence)...

Flying low over water is risky.  It does have an impact on the VPS, and a flyer's opportunity to recover from unexpected occurrences is incredibly small.  My most frequent use case for my drone is flying from my boat, and I try to keep at least 40' agl.  I've not lost any drones yet.

I have been flying for over two years, first a spark and then a Mavic Air, I still have the Mavic Air.  In all that time I have never experienced an uncontrolled decent from a drone, my Mini dropped 27ft and would not respond to control inputs.  There are at least 3 threads going on this forum now, different names but the same thing, uncontrolled behaviour.   I have posted my flight log and DJI have looked at it.  DJI raised a case and the drone is on its way back.

This is a very serious fault, it has nothing to do with water or wind, my drone simply decided to land with 50% battery,  The only messages received were the "power overload" messages on a perfectly calm day.

Just image flying this thing around a wedding or a birthday party and it decided to land in the middle of things.  Disaster.

Mavic Dave Posted at 1-16 09:20
I have been flying for over two years, first a spark and then a Mavic Air, I still have the Mavic Air.  In all that time I have never experienced an uncontrolled decent from a drone, my Mini dropped 27ft and would not respond to control inputs.  There are at least 3 threads going on this forum now, different names but the same thing, uncontrolled behaviour.   I have posted my flight log and DJI have looked at it.  DJI raised a case and the drone is on its way back.

This is a very serious fault, it has nothing to do with water or wind, my drone simply decided to land with 50% battery,  The only messages received were the "power overload" messages on a perfectly calm day.

I've noted the same thing Mavic Dave, that there are a few cases of unintended "drops" being reported, and that there doesn't appear (yet) to be a human related explanation.

Given my primary use case is flying over water, I'm a bit concerned.  I'm going to keep flying over land and keep LOS and either see if I have a similar occurrence, or I'll gain confidence that my craft doesn't behave unexpectedly.

Charles Adams Posted at 1-16 10:49
I've noted the same thing Mavic Dave, that there are a few cases of unintended "drops" being reported, and that there doesn't appear (yet) to be a human related explanation.

Given my primary use case is flying over water, I'm a bit concerned.  I'm going to keep flying over land and keep LOS and either see if I have a similar occurrence, or I'll gain confidence that my craft doesn't behave unexpectedly.

I would guess that some drones are affected by this and some are not.  Those that have the fault have a problem should be returned to DJI after a review of the flight log. Put simply, if the drone does not respond to control inputs then it has a fault.  Apart from a controlled landing by a drone when its battery is exhausted all other flying (and landing) should be under the control of the pilot.

DJI have a problem, the only question is how big it is.

Mavic Dave Posted at 1-17 00:30
I would guess that some drones are affected by this and some are not.  Those that have the fault have a problem should be returned to DJI after a review of the flight log. Put simply, if the drone does not respond to control inputs then it has a fault.  Apart from a controlled landing by a drone when its battery is exhausted all other flying (and landing) should be under the control of the pilot.

DJI have a probmel, the only question is how big it is.

From the flight log the up stick was probably working. It is just that the drone reacted slowly due to reasons like thin air up at 2200m.  The real issue is why it dropped altitude when a gust comes.

Guorium Posted at 1-26 03:46
From the flight log the up stick was probably working. It is just that the drone reacted slowly due to reasons like thin air up at 2200m.  The real issue is why it dropped altitude when a gust comes.

I was at more or less ground level, not 2000 metres.  There were no gusts, the Mini simply decended by itself.

Mavic Dave Posted at 1-26 11:25
I was at more or less ground level, not 2000 metres.  There were no gusts, the Mini simply decended by itself.

Do you mean sea level? What was under the mini when it descended?

Guorium Posted at 2-5 07:58
Do you mean sea level? What was under the mini when it descended?

I was about 30 feet above a river on a sunny day, the drone dropped 27 feet, then detected the water and bounced up.  I got a bit of control back and brought it home.

