why 1400 ft max altitude?

[Chaosrider]

§107 rules do not apply to Recreational pilots. Those flying under USC 44809 are allowed to fly up to but not exceed 400’ AGL.

@akdrone DJI drones have a hard ceiling of 500m (1640 feet) above the takeoff point built into the firmware (or software). This means if you are flying along a 1400’ mountain you will only be able to clear it by 280’ if you take off from the base of the mountain.

@akdrone do not let people confuse you with rules that §107 pilots have to follow make sure you follow the rules set forth in USC 44809 the exemption for recreational pilots.

IIRC, the Rec rules are 400 ft ATO, not 400 ft AGL.

107 can fly 400 ft AGL.

MM

 

[Chaosrider]

Not just update the RTH location, but in order to reset the takeoff altitude, you've got to actually land and take off again. Theoretically possible, but perhaps challenging to find a flat spot halfway up the mountain where you can land while maintaining VLOS. And it's not just the VLOS rule you need to worry about, there's the practical matter of maintaining a good enough radio signal to take off after landing. Otherwise you may need to hike halfway up the mountain to retrieve your drone.

I've landed on my own home's roof and took off again, just to see how the altitude resets. It works.

I have a perfect test spot for this...Guardian Rock! It's about 600 ft ATO, about halfway up the other side of the canyon, where the ridge tops out at about 1200 ft ATO.

In theory, I can land on Guardian Rock, which would reset the take-off altitude, and then fly to 1643 ft ATO (new), which would be 2243 ft ATO (original).

I just don't have the...bluster...to try that. At least...not yet!



TCS

 

[Yorkshire_Pud]

Be warned, controlled descents from high flights can take a lllooonnnngggg time especially when you have stayed up there a little too long and are battery watching. It could be made even worse if you were distant and high and had to slow the horizontal return in order to lose enough height to remain inside the 400ft AGL layer.
I guess that is one reason DJI introduced the weird power saving RTH in one of the Air 2's?

 

[Zbip57]

I can land on Guardian Rock, which would reset the take-off altitude, and then fly to 1643 ft ATO (new), which would be 2243 ft ATO (original).

Be warned, controlled descents from high flights can take a lllooonnnngggg time...

Also, be aware that the smart RTH battery notification is based on the estimated time required to return to the recorded Home Position, i.e. Guardian Rock!

 

[Yorkshire_Pud]

Also, be aware that the smart RTH battery notification is based on the estimated time required to return to the recorded Home Position, i.e. Guardian Rock!

That's a very good point.
Isn't it wonderful how easy it is to overlook 'minor points' that could become critical? Though if I did a remote landing and take off I would reset the home point to the proper home as soon as the drone was airborne again and safely clear of the ground etc.

 

[Yorkshire_Pud]

Just a point and I have meant to ask this for a long time. Am I mistaken in thinking that that 'fancy' Air 2? RTH will, if applicable to the flight and used, always result in the drone breaking the 400ft AGL layer?

 

[MS Coast]

IIRC, the Rec rules are 400 ft ATO, not 400 ft AGL.

107 can fly 400 ft AGL.

MM

No, it's AGL.

49 U.S. Code § 44809 - Exception for limited recreational operations of unmanned aircraft

www.law.cornell.edu

(6) In Class G airspace, the aircraft is flown from the surface to not more than 400 feet above ground level and complies with all airspace restrictions and prohibitions.

 

[Rich QR]

No, it's AGL.

(6) In Class G airspace, the aircraft is flown from the surface to not more than 400 feet above ground level and complies with all airspace restrictions and prohibitions.

Correct. There is no airspace regulation in the US that defines the legality of flying through a particular bit of airspace based on the altitude of your takeoff point. Airspace altitude restrictions are always based on AGL, MSL, or FL. I believe altitude above takeoff point is never used in any regulation worldwide, though I certainly haven't studied the rules of every country, so I welcome correction. But if the intent of airspace regulations is to help keep traffic separated, it makes no sense to define an airspace and say say, "You are prohibited from flying here unless you originally took off from above <x> altitude." That would be equivalent to telling potentially conflicting traffic, "You're free to fly here, and you only need to look out for drones that took off from above <x>".

 

[DoomMeister]

So that's 400' above ground level, including a hill or mountain, correct?

An obstacle in this situation would be man made construction (cell tower, water tower, building, etc.) correct? So if flying up the incline of a mountain, it would still be okay, since you're 400' from the 'ground' of the mountain incline?

I honestly don't know and am curious.

Thanks,
Rob

Yes the 400’ AGL is above the ground as you follow the terrain. It does not include trees, cell towers, power lines, buildings, bridges, and the list goes on.

If it is part of the ground such as hills, mountains, natural rock piles, etc. then you can be up to 400’ above it and no more. Trees are not considered part of the ground.

