Ok...no I didn't and no I haven't flown my P4pro off he edge either...yet.

So, here's my (probably dumb) question.

Can I fly my UAV over the edge of the Grand Canyon?  

If I have my P4's max altitude set at 400 feet (FAA restriction?) or 300 feet (Transport Canada's restriction) what happens to the drone when it flys over the edge of the grand canyon and recognizes that it is more than 5000ft above the ground?

I suppose the same question could be asked in reverse...if you were at the bottom of the canyon could you fly back up along the canyon wall?

I guess the answer lies in exactly how the GP recognizes how high up above the ground it actually is.

Anyhoo...thanks for endulging me with this question.

Can’t fly there, not allowed.

Grumpy D Posted at 2018-5-16 10:54
Can’t fly there, not allowed.

LOL...didn't know that.  However, the question remains.  If I fly off a cliff that is 1000 ft deep....what will happen? Drop 600 ft?

If the rangers get wind of an sUAS flying in that National Park......you won't have to worry about a fly away.

They will most likely ticket, confiscate, and or toss you in jail and fine you.    Really,  don't take off in a National Park.

Randy

rwynant V1 Posted at 2018-5-16 11:14
If the rangers get wind of an sUAS flying in that National Park......you won't have to worry about a fly away.

They will most likely ticket, confiscate, and or toss you in jail and fine you.    Really,  don't take off in a National Park.

I was using the Grand Canyon as an example....if I could edit it and change it to "A CLIFF" with a 1000ft drop off I would.  Question still stands.

and recognizes that it is more than 5000ft above the ground?
How would it recognise that?
It doesn't have any sensor that would tell it that.
What happens if a plane or helicopter flies from a high point and descends?
The same happens to your Phantom.

For your Phantom, the only height it knows is Home = zero.
Everything else is higher or lower than home.

Grand Canyon - as all National Parks in the US - is entirely off limits for drones.

Your 2nd question:
The drone records the take off place as 0 meters. If you fly over a cliff and let the drone go down
it will show you negative height. You can fly it down 1000m and bring it back up since you never exceeded
the height limit which you define in the app.

But if you walk down into the canyon and start the drone from there you cannot fly the drone up to the edge 1000m above.
Absolute height limit in the app is 500m.

BC NightOwl Posted at 2018-5-16 11:02
LOL...didn't know that.  However, the question remains.  If I fly off a cliff that is 1000 ft deep....what will happen? Drop 600 ft?

The 400 ft limit is 400 ft above the take off point. So if you took off from the top of a cliff and you flew 500 ft down your altitude would read -500ft.

Labroides Posted at 2018-5-16 11:17
and recognizes that it is more than 5000ft above the ground?
How would it recognise that?
It doesn't have any sensor that would tell it that.

Ahhhh...ok...didn't realize that is how the altitude sensors work.  I assumed the GPS had a hand in knowing the altitude of the drone.

I believe that the UAV determines altitude from it's take off location. So, if you went up to 400' AGL (above ground level) from that take off point and flew out over a cliff, it would just continue on at the altitude that it was flying. For example, you could take off from the roof of a building and the UAV would 'see' the top of the building as 0 feet. Then you could fly 400' above that. The display would probably ignore the change in ground level. I live in a flat area, but when I do go over uneven ground, the UAV doesn't change its altitude, nor do I notice any change in the display.

The problem would come in if you used an automated app (like Litchi). That app does use the terrain and adjusts the altitude based on it.  I haven't tested it (because a crash would be possible), but as you set out waypoints, the difference from the first waypoint  (lift off location (+/-) is shown.

I'll go ahead and say it, because others will soon, It's VERY important to learn where you can fly first. If you were to fly at the grand canyon (a national park), the fine would be hefty... very hefty.

Eric13 Posted at 2018-5-16 11:17
Grand Canyon - as all National Parks in the US - is entirely off limits for drones.

Your 2nd question:

Thank you....that makes complete sense.    

Never had intentions of flying over the grand canyon...was just an example of a "cliff" for the question.

BC NightOwl Posted at 2018-5-16 11:19
Ahhhh...ok...didn't realize that is how the altitude sensors work.  I assumed the GPS had a hand in knowing the altitude of the drone.

GPS is very inaccurate for altitude.
The Phantom uses a barometer for altitude ... just like planes do.