A little 30 second video showing area:

Mavic Dave Posted at 2-5 08:16
I was about 30 feet above a river on a sunny day, the drone dropped 27 feet, then detected the water and bounced up.  I got a bit of control back and brought it home.

A little 30 second video showing area:

Nice place! Kinda like where I had my incident. Do you have footage of the 27feet fall?

Guorium Posted at 1-26 03:46
From the flight log the up stick was probably working. It is just that the drone reacted slowly due to reasons like thin air up at 2200m.  The real issue is why it dropped altitude when a gust comes.

Altitude 2200m with Mavic Mini?  2200 meters?   

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MM_Pro Posted at 2-6 06:27
Altitude 2200m with Mavic Mini?  2200 meters?

Correct. I also completed a flight at 3500m hours before this flight coming down from the mountain. All good there but I did not get that close to the water at that time.

Guorium Posted at 2-6 14:16
Correct. I also completed a flight at 3500m hours before this flight coming down from the mountain. All good there but I did not get that close to the water at that time.

ah ok, here in Europe the MM is limited to 500m max altitude.

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MM_Pro Posted at 2-6 15:56
ah ok, here in Europe the MM is limited to 500m max altitude.

That 500m is measured from takeoff point. I was talking about elevation from sea level.

I have been saying for some time that the problem is caused by the movement of the mini causing pressure changes within the body of the aircraft. I do not believe that the barometer is misbehaving at all. The slightest pressure change translates to tens of feet of altitude, so the aircraft is very sensitive to the most minute pressure difference. And, although I do not own a mini, I tend to think that the vents designed into the body are what is causing the pressure changes.

I suspect that as the aircraft flies along at speed, the air moving through the vents causes a fall in pressure, translated to the aircraft ascending, but it maintains its current altitude because the pilot is controlling the aircraft. As soon as you stop, the flight controller is responsible for maintaining altitude, it then thinks the aircraft is too high, so it begins a descent to regain position. Then the pressure returns to normal because there is no forward movement, and the aircraft again rises back to where it should be.

DJI, in offering to replace the barometer in Guorium's aircraft, really don't have a clue as to the problem, these are simple component jockeys. I believe the problem is the body design with the vents having an unwanted effect on the performance of the aircraft. If I am correct, then no firmware/software change is going to cure the problem, it is a design fault in the body of the aircraft.

PS. I do not believe it has anything to do with temperature either, it is just an air pressure thing. And because it is all taking place inside the automated routines of the flight control system, I do not expect you will see anyting in the flight logs showing it occurring.

Geebax Posted at 2-6 18:42
I have been saying for some time that the problem is caused by the movement of the mini causing pressure changes within the body of the aircraft. I do not believe that the barometer is misbehaving at all. The slightest pressure change translates to tens of feet of altitude, so the aircraft is very sensitive to the most minute pressure difference. And, although I do not own a mini, I tend to think that the vents designed into the body are what is causing the pressure changes.

I suspect that as the aircraft flies along at speed, the air moving through the vents causes a fall in pressure, translated to the aircraft ascending, but it maintains its current altitude because the pilot is controlling the aircraft. As soon as you stop, the flight controller is responsible for maintaining altitude, it then thinks the aircraft is too high, so it begins a descent to regain position. Then the pressure returns to normal because there is no forward movement, and the aircraft again rises back to where it should be.

My log just shows descend without stick inputs. Like many other users. No errors. There is no way for the FC to distinguish what contributes to the pressure change (user stick input or wind). I guess DJI programed FC so that mini has to lock to its altitude (calculated from the baro's pressure readout) when the throttle stick is neutral. So a gust of air could have caused the drop as you said for my case. I am aware of other cases of drop on calm days and it could be caused by other sources. Given how random the occurrence of my issue has been, I think the random gust could have been the cause (see the flag blown around under the bridge).