This topic actually came up in another thread, and some thought that the exemption for recreational pilots used to allow the 400’ above when within 400’ of an obstruction. That has never been the case, and has only been allowed for §107 in Class G and Class E (except for E2 surface) airspace.

 

[DoomMeister]

IIRC, the Rec rules are 400 ft ATO, not 400 ft AGL.

107 can fly 400 ft AGL.

MM

Nope, it is 400’ AGL in Class G (uncontrolled airspace). In Controlled airspace it is limited to the height AGL that is specified in the clearance you obtain.

For AGL you measure straight down (not to the closest earth or water), so 49 USC 44809 pilots cannot legally fly up a sheer cliff more than 400’ above the base of that cliff.

 

[MAvic_South_Oz]

Just a point and I have meant to ask this for a long time. Am I mistaken in thinking that that 'fancy' Air 2? RTH will, if applicable to the flight and used, always result in the drone breaking the 400ft AGL layer?

Yes, if you have flown up a hillside / mountain following the terrain up, and the drone goes say to 600' above take off point, then even if RTH is set to 400', or 200' etc, it will stay at the height it is at when RTH begins.

So you'd need to keep the left stick down as it flies back in RTH mode, gradually dropping the height to suit APPROX 400' AGL as it returns.

It's kind of like a combination of auto and manual smart RTH on more modern DJI drones (the M3 only) where it takes a shorter route to home diagonally downward and back, rather than flying back same altitude then descending when over the home point.
Or, fly it home manually doing the same thing following the terrain back / downwards.

It's a good flight method to keep in mind and do on the flight back if a long way out, or fighting wind, and maybe getting worried about battery level.

 

[RH009]

Yes, if you have flown up a hillside / mountain following the terrain up, and the drone goes say to 600' above take off point, then even if RTH is set to 400', or 200' etc, it will stay at the height it is at when RTH begins.

So you'd need to keep the left stick down as it flies back in RTH mode, gradually dropping the height to suit APPROX 400' AGL as it returns.

It's kind of like a combination of auto and manual smart RTH on more modern DJI drones (the M3 only) where it takes a shorter route to home diagonally downward and back, rather than flying back same altitude then descending when over the home point.
Or, fly it home manually doing the same thing following the terrain back / downwards.

It's a good flight method to keep in mind and do on the flight back if a long way out, or fighting wind, and maybe getting worried about battery level.

That's fantastic to know, I didn't know that. I rarely use RTH because I usually fly it back, but it's good to know.

Rob

 

[Faster]

Yes, if you have flown up a hillside / mountain following the terrain up, and the drone goes say to 600' above take off point, then even if RTH is set to 400', or 200' etc, it will stay at the height it is at when RTH begins.

So you'd need to keep the left stick down as it flies back in RTH mode, gradually dropping the height to suit APPROX 400' AGL as it returns.

It's kind of like a combination of auto and manual smart RTH on more modern DJI drones (the M3 only) where it takes a shorter route to home diagonally downward and back, rather than flying back same altitude then descending when over the home point.
Or, fly it home manually doing the same thing following the terrain back / downwards.

It's a good flight method to keep in mind and do on the flight back if a long way out, or fighting wind, and maybe getting worried about battery level.

The Air 2S has something called Power Saving RTH that works similarly.

 

[MAvic_South_Oz]

The Air 2S has something called Power Saving RTH that works similarly.
View attachment 146265

Hey, thanks for the heads up, hadn't seen this commented on for any other aircraft until the new M3 came out with this type of feature.
It would certainly save some battery doing that, auto or manually activated RTH altitude from a hillside / mountain type flight scenario should certainly see a pilot drop as it returns, not only for keeping reasonably to the 400' AGL, but to save battery and keep out of higher winds.

 

[Yorkshire_Pud]

That's the one I was on about, as far as I can make out it leaves the drone well above 400ft over the home point every time, am I wrong?

 

[eEridani]

Correct. There is no airspace regulation in the US that defines the legality of flying through a particular bit of airspace based on the altitude of your takeoff point. Airspace altitude restrictions are always based on AGL, MSL, or FL. I believe altitude above takeoff point is never used in any regulation worldwide, though I certainly haven't studied the rules of every country, so I welcome correction. But if the intent of airspace regulations is to help keep traffic separated, it makes no sense to define an airspace and say say, "You are prohibited from flying here unless you originally took off from above <x> altitude." That would be equivalent to telling potentially conflicting traffic, "You're free to fly here, and you only need to look out for drones that took off from above <x>".

If I recall, calibrating the altimeter is always done to the airport you are approaching or leaving. Not quite what the discussion is about, but is one place where your wheels touch down matters. Helps keep the altitude of the patch stable.

