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Flyaway and argument over setting home point at "launch"

RedBaron122

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I recently wanted to take some footage of my team doing a charity event by swimming the english channel. On a very slow moving, stable boat. I got my DJI Air out and it said the compass needed calibration and it was not allowed to fly. It told me to re calibrate the compass which I followed the on-screen instructions and did. The error disappeared and it said it was safe to fly with no error messages appearing - there was excellent GPS signal. It was excellent conditions too, clear visibility very slight breeze. I took off and immediately the drone drifted away from me before trying to settle. The drone kept drifting despite me trying to correct it. Without touching the controls it seemed to move. I tried to fly against the drift and it still drifted away, albeit slightly slower. I managed to control it a little but then it just kept flying away from me. I tried sport mode to push harder against the drift and get it back but still went away from me. I could see myself controlling it in the camera's view and was facing the drones front but despite pushing forwards towards myself it went away. Eventually the battery ran out and it dumped in the sea, I couldn't retrieve it for my DJI care refresh as it sunk.

DJI have looked at the flight record and say it was all pilot error. I was pushing hard to return it to me and it continued to drift away. Is this a known issue post callibration?

In addition, one of their arguments is around the home point. They state problems arose as the drone was 600m (max horizontal distance) from the home point which they say was automatically set when switching on the drone. Between switching on and flying it needed calibration therefore the boat I was on had drifted some distance during this calibration time. According to the manual however the set home automatic function is supposed to trigger on launch not on switching on the drone. I had assumed the homepoint would set on launch as per the manual and therefore the max horizontal distance would be from my launch location.
Is this an error? Or am I grasping, albeit correctly, at technicalities?
 
Do you have flight logs to post? If you do, post them here and one of the clever folk here will help you to understand what went wrong.
 
unfortunately it was a combination of compass error and a conflict between the compass and IMU, was it a steel hulled boat, if so even if you calibrated the compass magnetic north would still be compromised by the boat, also the fact that you had moved away from the original home point would cause a conflict in the drone and when you got aloft the drone no longer knew where it was, and was probably trying to get back to its original home point
 
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Yeah, calibrating and take off from a moving platform/boat introduces extra variables and it’s going to be hard to predict the behavior after launch. The software engineers at DJI probably don’t test their code under such scenarios.
 
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I recently wanted to take some footage of my team doing a charity event by swimming the english channel. On a very slow moving, stable boat. I got my DJI Air out and it said the compass needed calibration and it was not allowed to fly. It told me to re calibrate the compass which I followed the on-screen instructions and did. The error disappeared and it said it was safe to fly with no error messages appearing - there was excellent GPS signal. It was excellent conditions too, clear visibility very slight breeze. I took off and immediately the drone drifted away from me before trying to settle. The drone kept drifting despite me trying to correct it. Without touching the controls it seemed to move. I tried to fly against the drift and it still drifted away, albeit slightly slower. I managed to control it a little but then it just kept flying away from me. I tried sport mode to push harder against the drift and get it back but still went away from me. I could see myself controlling it in the camera's view and was facing the drones front but despite pushing forwards towards myself it went away. Eventually the battery ran out and it dumped in the sea, I couldn't retrieve it for my DJI care refresh as it sunk.

DJI have looked at the flight record and say it was all pilot error. I was pushing hard to return it to me and it
continued to drift away. Is this a known issue post callibration?

In addition, one of their
arguments is around the home point. They state problems arose as the drone was 600m (max horizontal distance) from the home point which they say was automatically set when switching on the drone. Between switching on and flying it needed calibration therefore the boat I was on had drifted some distance during this calibration time. According to the manual however the set home automatic function is supposed to trigger on launch not on switching on the drone. I had assumed the homepoint would set on launch as per the manual and therefore the max horizontal distance would be from my launch location.
Is this an error? Or am I grasping, albeit correctly, at technicalities?

Retrieve the txt flight log from your mobile device and post it here. That, plus the DAT file that will be identified in the txt log, will almost certainly explain exactly what happened.

