Get more from your Mavic
The largest Mavic community in the world
Join Us Now

I thought I understood permissable flight altitude?

Mt-Ed

Member
Joined
Jul 16, 2020
Messages
16
Reaction score
3
Location
Helena, MT
Hello Zbip57. You have solved the mystery for me! I was right at the spot where you see the interstate "12" marker above Rimini, right in between those small yellow circles, and on the southern edge of the gray wedge. Those small yellow circles are the "landing strips" on private ranches. I was flying north from my position. I see that if I had flown south, I would have been flying outside of the gray wedge, instead of into it by flying north. I may have to try flying south and see what happens? I'm confused why this did not show up on B4Ufly, and it said I was good to fly? Can you please confirm for me, is "Mapbox" a flight clearance app? If it is, it is much much more through! I am so very happy that you educated me on this!!!! So much to learn.

On a side note, if you notice the rather small lake located approx. ENE, right at the edge of the outer yellow perimeter? There is an RC airfield located there. Those guys fly rather large (8'+ wingspans) RC planes there all the time, but I really don't think they ever come close to 400' (it's in the valley so no need). I'm going to go out there and see if my altitude is restricted there as well.
 

Mt-Ed

Member
Joined
Jul 16, 2020
Messages
16
Reaction score
3
Location
Helena, MT
Zbip57, where did you get that information on that map? I've looked everywhere I could imagine, and none of those resources have that detail? Thanks in advance!!
 

Zbip57

Well-Known Member
Joined
Apr 25, 2020
Messages
148
Reaction score
178
Location
Canada
Zbip57, where did you get that information on that map?
It's the DJI FlySafe GEO map. www.dji.com/ca/flysafe/geo-map

Below the map, be sure to check both the boxes next to Warning Zones and Enhanced Warning Zones to bring up more detail. It's useful for checking if DJI has any restrictions on the area you plan to fly in. Note that DJI's map is not necessarily accurate with respect to actual FAA restrictions or to any of the other B4UFly-type apps. But that online DJI map will very accurately tell where your DJI product will allow you to fly.

In your DJI Fly app, click twice on the map display (bottom left corner) to expand it fullscreen. Those GEO zones should all display on your app map.
 

Zbip57

Well-Known Member
Joined
Apr 25, 2020
Messages
148
Reaction score
178
Location
Canada
On a side note, if you notice the rather small lake located approx. ENE, right at the edge of the outer yellow perimeter? There is an RC airfield located there. Those guys fly rather large (8'+ wingspans) RC planes there all the time, but I really don't think they ever come close to 400' (it's in the valley so no need). I'm going to go out there and see if my altitude is restricted there as well.
Ah, I found it. This airport flight path height restriction is a DJI thing. It wouldn't affect any non-DJI products. Also note that the height restriction here is set to 150m (492 ft).

RC-Airfield.jpg

Check out more info about the DJI FlySafe GEO restrictions at www.dji.com/ca/flysafe/introduction

The altitude restrictions vary depending on the type of airport.

AirportZones.jpg
 

Mt-Ed

Member
Joined
Jul 16, 2020
Messages
16
Reaction score
3
Location
Helena, MT
Ah, I found it. This airport flight path height restriction is a DJI thing. It wouldn't affect any non-DJI products. Also note that the height restriction here is set to 150m (492 ft).

View attachment 109387

Check out more info about the DJI FlySafe GEO restrictions at www.dji.com/ca/flysafe/introduction

The altitude restrictions vary depending on the type of airport.

View attachment 109388
Your note of a max altitude of 492 ft reminded me that when I reviewed my flight logs, that was exactly the maximum altitude that I had achieved when flying the other day!!! This ads further validation to the why of what was happening with me the other day. Also, thanks very much for this additional information above.....very informative!!
 

