If you took off from the top of a mountain and flew down hill, how far would you be able to go? Would the quad be limited to -500m?
Negative AGL
- Thread starter b0dyr0ck2006
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try taking off from a flat shed roof or wheely bin and land on the ground. let us know what happens 
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N017RW
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Meta4
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I've seen people suggest there is a limit but never seen anyone test it to confirm.
It would be interesting to know, theoretically there should be the same limit both up as well as down
N017RW
Premium Pilot
Ok, let's suppose you go to the top of the burj khalifa. You take off from the roof and the quad sets your AGL at 0. You then to proceed to fly down the outside of the building (829.8 metres tall). Would the quad plateau at 500 metres or continue to the bottom?
N017RW
Premium Pilot
There's no limit.
You should be able to derive the answer from that statement.
Why do you choose -500M? Why not -550, -220, -1000, -15000?
There's no limit as there is no need for such.
Please post any DJI documented information to the contrary.
The 'folklore' being generated here does not count.
You should be able to derive the answer from that statement.
Why do you choose -500M? Why not -550, -220, -1000, -15000?
There's no limit as there is no need for such.
Please post any DJI documented information to the contrary.
The 'folklore' being generated here does not count.
Perhaps I have read the tone of your message wrong, I'm looking for actual documentation or proof, not supposition. I'm not going to read between the lines and create my own answer for 'limits must be expressly created and there is no need for such thing' as a definite no limit.
The reason I 'chose' 500 metres is because that is the maximum flight height, so logic would dictate -500 metres.
Using my example of flying off of the burj khalifa you could in essence fly around Dubai at at height of 1329M which is obviously well above the regulation
The reason I 'chose' 500 metres is because that is the maximum flight height, so logic would dictate -500 metres.
Using my example of flying off of the burj khalifa you could in essence fly around Dubai at at height of 1329M which is obviously well above the regulation
N017RW
Premium Pilot
The pressure sensor is relative not absolute. It has no idea of true altitude against any datum.
When you take off from whatever building or structure you choose the a/c will assign that baro pressure to Zero feet in altitude. So yes you can fly another 500m above that point.
What you call 'logic' in that there must be an equal negative limit, I call supposition.
Please give an example why you feel there is a logical need for a limit?
I can think of no reason to prevent an a/c from landing as such a [negative] limit would create.
When you take off from whatever building or structure you choose the a/c will assign that baro pressure to Zero feet in altitude. So yes you can fly another 500m above that point.
What you call 'logic' in that there must be an equal negative limit, I call supposition.
Please give an example why you feel there is a logical need for a limit?
I can think of no reason to prevent an a/c from landing as such a [negative] limit would create.
The 500 m limit (specifically the 500 m above takeoff point limit) does not correspond to any regulation, so trying to relate them is pointless. And yes - if you can find a high point to launch from, whether it be a mountain or a building, then you can fly over nearby, lower-elevation areas at an altitude above 500 m AGL. That's not inconsistent, since the 500 m limit is not an AGL limit in the first place - the aircraft does not know its height above the ground.
In terms of a negative (again relative to takeoff) limit, the point being made is that none is documented and there is no operational reason why one would be needed, and so why would one have been added to the firmware? Invoking altitude symmetry around the takeoff as a reason to expect one makes no sense, since up is not equivalent to down in terms of the hazards it presents.
FWIW Litchi's minimum BGL is -200 m (Below Ground Level). Don't know about DJI FW and GO app.
Using The GO app I've had both the P3P and P4 at 185 ft. below takeoff point, with no issues, error messages, or anything out of the ordinary. The app displays height as a negative measurement.
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It is possible that they did not code for large negative numbers and the OP simply wishes to know if anything had been QA'd and can be empirically detailed.
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