DJI almost sank my Mavic.

[Meta4]

I have launched my Mavic 2s with no Gps. It launches in Atti mode and will only allow the drone to fly around 20-50 ft high. Then only lets me fly horizontally for maybe 100 feet. That's my experience with no GPS signal.

The drone should have no horizontal distance limit without GPS, because it has no way to measure distance without GPS.

Here's the relevant section from the manual relating to height limits without GPS.

Height is restricted to 16 ft (5 m) when there is no GPS signal and Downward Vision System is activated. Height is restricted to 98 ft (30 m) when there is no GPS signal and Downward Vision System is inactivated.​

DJI recycled the same information in all the Mavic manuals, but there is no way to disable the downward sensors for those models using the Fly app so they won't go higher than 16 ft without PS.

 

[SabrToothSqrl]

Suppose the drone made it to the tarmac. It lands on the planes wing?
LOL

gets sucked into the engine. more dramatic.

 

[SabrToothSqrl]

I have launched my Mavic 2s with no Gps. It launches in Atti mode and will only allow the drone to fly around 20-50 ft high. Then only lets me fly horizontally for maybe 100 feet. That's my experience with no GPS signal.

Maybe that means it's not too far to get to a safe spot with the 90 second timer...

 

[SabrToothSqrl]

Well, I had to find a lightning to USBC so I could hook my iphone to my Mac. Haven't had to do that since I had to authorize my other phone so I could upload apps to it that I wrote. (learning Swift (in between other projects) too for fun). Love that we get to change ports every few years and get 100 more cables... Next iPhone better have USBC on it.

I was able to get to /DJI Fly / Flight Records, but it's showing as "Zero KB". I was in the app the other day before planning to pull the logs and cleaning things out because it said it had 20GB worth of stuff in it... Nothing I flew was intresting enough to be worth the space.

Can you pull logs from the drone directly? It has a USBC on it I think. I've never used it for anything, not sure what it's for..?

It's raining today, else I'd go for a flight just to see what the logs look like. I'll wait until it clears up a bit so I can get a log just to see what they look like and what's in them....

 

[Meta4]

Can you pull logs from the drone directly? It has a USBC on it I think. I've never used it for anything, not sure what it's for..?

The log is a .txt file in the app on the phone.
But you've given enough info already to know the basics.
You launched without waiting for GPS and for a homepoint to be recorded.
So the drone had no idea where it was.
Sometime later, it picked up enough GPS sats and got location data, which was inside a no-fly zone.
That triggered the auto-landing.

Had you waited for GPS and a homepoint before launching, if the launch point was inside the NFZ, the drone would have refused to launch.
Or if you were outside you could have launched but when you tried to fly into the NFZ, it would have been like bumping into a soft invisible wall.
The drone could have flown left and right along the wall, up and down or backwards, but you could not fly into it.

 

[SabrToothSqrl]

Authorization zone. Not a no-fly zone.
Forced landing. Not Auto-landing. And it was over water at the time. So, fun stuff.

 

[chazzm]

DJI "allowed" the drone to take off, only to force a landing shortly after. Yes I blame them.

I will look into how to pull the data.

I just read that switching between S and P mode and back will cancel a forced landing. Is that accurate?

Yes it will! Also flying over water I turn off my bottom sensors! Remember just because you can take off doesn’t mean it’s ready! No where does DJI garrentee safe take off and landing!!

 

[Meta4]

I just read that switching between S and P mode and back will cancel a forced landing. Is that accurate?

Not necessarily
If you've initiated the forced landing, it would stop it.
If the forced landing was due to flying into a no fly zone without GPS, no, you can't stop that.

 

[Capt KO]

Lesson learned, hopefully. Always wait for the voice prompt saying homepoint has been updated, please check it on the map. Green banner with gps. Only then does it know if it’s in a no-fly zone. Also water tends to suck in drones when too low. Sensors cannot “see” water as a hard surface causing Uncommanded decents. Enjoy

 

[Galeforce1]

Sounds to me that it was doing what it was programmed to do, which puts the responsibility back on you. It is not DJI's 'fault' when the drone works as it should.