TXT log: DJI Flight Log Viewer | Phantom Help
 
I recently wanted to take some footage of my team doing a charity event by swimming the english channel. On a very slow moving, stable boat. I got my DJI Air out and it said the compass needed calibration and it was not allowed to fly. It told me to re calibrate the compass which I followed the on-screen instructions and did. The error disappeared and it said it was safe to fly with no error messages appearing - there was excellent GPS signal. It was excellent conditions too, clear visibility very slight breeze. I took off and immediately the drone drifted away from me before trying to settle. The drone kept drifting despite me trying to correct it. Without touching the controls it seemed to move. I tried to fly against the drift and it still drifted away, albeit slightly slower. I managed to control it a little but then it just kept flying away from me. I tried sport mode to push harder against the drift and get it back but still went away from me. I could see myself controlling it in the camera's view and was facing the drones front but despite pushing forwards towards myself it went away. Eventually the battery ran out and it dumped in the sea, I couldn't retrieve it for my DJI care refresh as it sunk.

DJI have looked at the flight record and say it was all pilot error. I was pushing hard to return it to me and it
continued to drift away. Is this a known issue post callibration?

In addition, one of their
arguments is around the home point. They state problems arose as the drone was 600m (max horizontal distance) from the home point which they say was automatically set when switching on the drone. Between switching on and flying it needed calibration therefore the boat I was on had drifted some distance during this calibration time. According to the manual however the set home automatic function is supposed to trigger on launch not on switching on the drone. I had assumed the homepoint would set on launch as per the manual and therefore the max horizontal distance would be from my launch location.
Is this an error? Or am I grasping, albeit correctly, at technicalities?
Sorry to hear that you lost your Mavic Air. It's a really nice drone.

I don't think we can tell the full story without flight logs. However from what you've said, I would say that there was at least some level of pilot error. Taking off, flying, and landing on a boat is more difficult than doing so from land. As such, it takes a pilot who knows not only how to fly but is very well aware of how all of the drone's systems and sensors work. I see some mistakes right from the start:
  • I would never do a compass calibration from a boat. There is just too much metal around. If it is necessary, a compass calibration on the shore before getting on the boat would be better.
    An immediate warning would be the MA not letting you take off due to magnetic interference. The calibration in this case allowed you to take off but now the IMU and compass may have not agreed, and that's bad for flying.
  • You assumed that the home point is set on launch. That is not true. It also is not set immediately when switching on. The Home Point is automatically set at some point after powering on. It is set once the drone has enough satellites locked to accurately set the home point. You should always wait till that happens before launching. It is very evident in DJI Go 4 when the home point is established.
  • Even with no compass issues and a properly set Home Point, the drone would immediately seem to drift because the boat itself is drifting. If it did not have a GPS lock, it would try to maintain position via VPS if it was low enough. However once it got over water, even that would most likely not work right.
It seems there may have been many contributing factors here but we can probably tell more once the logs are available. Launching with potential compass errors and no Home Point though probably sealed its fate from the very start.
 
Sigh!......









 
Oh the boat post is so much doom and gloom. Got that horrible sinking feeling... :(
Probably an expensive way to live and learn.
Attached dat file and text (I think)

Thanks for your help at this sad time. :oops:
 

Attachments

  • 19-09-15-09-21-33_FLY069.DAT
    6.3 MB · Views: 8
  • DJIFlightRecord_2019-09-15_[09-23-40].txt
    1.4 MB · Views: 9
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According to the manual however the set home automatic function is supposed to trigger on launch not on switching on the drone. I had assumed the homepoint would set on launch as per the manual and therefore the max horizontal distance would be from my launch location.
Is this an error? Or am I grasping, albeit correctly, at technicalities?

From your post I take it this was one of your first flights with a drone? Sorry that you lost it. Before flying again with an expensive drone, I recommend you go buy a Syma X5 (~$40) and learn to fly it. There is no GPS, nothing fancy, just a fun and nearly unbreakable little drone that you can fly indoors or outdoors. Developing the ability to hover this 'unassisted' drone and maneuver it will greatly help you fly a Mavic in the long run and be able to avoid a few pitfalls.

