Height regulations when flying over a cliff?

[kjonyou]

So lets say I am at ground level at the edge of a restricted airspace. LAANCE says I can fly there up to 100 feet with approval. Standing at the edge of the cliff, there's a 100 foot drop to the ocean below and a small beach. What happens when I fly my drone over that edge? I am now 200 feet above sea level still in restricted air space, at what point am I breaking the law? Is there a gray area there?

 

[Phantomrain.org]

So yes to your question as far as I understand it once you fly over the cliff you have another 400 ft from the top of the cliff but you have to stay over the cliff to maintain it.

Phantomrain.org
Gear to fly in the Rain. Land on the Water.

 

[MAvic_South_Oz]

Since you're so knowledgeable, what keywords do you suggest? Maybe a link to a discussion would have been nicer?

A bit of a tough one, but > cliff edge altitude < seems to nail a few results.

Search results for query: Cliff edge altitude

mavicpilots.com

Personally, I feel restricted airspace of any kind would probably make a difference to my decision here in your scenario.
100’ AGL restriction is usually close to flight approach / departure areas.
Common sense if it’s possible any sort of aircraft could be within any sort of allowance from a cliifs edge by X distance.

 

[Phantomrain.org]

You always have to ask yourself if something were to happen would you be prosecuted to fullest extent of the law or would a court decide you were perfect in your thinking and actions ?

All the rules and regs are designed for when your sitting if front of the court. Thus Common Sense is #1 in my book as stated above.

 

[kjonyou]

I did an initial search, was not clear to me what the consensus was. Yes, common sense says the high limit gets lowered to where ground is, but what if for example a helicopter was buzzing along the cliff that low. I have seen a lot of them break that 500 foot limit rule to get a closer view of the coast line for example. One of the tracking apps I watch put them at 300 feet! If it ran into my drone, at what point is it my fault if I was trying to drop the altitude from above the cliff to the base of the cliff?

 

[MAvic_South_Oz]

One of the tracking apps I watch put them at 300 feet! If it ran into my drone, at what point is it my fault if I was trying to drop the altitude from above the cliff to the base of the cliff?

It would be a case of making sure flight is well within VLOS, even more so for somewhat restricted areas, and maybe keep within 50' or so of the cliff ?

The close VLOS thing is so if you hear something approaching, you are so close you can easily land. bring it closer to a safe place where even a heli wouldn't be flying (unless landing).

Then you'd have to watch things like LOS for signal if dropping down over the cliff edge, if signal was lost and RTH failsafe kicked in, it could send the aircraft up higher than you'd like over the lower canyon ground level.

All a bit hypothetical, but it is good to think about these scenarios.
Not very likely to ever cause you grief, miniscule risk you could say.
I know mitigating risk is the primary reason for airspace rules, but every single day you take a risk just getting out of bed, there is a line to trying to protect people.
Not easy to legislate for such things, just keep common sense, and yes, you'd think aircraft that are generally supposed to keep 500m AGL (except for special ops) would be right onto that and keep to a safer altitude.

 

[bmcelya]

I did an initial search, was not clear to me what the consensus was. Yes, common sense says the high limit gets lowered to where ground is, but what if for example a helicopter was buzzing along the cliff that low. I have seen a lot of them break that 500 foot limit rule to get a closer view of the coast line for example. One of the tracking apps I watch put them at 300 feet! If it ran into my drone, at what point is it my fault if I was trying to drop the altitude from above the cliff to the base of the cliff?

The FAA grants variances to tour aircraft in specific locations to fly below minimums. An example is Grand Canyon, where sightseeing helos and fixed wing are both allowed to fly outside normal minimums, along fixed routes . It would be a mistakes to assume that all helos flying below 500’ are in violation. Variance is also granted for power line maintenance and many other activities. If I hear/see a manned aircraft I hide behind a tree or something until it passes, because I can and they can’t.

When flying a manned aircraft, drones give me the willies. When flying drones, airplanes give me the willies. I like to drone where manned aircraft don’t go. Just picky that way. Not saying anyone else should.

 

[eEridani]

I did an initial search, was not clear to me what the consensus was. Yes, common sense says the high limit gets lowered to where ground is, but what if for example a helicopter was buzzing along the cliff that low. I have seen a lot of them break that 500 foot limit rule to get a closer view of the coast line for example. One of the tracking apps I watch put them at 300 feet! If it ran into my drone, at what point is it my fault if I was trying to drop the altitude from above the cliff to the base of the cliff?

As I read the rules, a drone operator must remain clear of private aircraft. So any collision is on the drone pilot.

 

[NativeAerialImagery]

Hello! I had a somewhat similar question that I asked Seattle TRACON directly regarding operations in rugged terrain and this was their response. "I don’t think you will need LAANC approval for most of these areas. LAANC is generally only necessary when you are operating within 5nm of an airport. Part 107 rules authorize you to operate in uncontrolled airspace at or below 400’ without additional authorization."