I also find it hard to believe the baro is that susceptible to external wind since the baro faces the battery compartment (near the microusb port see pic). I think that location is quite shielded to allow for guadual pressure equilibrium but I am no aerodynamics expert so what do I know.



Not many people care to report. Many users are simple flyers, the drone comes home and it is all good. Many may not even notice. That could explain why not evenone is reporting this if it is a result of open vent design which is present on every mini. Do you see loss of altitude in your Phantom on gusty days?

Come on now.  This is clearly a Pilot problem!
Pilot failed to open drone up and remove shipping sealer from around mercury barometer inside drone.  

[Only kidding]      

Guorium Posted at 1-15 23:53
Guys I may have uncovered the issue. Try flying at eye level in sport mode without touching the throttle stick. I was doing this repeatedly today over a shallow pool. The result is if there is a suddenly gust of wind my mini may find it difficult to hold altitude and dip. My theory is that higher airflow resulted in the barometer detecting a lowered pressure. When mini senses that and no manual inputs from the throttle stick it attempts to correct its own altitude. In my case, it dipped in an attempt to keep altitude without knowing that the pressure change is caused by a gust not an unexpected change in altitude from other factors rather than the pilot's intention. I hope I am making sense. My issue now is is that every unit's behaviour or just mine? You are welcome to repeat my test over grass or shallow water to test it. Just fly in a straight line really fast and hover occasionally, gusts may make it lose atitude.

"it dipped in an attempt to keep altitude without knowing that the pressure change is caused by a gust not an unexpected change in altitude from other factors rather than the pilot's intention."

Begging question, why isn't drone's IMU countering the pressure change data?
IMU is supposed to monitor movements inline with XYZ axis and monitor movements around XYZ axis.  IMU should be sending data to drone's flight controller, essentially saying drone has not suddenly moved lower or higher.

HedgeTrimmer Posted at 2-6 20:13
"it dipped in an attempt to keep altitude without knowing that the pressure change is caused by a gust not an unexpected change in altitude from other factors rather than the pilot's intention."

Begging question, why isn't drone's IMU countering the pressure change data?

Very good question. IMU readout can indeed be considered by the FC to counter pressure change not induced by user intent. It probably already does it, otherwise mini cannot react to people grabbing and pulling it down by fighting its way back up. Perhaps DJI has some fw patching to do...

HedgeTrimmer Posted at 2-6 20:13
"it dipped in an attempt to keep altitude without knowing that the pressure change is caused by a gust not an unexpected change in altitude from other factors rather than the pilot's intention."

Begging question, why isn't drone's IMU countering the pressure change data?

Just to be clear about this, IMU refers to Inertial Measurement Unit, it is a collection of accelerometers measuring a change in direction in any one of 6 axis, it is not responsible for controlling anything. It is, like the barometer, VPS, GPS and gyros, simply an input to the Flight Controller (FC). Some accelerometer packages also contain the gyros as well.

Guorium Posted at 2-6 20:01
My log just shows descend without stick inputs. Like many other users. No errors. There is no way for the FC to distinguish what contributes to the pressure change (user stick input or wind). I guess DJI programed FC so that mini has to lock to its altitude (calculated from the baro's pressure readout) when the throttle stick is neutral. So a gust of air could have caused the drop as you said for my case. I am aware of other cases of drop on calm days and it could be caused by other sources. Given how random the occurrence of my issue has been, I think the random gust could have been the cause (see the flag blown around under the bridge).

I also find it hard to believe the baro is that susceptible to external wind since the baro faces the battery compartment (near the microusb port see pic). I think that location is quite shielded to allow for guadual pressure equilibrium but I am no aerodynamics expert so what do I know.

I don't think gusts of wind are the cause either, I think it is entirely due to the flight forward movement. One of the seemingly common denominators of this problem is that it usually happens after a period of forward flight,m often in Sport Mode. My theory is that the forward movement causes air to flow into the aircraft, and possibly causing a venturi effect over the aperture in the barometer, thus making the pressure slightly lower inside the barometer chamber.