Setting homepoint occurs when it says "Homepoint Recorded" audibly and visually. It happens when it has acquired minimum GPS satellite locks to accurately set your position. My experience, takes maybe 30 seconds after turn on. Might be faster or longer. If you turned it on, it achieved lock, and then you drifted 600m before launching you have set yourself up for failure. You must re-record the new homepoint (via DJI app) when you go to launch if you want it to return to that spot. On a boat this is quite difficult at best and you will be manually landing in order to get it on the boat.
 
Last edited:
Oh the boat post is so much doom and gloom. Got that horrible sinking feeling... :(
Probably an expensive way to live and learn.
Attached dat file and text (I think)

Thanks for your help at this sad time. :oops:

That's a strange one. The aircraft responded appropriately to rudder and throttle inputs, but only very sporadically to elevator and aileron inputs. Here are the data for elevator and pitch:

Pitch.png


The DAT event stream contains numerous RC connection and battery errors but it's not clear to me in what way they are related to the problem. The motor PWM data show that the FC was simply ignoring the stick commands.

This needs more investigation.
 
That's a strange one. The aircraft responded appropriately to rudder and throttle inputs, but only very sporadically to elevator and aileron inputs. Here are the data for elevator and pitch:

The DAT event stream contains numerous RC connection and battery errors but it's not clear to me in what way they are related to the problem. The motor PWM data show that the FC was simply ignoring the stick commands.

This needs more investigation.
Is that because of this warning message at 9:13.2 : Maximum flight distance reached. Adjust the distance in MC Settings if required.
The OP had set a Max Distance limit and the drone couldn't push past that.
 
Is that because of this warning message at 9:13.2 : Maximum flight distance reached. Adjust the distance in MC Settings if required.
The OP had set a Max Distance limit and the drone couldn't push past that.

Brilliant. Yes - I didn't think to check that. The OP was mostly trying to fly away from the home point, and once the aircraft reached the limit it simply refused to go further. The home point was the launch point, and there was no attempt to fly it back there. Perhaps the OP was unaware how far the boat had drifted during the flight.
 
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The home point was the launch point, and there was no attempt to fly it back there. Perhaps the OP was unaware how far the boat had drifted during the flight.
Actually the launch point was 860 feet from the recorded home point.
The drone was left for some time after powering up while the boat shifted considerably before launching.
 
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Before flying again with an expensive drone, I recommend you go buy a Syma X5 (~$40) and learn to fly it. There is no GPS, nothing fancy, just a fun and nearly unbreakable little drone that you can fly indoors or outdoors. Developing the ability to hover this 'unassisted' drone and maneuver it will greatly help you fly a Mavic.
It only takes a few minutes to learn the basics of controlling the drone and a Mavic is going to be much easier to fly than a cheap toy drone anyway.
The important things to learn are what can go wrong and how to prevent them from becoming a problem.
Since so much of that is related to the app, a cheap drone really isn't much use as a learning aid.
 
There are a lot of things that can go wrong and to become a proficient flyer one needs to have an understanding of these potential issues and know how to prevent them from causing a problem, as well as having a good understanding of how the drone and its programming works.
Flying from a boat introduces some particular complexities that land-based flyers won't ever encounter.
And at sea, you are flying in an unforgiving environment where one mistake can often mean coming home with one less drone than you went out with.
On a very slow moving, stable boat. I got my DJI Air out and it said the compass needed calibration and it was not allowed to fly. It told me to re calibrate the compass which I followed the on-screen instructions and did. The error disappeared and it said it was safe to fly with no error messages appearing - there was excellent GPS signal. It was excellent conditions too, clear visibility very slight breeze. I took off and immediately the drone drifted away from me before trying to settle. The drone kept drifting despite me trying to correct it. .... Eventually the battery ran out and it dumped in the sea, I couldn't retrieve it for my DJI care refresh as it sunk.
It looks like this flight had a high probability of ending badly because the operator did not have a good awareness of how the drone works or the special issues encountered at sea.
Your drone was perfectly controllable but issues with a Max Distance limit confused you.