 

[SabrToothSqrl]

Sounds to me that it was doing what it was programmed to do, which puts the responsibility back on you. It is not DJI's 'fault' when the drone works as it should.

How can it be my responsibility when I'm not in control?
Can you post the page number 'forced landing' is referenced in the owners manual?
I was unable to locate it.

No where in the manual is forced landing referenced, stated, or explained.
DJI took unauthorized control of my drone, without my permission, and almost sank it.
If the operation of my drone is "my responsibility" then I must be in control of it. A forced landing is not under my control. DJI was in control of it.

https://dl.djicdn.com/downloads/Mavic_Air_2/Mavic_Air_2_User_Manual_v1.4_en.pdf

I assure you, I read the manual prior to use, have used it multiple times without issue, while adhering to FAA rules and regulations. However I cannot perform an action when it's not stated in the very manual of the device.

I'll make a new thread explaining what I learned about forced landings, to compensate for DJIs lack of definition. I can't Imagine I have any pull with DJI, however if someone can ask them to include this information in the manual, maybe it will help others.

 

[Rattydude77]

How can it be my responsibility when I'm not in control?
Can you post the page number 'forced landing' is referenced in the owners manual?
I was unable to locate it.

No where in the manual is forced landing referenced, stated, or explained.
DJI took unauthorized control of my drone, without my permission, and almost sank it.
If the operation of my drone is "my responsibility" then I must be in control of it. A forced landing is not under my control. DJI was in control of it.

https://dl.djicdn.com/downloads/Mavic_Air_2/Mavic_Air_2_User_Manual_v1.4_en.pdf

I assure you, I read the manual prior to use, have used it multiple times without issue, while adhering to FAA rules and regulations. However I cannot perform an action when it's not stated in the very manual of the device.

I'll make a new thread explaining what I learned about forced landings, to compensate for DJIs lack of definition. I can't Imagine I have any pull with DJI, however if someone can ask them to include this information in the manual, maybe it will help others.

If you post th seen flight logs the guessing games would stop and we could find out who's at fault its that easy

How can it be my responsibility when I'm not in control?
Can you post the page number 'forced landing' is referenced in the owners manual?
I was unable to locate it.

No where in the manual is forced landing referenced, stated, or explained.
DJI took unauthorized control of my drone, without my permission, and almost sank it.
If the operation of my drone is "my responsibility" then I must be in control of it. A forced landing is not under my control. DJI was in control of it.

https://dl.djicdn.com/downloads/Mavic_Air_2/Mavic_Air_2_User_Manual_v1.4_en.pdf

I assure you, I read the manual prior to use, have used it multiple times without issue, while adhering to FAA rules and regulations. However I cannot perform an action when it's not stated in the very manual of the device.

I'll make a new thread explaining what I learned about forced landings, to compensate for DJIs lack of definition. I can't Imagine I have any pull with DJI, however if someone can ask them to include this information in the manual, maybe it will help others.

Flight logs and we could all find out who's fault it is common flight logs hahaha

 

[Meta4]

How can it be my responsibility when I'm not in control?

Since we've not seen the flight data, all we can do is guess based on the sketchy description of the incident.
But from what's been said, the most likely explanation is that while you were in control of the drone, you launched without waiting for GPS location data (which would have identified the NFZ and prevented landing), and flew off into a no-fly zone.

If you want to avoid guessing and work with more precise information ...
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a report on the flight data.
Come back and post a link to the report it provides, even if the report looks empty.

 

[SabrToothSqrl]

Please see post #24. I don't seem to be able to get the logs - folder shows zero kb when I browse to it with no files in it. It's moot anyway, the problem is the scenario and resulting situation is not defined in the manual. If I can safely recreate the situation I will get logs at that time and post them. All that's needed to prevent this is to have that information available in the owners manual.