DavidT_ NZ

Well-Known Member
Joined
Apr 30, 2020
Messages
184
Reaction score
188
Age
66
Location
Tauranga, New Zealand
Just curious: can you ascend a mountain by updating the Home Point when you near the 400’ ceiling? Even perhaps landing in stages, if the terrain is good, with no wind. As long as a visual is maintained on the drone’s location (maybe fitting a strobe) and comms are strong, then fly it back manually to where you have the RC. I have an Air 2 in NZ but have not seen a height restriction yet based on the HP elevation, only via Government lands/Airport/airspace limits.
 

Starz

Well-Known Member
Premium Pilot
Joined
Dec 26, 2016
Messages
3,556
Reaction score
2,516
Location
Arizona
You would need to power down, then power up the aircraft to reset the home point altitude reading.
 

FoxFlight2020

Member
Joined
May 4, 2020
Messages
6
Reaction score
8
Location
Omaha, NE
I was above 400' yesterday because I was going over a 200' tall building. I normally have my max altitude set to 120m in case I'm not paying attention but, in this case with the various shots over buildings, I had turned it up. If it is the altitude AGL that is the only issue then all that happens is that it warns you that you are 120m above the home point. If you are legal (which in this case it sounds like you were), then acknowledge and blow past it.
 

Mt-Ed

Member
Joined
Jul 16, 2020
Messages
16
Reaction score
3
Location
Helena, MT
Just curious: can you ascend a mountain by updating the Home Point when you near the 400’ ceiling? Even perhaps landing in stages, if the terrain is good, with no wind. As long as a visual is maintained on the drone’s location (maybe fitting a strobe) and comms are strong, then fly it back manually to where you have the RC. I have an Air 2 in NZ but have not seen a height restriction yet based on the HP elevation, only via Government lands/Airport/airspace limits.
I wondered the same thing! I plan to hike up to the tops of the mountains here, and then take off from there. I'll bet my new home point elevation will be zero, even though I'll be over 6000'! I understand DJIs good intentions in restricting flight in these areas, but in this specific area, I was flying out of a "bowl" with mountains all around. Other than a helicopter, no fixed wing plane would be coming in for a landing BELOW these mountains, but since DJI algorithm assumes all land surrounding an airport is as flat as a table, they restrict elevation, even though, in this case, I was still about 900' below the mountains!
 

vindibona1

Well-Known Member
Joined
Jun 21, 2020
Messages
253
Reaction score
158
Age
59
Location
Cook County Illinois via Mexico City
I'd like to ask the question with a different scenario so I have a better understanding. But first to recap the OP's issue... GL is at 4000 ft and we know that the rules allow to go 400' above the ground or tallest structure within 400' of the drone. I'm still a bit confused. If you have ground steadily rising, how would you convey to the software that allows/restricts the drone to readjust as the topography changes...

... But say you are GL is MSL and you're 100' away from a building that is roughly 60 stories or 600 feet high and you want to go straight up until you're at the top of the building. In this scenario the topography is constant and unchanging, so how to you tell the drone to ignore the 400' AGL ceiling because you can legally go to 1000'???
 

PhiliusFoggg

Well-Known Member
Joined
Jul 24, 2019
Messages
970
Reaction score
687
Age
49
@ Vindibona1 I am not sure if I understand you question correctly but perhaps this may help.
In 'normal' drone flights "height above sea level" does not enter into consideration unless the take off point is itself high above sea level. The concern about "height above sea level" stems from the 'thickness' of the air at high altitude and whether or not the air is thick enough for the drone to generate enough lift to fly properly.


The max height ceiling as set by the app and controller is an entirely different entity and is not AGL.
It is height above the home point and to increase that ceiling all you do is adjust the maximum height thing in the app. This works up to 500m above the home point. "500m" is an absoulte ceiling, above the home point, written into the software in the drone.