DJI have looked at the flight record and say it was all pilot error. I was pushing hard to return it to me and it continued to drift away. Is this a known issue post callibration?
I can see why DJI would blame operator inexperience as it was operator confusion and misunderstanding that cause the loss of the drone.
There is no issue post calibration.
In addition, one of their arguments is around the home point. They state problems arose as the drone was 600m (max horizontal distance) from the home point which they say was automatically set when switching on the drone. Between switching on and flying it needed calibration therefore the boat I was on had drifted some distance during this calibration time. According to the manual however the set home automatic function is supposed to trigger on launch not on switching on the drone. I had assumed the homepoint would set on launch as per the manual and therefore the max horizontal distance would be from my launch location.
Is this an error? Or am I grasping, albeit correctly, at technicalities?
DJI's explanation isn't very clear but what they were trying to say was correct.
Compass calibration was not necessary anyway.
The compass was warning you of steel items close to where you placed the drone.
Simply lifting the drone away from the magnetic field the compass warned about was all that was necessary.
The home point was recorded soon after powering up the drone but the boat moved 860 feet from the recorded home point before you got around to launching.
You ran into what you perceived as control problems when the drone would not fly through the invisible wall created by the Max Distance limit you had set at 600 metres from wherever the home point was recorded.

After the confusion at the start of the flight, you reset the homepoint at 11:01.9.
The drone is now 3900 feet from the boat's current position and well out of sight.
Because of the Max Distance limit, it can't fly further away but can be flown home.
RTH is initiated at 11:10.8 and the RTH is left to bring the drone back automatically.
At an altitude of 162 feet, the RTH (hands-off) can only make 6.5 mph towards where the boat was when the home point had been reset.
Autolanding is initiated at 14:21 with the drone 668 feet from the recorded home point - but by now the boat's position is unknown.
Autolanding puts the drone in the water at 14:55.8 with >3.5 volts showing in all battery cells.

I didn't find the reason for Autoland to be initiated.
Perhaps @sar104 can.
 
Dude- I don't have enough experience to offer any technical support, but I have lost (and fortunately recovered) my Mavic Pro so I know a little of what you may be feeling.

Just wanted to say I'm sorry to read you lost your unit. It's a pinch in the wallet, but get another, add a few things to make it a new level experience and get back into the air. Good luck!
 
There are a lot of things that can go wrong and to become a proficient flyer one needs to have an understanding of these potential issues and know how to prevent them from causing a problem, as well as having a good understanding of how the drone and its programming works.
Flying from a boat introduces some particular complexities that land-based flyers won't ever encounter.
And at sea, you are flying in an unforgiving environment where one mistake can often mean coming home with one less drone than you went out with.

It looks like this flight had a high probability of ending badly because the operator did not have a good awareness of how the drone works or the special issues encountered at sea.
Your drone was perfectly controllable but issues with a Max Distance limit confused you.


I can see why DJI would blame operator inexperience as it was operator confusion and misunderstanding that cause the loss of the drone.
There is no issue post calibration.

DJI's explanation isn't very clear but what they were trying to say was correct.
Compass calibration was not necessary anyway.
The compass was warning you of steel items close to where you placed the drone.
Simply lifting the drone away from the magnetic field the compass warned about was all that was necessary.
The home point was recorded soon after powering up the drone but the boat moved 860 feet from the recorded home point before you got around to launching.
You ran into what you perceived as control problems when the drone would not fly through the invisible wall created by the Max Distance limit you had set at 600 metres from wherever the home point was recorded.