 

[z28lt1]

Please see post #24. I don't seem to be able to get the logs - folder shows zero kb when I browse to it with no files in it. It's moot anyway, the problem is the scenario and resulting situation is not defined in the manual. If I can safely recreate the situation I will get logs at that time and post them. All that's needed to prevent this is to have that information available in the owners manual.

Couple of thoughts/notes:

-As for the manual, its a good point that this behavior is not described anywhere. However, they do tell you not to fly if you have weak GPS, so while they don't list the outcome, you can't totally blame the "manual". Anyone who takes off without good GPS signal is violating the safety guidelines (which is a separate doc from the manual)



-As for the logs, while the more details the better to know exactly what is going on, I'm not sure they are that useful in this case. We've seen before that if the drone acquires a GPS signal while in an authorization zone, it will land, which appears to be what happened here. Not sure we'll learn much more.

-As for the DJI forced landing, I'm not sure what the "proper" solution is. Yes, it could land in water, but that's much better than hitting an aircraft. There is no homepoint to go back to (and even if there was, is is certainly not a good idea for DJI to fly autonomously through an authorization zone, without authorization). If DJI just let the user do what he/she wants and fly on their own, they are giving the user an easy way out of the geofencing, by getting in before GPS is aquired. I'm really not sure what the right answer is. Forced landing could end up bad, but probably is the best solution

-Moral of the story is 1)Make sure you have strong GPS before taking off, and 2)Don't fly in an authorization zone unless you have entered your authorization.

 

[SabrToothSqrl]

I agree - now that i know more, I won't be taking off without full GPS any time soon. I just would like the scenario outlined in the manual, and even a step farther would be a setting of "allow take-off without GPS" (Yes/No) defaulted to "no".

It's all a learning process. I don't know what the best solution is, I'd think if the drone was limited to a few feet off the ground 2-3 or even 5' maybe would be better than forced landing. Once the drone has GPS, the app has all it needs to know where home is (GPS of the phone). I'd have to think long and hard about the 'best' solution, and understand that allowing drones to fly near aircraft/other hazards is 'bad' as well... of course some drones have no GPS, geo fencing, or could be 'hacked'... I'm not looking to go down that path, but someone with a drone with GPS and 'some' software brains should have some options other than forced 'landing' on water.

Overall I'm still very happy w/the drone (other than DJI releasing a better version 40 days later). But I know tech can't sit still forever. (I'd really like the sideways collision sensors).

In all, just hoping others can learn from my lack of complete understanding, and maybe DJI can make some simple improvements so this would not occur to others.

 

[Meta4]

There is no homepoint to go back to

Your drone records a homepoint wherever it is when it first gets good GPS location data.
If you are impatient land launch prematurely, it will record a homepoint as it's being flown out.

 

[Meta4]

Once the drone has GPS, the app has all it needs to know where home is (GPS of the phone).

Your drone's home point comes from the drone's GPS receiver and is recorded when the drone first gets good GPS data, whether that's on the ground or later in flight if you are impatient.
It never comes from your phone or tablet.

 

[z28lt1]

Your drone records a homepoint wherever it is when it first gets good GPS location data.
If you are impatient land launch prematurely, it will record a homepoint as it's being flown out.

Yes, but in this case, when it got GPS, it realized it was in an authorization drone and began to land. Unless there was a delay in acquiring GPS until if "figured out" it was in an authorization zone, the home point is exactly where it is. So I guess, technically you are correct and I am not that there IS a home point. It's just exactly where the drone is, so my point of "no homepoint to go back to" is correct in the practical sense of the word if not technical.

Maybe that is a reason to see a log file in a case like this, to see what if there is any delay between acquiring GPS and recognizing the authorization zone, although that is just theoretical conversation for this thread, because it doesn't change what happened to the OP.

 

[Meta4]

so my point of "no homepoint to go back to" is correct in the practical sense of the word if not technical.

There is a home point and the drone would return to if RTH was initiated.
It's just not the homepoint that an impatient flyer might imagine his drone would fly back to.

And on gaining good GPS location data, recognition that the drone was in an authorisation area would have been almost instantaneous.