The abilitiy to increase the maximum height ceiling, above the home point, is the reason my mini inadvertently climbed to an RTH height of 875ft following a loss of signal. Having taken off from its base I wanted to fly up and over the top of a cliff, in order to get the necesary ground clearance I just shoved the maximum height ceiling WAY up there.
During a subsequent low level part of the same flight I wanted distance and increased the max distance limit, in so doing I think I must have accidentally touched and dragged the RTH ceiling up too. So, when connection was lost UP went my mini.
The RTH height can not exceed the flight's maximum height ceiling, if I had reset the maximum height ceiling for the latter part of the flight my mini could not have climbed to 875ft.

It appears that Mt_Ed's problem is was due to something completely different. They intially took off in, shall we say, unrestricted air space but then climbed into conflict with the boundary of a restricted, three dimensional corridor that was 'hanging' in the air above them. I think I have read somewhere what defines the height of the floor of that corridor but have forgotten where I read it and what the definition was
 

Zbip57

Well-Known Member
Joined
Apr 25, 2020
Messages
148
Reaction score
178
Location
Canada
we know that the rules allow to go 400' above the ground or tallest structure within 400' of the drone.
[...] you're 100' away from a building that is roughly 60 stories or 600 feet high and you want to go straight up until you're at the top of the building. In this scenario the topography is constant and unchanging, so how to you tell the drone to ignore the 400' AGL ceiling because you can legally go to 1000'???
As PhiliusFoggg described, you can configure your own app to any ceiling up to 500m (1640ft) max above the recorded Home Position. That's hardcoded into every DJI drone.

Your app may issue a warning if you reach the 400' FAA limit, but the DJI drone only measures that height relative to your recorded Home Position. It doesn't know anything about actual height above ground, unless you are flying low enough for the Visual Positioning System to be within range of the ground.

In your scenario you would configure your app to a ceiling limit of 1000' and, as long as you stay within a 400' radius of that 600' tall building, you're legal.

Just a side note, I don't know why they insist on doing stuff like this, Transport Canada went a different route. Here in Canada we have the same 400' height limit, But instead of an extra 400' height within a 400' radius, we're only allowed to clear tall buildings by an extra 100' within a 200' radius of the building. [ CARS 901.25 ]
 

Zbip57

Well-Known Member
Joined
Apr 25, 2020
Messages
148
Reaction score
178
Location
Canada
It appears that Mt_Ed's problem is was due to something completely different. They initially took off in, shall we say, unrestricted air space but then climbed into conflict with the boundary of a restricted, three dimensional corridor that was 'hanging' in the air above them. I think I have read somewhere what defines the height of the floor of that corridor but have forgotten where I read it and what the definition was.
It's in post #24, right here.
 

Zbip57

Well-Known Member
Joined
Apr 25, 2020
Messages
148
Reaction score
178
Location
Canada
Sorry but either I am blind or I didn't explain myself very well, the floor of the corridor is set at a height 60m / 150m relative to what? Thanks
Ah, gotcha. Ideally it should be referenced with respect to the runway being zero height. But the drone only knows its own height relative to its recorded Home Position at takeoff.

Hopefully there wouldn't be a hilltop 150m high right off the end of the runway. But if you launched your drone from that hilltop, the DJI system would let you climb another 60m / 150 m (depending on how far from the end of the runway) before triggering the GEO Zone height restriction. The floor slopes upward from the end of the runway at an 8.5° angle.

Their FLySafe GEO system isn't perfect by far. But it's much improved over what it used to be. At least now they have more sensible height restrictions in line with active runways, rather than an unrealistic huge circle around airports.
 

PhiliusFoggg

Well-Known Member
Joined
Jul 24, 2019
Messages
970
Reaction score
687
Age
49
That's actually a bit scary, ....though I suspect the chance of it happening is pretty slim, a drone pilot could enter the corridor whilst believing that they were below it, 'all' safe and legal.
 
DJI Mavic Mounts
All E RC Mavic Drones

New Threads

Forum statistics

Threads
90,032
Messages
1,036,991
Members
118,384
Latest member
JohnDRhodes