After the confusion at the start of the flight, you reset the homepoint at 11:01.9.
The drone is now 3900 feet from the boat's current position and well out of sight.
Because of the Max Distance limit, it can't fly further away but can be flown home.
RTH is initiated at 11:10.8 and the RTH is left to bring the drone back automatically.
At an altitude of 162 feet, the RTH (hands-off) can only make 6.5 mph towards where the boat was when the home point had been reset.
Autolanding is initiated at 14:21 with the drone 668 feet from the recorded home point - but by now the boat's position is unknown.
Autolanding puts the drone in the water at 14:55.8 with >3.5 volts showing in all battery cells.

I didn't find the reason for Autoland to be initiated.
Perhaps @sar104 can.

Okay - I had a chance to take a proper look at this. You are quite right - the boat drifted after startup, and the launch point (labeled "Home") is not the initial or reset home point:

screenshot255.jpg

The aircraft flew south until it hit the maximum flight distance, and then went no further. The boat was likely further south than that, and it could not follow it. Eventually, at 662 seconds, the home point was reset further south, and the aircraft entered RTH. Unfortunately before it could reach the boat the battery level fell below the computed LandBattery level, and the FC switched to autolanding, around 670 m short of the second home point. By then, presumably, the boat was even further south (another 400 m if it continued at its average drift rate of 2 m/s between the launch and home point reset).

Battery.png

So it would have landed around 1 km north of the boat at that point.
 
Is that because of this warning message at 9:13.2 : Maximum flight distance reached. Adjust the distance in MC Settings if required.
The OP had set a Max Distance limit and the drone couldn't push past that.
First of all, great job to all the log experts here who pieced together the entire picture of what went wrong here. Bravo!!

It only takes a few minutes to learn the basics of controlling the drone and a Mavic is going to be much easier to fly than a cheap toy drone anyway.
The important things to learn are what can go wrong and how to prevent them from becoming a problem.
Since so much of that is related to the app, a cheap drone really isn't much use as a learning aid.
With all due repsect to @Meta4 , I believe that flying a cheap toy drone is of great value exactly because it is harder to fly than any DJI drone. This gives the pilot better skills on the sticks, and forces them to concentrate on actually flying the drone and maintaining spatial orientation. I believe those skills are important and necessary to the proper operation of any drone. Admittedly it would have not helped at all in this case.

There are a lot of things that can go wrong and to become a proficient flyer one needs to have an understanding of these potential issues and know how to prevent them from causing a problem, as well as having a good understanding of how the drone and its programming works.
Flying from a boat introduces some particular complexities that land-based flyers won't ever encounter.
And at sea, you are flying in an unforgiving environment where one mistake can often mean coming home with one less drone than you went out with.
Here is the crux of the entire story. Just because DJI has made these drones so simple to launch and control, does not mean that a pilot needs to be any less aware of everything involved in a flight. This is something I see as lacking over and over and over again. The skills that I feel are necessary:
  • Total familiarity with the craft, controller, software, and other systems to the point of it being second nature. If you don't know how the system will behave in any given scenario then you will at some point get in trouble. In this case it comes down to knowing how the maximum flight distance feature works. Not knowing about how the home point feature works and magnetic interference were contributing factors as well.
  • Spatial orientation. Learning how to control the craft no matter what its current orientation and velocity are crucial skills.
  • Situational awareness. A pilot always needs to know how the environment, weather, and all other external factors will affect the flight. In this case, launching from a drifting/moving boat was something that directly contributed to the loss. Launching and landing from any moving platform always has its specific challenges and these must be planned on and accounted for before launch.
  • Advance planning and always thinking about what to do if something goes wrong. Go over the failure scenarios in your head and be ready to react promptly with a plan to salvage the operation safely.
Sorry for the loss, but this is an excellent opportunity for others to learn.
 
I probably wouldn't recommend a Syma X5 as they don't have height hold. I have the Tello which can be had for less than $100, similar in control as the Mavic but nearly as resilient to crashes as the Syma. The only weak part of the Tello is the props can easily fly off when struck, and can be hard to find where it went. But extra props are cheap.
Charger and remote are extra though.
 
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