Altitude over changing terrain

[BumblerBee]

Local Norwegian regulations dictate that the flight altitude should not exceed 120m above ground. So the obvious answer is to set max altitude to 120m and it should work - in a country with a relatively flat terrain, which Norway is famous for NOT having.

You can take at one point climb to 120 meters, fly 200 meters sideways and find yourself 10 meters over ground staring at a tree. Or you can take off at another spot, ascend by meagre 10 meters, fly a bit sideways and find yourself 150 meters over ground, thus breaking the regulations.

What's the best way to avoid such situations and would it be feasible for Mavic to have some kind of altitude over ground vs altitude over sea metering?

 

[Flycaster]

Terrain Follow in Flight modes?

 

[RaRaRasputin]

Mavic's height is calculated from take-off point

 

[BumblerBee]

That does not cover the second scenario, and it does not work when you are at 100+ meters up.

 

[Flycaster]

True, but I believe there is a terrain follow mode in the flight modes page. I haven't used it, but I think it won't go over 15 meters up, for the ground sensors to read????

 

[BumblerBee]

How do small planes, like Cessnas display their altitude to the pilots?

From the replies, it seems the only option is to know the terrain your are flying in and to keep your eyes open, right?

 

[Flycaster]

No matter what type of flight/flight mode you are doing, you have to keep alert and aware of what your craft is doing and headed, and surrounding "obstacles".
Try starting here:
terrain follow mavic - YouTube

 

[BumblerBee]

Thanks, I already experimented with the terrain follow mode, and it's fine for short low-altitide fights.

I am more concerned about the second case. Yesterday I was doing flights from a coast and out to sea to take some footage of the coast line. After take off, I kept to below 100m on the off-chance that the coast height from where I was taking off was already 20m above sea level, thus my altitude over water would be below 120m. If the coast were higher than that, then I would actually be flying above the allowed limit.

It would be nice to have a barometric altitude reading from the Mavic RC, in addition to the 0-meter take-off altitude.

 

[Plawa]

Not sure about Norway but the FAA regulations actually specify a sort of hemisphere in which you can fly... so if you take off from a 500ft tall building you can fly 400 ft sideways and still be considered at 0' AGL... at least that's my understanding, look into the details of your local regulations..

https://www.faa.gov/uas/media/Part_107_Summary.pdf
Maximum altitude of 400 feet above ground level (AGL) or, if higher than 400 feet AGL, remain within 400 feet of a structure.

 

[tcope]

Best way.... look at the drone and then the ground under it. Does it look to be 120m or less? If so, you are fine.

If you cannot tell the difference, what is the chance that an authority figure will come up beside you right at that second and know any better. The law was meant to apply to people that are _obviously_ well above 120m, not close.

 

[Path Finder]

Yes, I also wish the Mavic could tell us the distance above ground where it is at, not just where it took off from. Not the end of the world here in MN but want to take it into the mountains out west, seems life could get "interesting" out there not knowing the distance to the ground.

 

[tcope]

Yes, I also wish the Mavic could tell us the distance above ground where it is at, not just where it took off from. Not the end of the world here in MN but want to take it into the mountains out west, seems life could get "interesting" out there not knowing the distance to the ground.

Personally, I point the camera slightly down and fly the Mavic forward. between my visual of what's in front of the drone and the collision sensors, it's not much of an issue.

 

[BumblerBee]

Local Norwegian regulation state explicitly max height of 120m above sea or ground. Which means that if you take off at 20m above sea level, climb to 120m do a few passes over the coast (within limits) and then head out over the fjord, then you suddenly break the regulation by 20 meters and must remember to descend to 100m of RC-reported altitude.

Another situation that I already experience was this: I have a mountainous lake nearby, its surface level is 25m according to Google Earth, the shores are 30m. The best spot to take off is from the foot of the hill at 3m above sea level. Meaning that 120m from my take off stop translates into 65 meters over ground level when I fly above the lake shore. In other words, I want to cap DJI Go app max altitude at 175 meters to still be 120m above the shore for a vista shot.

Incidentally, inputting anything above 121m brings a warning in the app, saying that take responsibility fro breaking the regulations, even though the whole flight will be within the regulated maximum altitude of 120m above ground level.

I understand that this math still needs to be performed, but much of it would be simplified if the app reported the barometric altitude over sea level in addition to the reference take-off altitude.

 

[tcope]

I understand that this math still needs to be performed, but much of it would be simplified if the app reported the barometric altitude over sea level in addition to the reference take-off altitude.

Altitude over sea level would not help as it still would not tell you how high above the groud the drone was currently. The only way this all works is if the drone reports it's altitude above the ground currently under it. I'm sure this will happen eventually but right now that tech is simply not available to put in a drone.

As mentioned above, I really don't see this as an issue. You can see the drone, so you can certain guess as good as anyone how hight it is. I don't see that law enforcement is going to be standing behind you while you fly and guessing if you are at 119m or 121m. If you are at 400m and they came up, perhaps you might be cited. But you'd also know you are in violation at that point.

 

[Brojon]

Are they really going to come down on you for a few meters?
How would they determine you're out of bounds?

 

[tcope]

How would they determine you're out of bounds?

Measuring tape... and a really tall ladder.

 

[Plawa]

They're Vikings.. they're tall.