Its really bizarre why you can not fly drones in the grand canyon or National parks in the US, I know helicopters use a small part of the canyon on a regular basis and a few have crashed and not due to drone use   but its fine to hunt shoot and trap animals!
We have a lot of these stupid rule here also in the UK but the hunting trapping and shooting also is a no no for the most part

The problem with faa or for that matter any controling body is the height restriction in these kinds of circumstances.
Lets forget that its a national park for now and lets say you were allowed to fly there your altitude restriction is from ground level (AGL)
So if you fly over the edge from the top then you must imeadiatly descend to your agl limit for your country.
If you take of from the bottom then you can climb the hill but stay under your agl limit this is measured from your drone to the ground beneath it.
Now here is were it gets tricky if your flying beside a cliff for example you cannot fly to the top of the cliff if its above your agl limit the same can legally be said if your fly from the top of the cliff legally you shouldnt fly over the edge if said cliff is higher than your agl limit as the ground below your drone could now be way outside your altitude limit.
This topic has been the subject of a few debates and discussions and no the top of a building does not classify as ground at least not here in australia.

As others have stated aircraft software uses takeoff point as zero altitude.  This also affects  some intelligent flight modes such as waypoint mode which will not work if flying at negative altitude even if you are well above the ground. Also the altitude you set for RTH uses the altitude from take off point not ground, so if you are flying the reverse of your example taking off in the valley and flying "over" the cliff and then start RTH, aircraft will descend and crash into the ground.  Finally, FAA altitude limit is 400ft AGL, "above ground level"  not what controller display shows relative to take off.  So, if you are flying 200 ft above ground and then fly off 400 ft "cliff"  you will be violating FAA (and AMA) rules unless you descend.

Wow...thanks everyone.  This was a question keeping me awake at night.  No - No...not the Grand Canyon part....that I knew, it was a bad example.  Should have just said, "a cliff".  I guess, just to be safe, I should just turn off the height restriction setting if I'm flying near a steep drop off.  Would hate to have to hike down to retreive the drone.  

BC NightOwl Posted at 2018-5-16 16:55
Wow...thanks everyone.  This was a question keeping me awake at night.  No - No...not the Grand Canyon part....that I knew, it was a bad example.  Should have just said, "a cliff".  I guess, just to be safe, I should just turn off the height restriction setting if I'm flying near a steep drop off.  Would hate to have to hike down to retreive the drone.

No need to turn it off. If you fly over the edge of a cliff, the aircraft has no idea that it has happened. It only knows how high it is above its take off point, it cannot 'see' the bottom of the cliff below.

Any height limit you set is above launch point.
Flying beyond a cliff edge is irrelevant to that

And the idea that you can't fly beyond a cliff edge because of agl height restrictions is silly.  No plane is going to be flying close to a cliff.  They have horizontal separation rules to follow.

Labroides Posted at 2018-5-16 17:46
Any height limit you set is above launch point.
Flying beyond a cliff edge is irrelevant to that

I agree it would be silly.  There are a lot of UAV rules that just seem like overkill to me.  I get that it's important for us all to fly responsibly and with safety and privacy always the priority.

I'm hoping that the powers that be have all chosen to err on the side of caution and that eventually we'll settle with basic common sense regulations.

I mean, we're allowed to drive x-mph, x-kph strapped to a 3 ton missile called a car/truck...through school zones, through parks, on highways etc. We do so because there are rules, we have a license, and we are insured.

wataero Posted at 2018-5-16 16:47
As others have stated aircraft software uses takeoff point as zero altitude.  This also affects  some intelligent flight modes such as waypoint mode which will not work if flying at negative altitude even if you are well above the ground. Also the altitude you set for RTH uses the altitude from take off point not ground, so if you are flying the reverse of your example taking off in the valley and flying "over" the cliff and then start RTH, aircraft will descend and crash into the ground.  Finally, FAA altitude limit is 400ft AGL, "above ground level"  not what controller display shows relative to take off.  So, if you are flying 200 ft above ground and then fly off 400 ft "cliff"  you will be violating FAA (and AMA) rules unless you descend.

"flying "over" the cliff and then start RTH, aircraft will descend and crash into the ground."
I think you have to read what it does once more. If higher than the set RTH altitude it will hold height until over home point and then start descending. So yes if you have been flying over something and descended on the other side still being higher that RTH alt it might go wrong, but it would not be the ground it hits due to a descend.
I am not sure if the reverse track function performed on lost signal also would include vertical changes but i think it only back track horizontal positions, perhaps other can clear that part out.

Possibly you would loose the signal when going over the cliff and never get it to descend on the other side anyway.