 

[Meta4]

I have seen a lot of them break that 500 foot limit rule

The assumption that there's a 500 ft limit isn't correct.
There are many situations where aircraft can legally fly below 500 ft.
Here's the actual rule.
Note C & D

§ 91.119 Minimum safe altitudes: General.​

Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:​

(a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.​

(b) Over congested areas. Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.​

(c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.​

(d) Helicopters, powered parachutes, and weight-shift-control aircraft. If the operation is conducted without hazard to persons or property on the surface—​

(1) A helicopter may be operated at less than the minimums prescribed in paragraph (b) or (c) of this section, provided each person operating the helicopter complies with any routes or altitudes specifically prescribed for helicopters by the FAA​

 

[HoozierDroneDaddy]

The subject got changed after the 4 or 5th post. The original question was related to what is his legal height after going over the cliff. He had LAANC authorization for 100' at the top of the cliff, however, once he flew over the cliff he is now at 200' AGL while over the beach. He wanted to know if his LAANC is now adjusted to 200' while out past the cliff.
This is a question on LAANC approvals in controlled airspace. The 400' rule is written for where the drone is actually flying, not from where the pilot is standing. When flying within 400' of a structure, he normally would be able to stay at the AGL authorized above the top of that structure as long as he is within 400' of that structure. The OP is flying in controlled airspace and with a LAANC authorization so the above rule may or may not apply. Someone with more knowledge on this area can chime in.
When I had a Wide Area Authorization, it specifically stated the authorization could not be adjusted when a structure was involved and authorized altitudes were absolute.

 

[cheddar-man]

I have always been confused with question.
As the drone height measuring system is a barometer I presume max flying altitude is above sea level.
But then that doesn't gell when you go up a hill, or would one be breaking the law fling on a 500 foot hill??
I have an 800 ft hill near our village which I would like to fly from to take some shots of the village. Woulds the drone even take off from there?? I regularly fly my gliders from there.
All very confusing!

 

[Phantomrain.org]

I have always been confused with question.
As the drone height measuring system is a barometer I presume max flying altitude is above sea level.
But then that doesn't gell when you go up a hill, or would one be breaking the law fling on a 500 foot hill??
I have an 800 ft hill near our village which I would like to fly from to take some shots of the village. Woulds the drone even take off from there?? I regularly fly my gliders from there.
All very confusing!

Go to the top of the hill , and you can fly 400 ft high from the top of the hill once you start flying away from the hill your breaking the FAA rules.

Phantomrain.org
Gear to fly in the Rain. Land on the Water

 

[DoomMeister]

Go to the top of the hill , and you can fly 400 ft high from the top of the hill once you start flying away from the hill your breaking the FAA rules.

Phantomrain.org
Gear to fly in the Rain. Land on the Water

Hard to break FAA rules when flying in England. CAA rules I could go for.

@cheddar-man the altitude you see when flying is the height the aircraft above/below the takeoff point. You can legally fly 400 feet AGL which is the altitude between the aircraft and the ground directly below it. If you took off at the base of the hill and followed the terrain to the top, you could legally be at 1200 feet altitude.

 

[cheddar-man]

So it's NOT above sea level - barometric, it's above ground level.

So how does the barometer re calibrate itself as it works on air pressure, above sea level!!

I'll take it up there one day, fly at some random height, 100feet, and then take it off the hill and see what the height registers. I'm curious!

 

[DoomMeister]

The barometer on the aircraft zeros itself each time you takeoff. So the value you see is relative to your takeoff point. The barometer on the aircraft does not measure height above the ground or sea level, only relative to your takeoff point.

If you went to the top and launched and climbed to 100 feet that would be the altitude displayed in the app. If you stayed at that altitude and flew away from the hill you would still see 100 feet displayed, but you would actually be at an altitude greater than 100 feet above the ground directly below the aircraft.

 

[eEridani]

So it's NOT above sea level - barometric, it's above ground level.

So how does the barometer re calibrate itself as it works on air pressure, above sea level!!

I'll take it up there one day, fly at some random height, 100feet, and then take it off the hill and see what the height registers. I'm curious!

There is AGL - Above Ground Level; and MSL - Mean Sea Level. Most drone regulation altitude speak is AGL. Charts and such generally state MSL, with a few references to structures that are both MSL (AGL).

ps: Adding to DM's post, your altitude on your drone will show negative. E.g., fly off a 200' cliff and drop down to the beach and your drone will show -180' (minus 180' or however close to the sand you get).

 

[cheddar-man]

Thanks DM, very helpful answer, now I understand!
The barometer sets itself to zero every time it takes so it is above ground level from point of takeoff

 

[retiredNH]

It's interesting that we'd spend so much time dissecting the regs' portions for AGL, where some common sense might apply. Many laws and their implementing regs have ambiguities. For the serious stuff, courts wade in to provide some common sense in the form of legal precedents. Let's hope the interpretation of AGL never comes to that! I note too that folks that enforce the law (and enforceable regs usually have law behind them) have a good deal of discretion regarding enforcement, as anyone who's passed a police car going above the speed limit knows.

 

[retiredNH]

Thanks DM, very helpful answer, now I understand!
The barometer sets itself to zero every time it takes so it is above ground level from point of takeoff

I have an altimeter app on my smartphone. It uses barometric pressure from the nearest reporting (weather) station for calibration, and is pretty accurate - within feet mostly. For decades, you could buy hiking altimeters that you zero at a known point, usually the trailhead.
Nothing new in this part of drones. It's a mature technology.