 

[Zbip57]

Yes the 400’ AGL is above the ground as you follow the terrain. It does not include trees, cell towers, power lines, buildings, bridges, and the list goes on.

If it is part of the ground such as hills, mountains, natural rock piles, etc. then you can be up to 400’ above it and no more. Trees are not considered part of the ground.

This topic actually came up in another thread, and some thought that the exemption for recreational pilots used to allow the 400’ above when within 400’ of an obstruction. That has never been the case, and has only been allowed for §107 in Class G and Class E (except for E2 surface) airspace.

"Natural rock piles". What about unnatural man-made rock piles? One's natural, the other is a "structure"?

I do know that you are totally correct, because that is what the FAA regulations do say. I'm just still curious why anyone thinks this makes any sense. What purpose is served by such a distinction?

Isn't the intent to ensure safe separation between manned and unmanned aircraft? I don't know what the actual FAA requirements say for manned aircraft, but other than for landing/takeoff (and other exceptions like helicopters and cropdusters etc) aren't manned aircraft supposed to stay 500'(?) away, horizontally and vertically, from any "obstacle", not just ground. Obstacles include terrain, structures, towers, and even trees, no?

Flying over a dense forest, manned aircraft should probably stay at least 500' higher than the treetops, no? That distance wouldn't be measured from the ground's surface. It's not safe for manned aircraft to be skimming the tops of 500' tall trees, eh.

So if manned aircraft are supposed to stay that far away from any obstacle, why shouldn't drones be allowed to safely operate within that vacant airspace, no further than 400' from any obstacle (measured vertically and horizontally). Wouldn't that make more a whole lot more sense?

I do understand how this came to be. Originally the wording said something like, drones cannot ever be operated higher than 400' above ground. But then commercial drone pilots would be barred from using drones for tower inspections higher than 400'. So an allowance was made for "structure" inspections. But since inspections aren't allowed under Recreational flight, that extra height allowance only applies to Part 107 operations. Hence the resulting distinction between Recreational and Part 107.

But it still makes no sense.

If I'm allowed to conduct recreational flights an additional 400' over any natural obstacle made of earth or rock, why should it be any different if that obstacle is a tree, or a man-made obstacle composed not of earth but a hill of garbage in a landfill site, or any other man-made obstacle constructed of metal or concrete (structures)?

Manned aircraft still need to stay the same distance away horizontally and vertically from "structures", same as any other "obstacle".

I understand that it says what it says. I just don't understand WHY it should say what it does. If I can fly over a 400' hilltop, why can't I fly over a 400' tree? That's just silly.

 

[Rich QR]

"Natural rock piles". What about unnatural man-made rock piles? One's natural, the other is a "structure"?

I do know that you are totally correct, because that is what the FAA regulations do say. I'm just still curious why anyone thinks this makes any sense. What purpose is served by such a distinction?

Isn't the intent to ensure safe separation between manned and unmanned aircraft? I don't know what the actual FAA requirements say for manned aircraft, but other than for landing/takeoff (and other exceptions like helicopters and cropdusters etc) aren't manned aircraft supposed to stay 500'(?) away, horizontally and vertically, from any "obstacle", not just ground. Obstacles include terrain, structures, towers, and even trees, no?

The relevant rule is section 91.119. In particular 91.119(c) describes the restriction in "other than congested areas". It says that no person may operate an aircraft below "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."

A tree is not a person, vessel, vehicle, or structure. Nor is a natural rock pile.

Notice that, over open water or sparsely populated areas, there is no minimum altitude above the surface, as long as the aircraft maintains 500' distance from any person, vessel, vehicle, or structure. In areas that are not considered sparsely populated, the limit is 500' above the surface, not above the treetops.

 

[eEridani]

An example is landing; at some rural strips it isn't uncommon for trees or even powerlines at the ends of the aprons and you go as low as needed to ensure a safe landing. Similar is true for practicing emergency procedures: soft field engine out practice over farmland. Way back when I was doing a lot of this, I often wondered if the farmers ever got upset we were buzzing his fields - but we did try to spread the love around .

 

[DoomMeister]

"Natural rock piles". What about unnatural man-made rock piles? One's natural, the other is a "structure"?

I do know that you are totally correct, because that is what the FAA regulations do say. I'm just still curious why anyone thinks this makes any sense. What purpose is served by such a distinction?

Isn't the intent to ensure safe separation between manned and unmanned aircraft? I don't know what the actual FAA requirements say for manned aircraft, but other than for landing/takeoff (and other exceptions like helicopters and cropdusters etc) aren't manned aircraft supposed to stay 500'(?) away, horizontally and vertically, from any "obstacle", not just ground. Obstacles include terrain, structures, towers, and even trees, no?

Flying over a dense forest, manned aircraft should probably stay at least 500' higher than the treetops, no? That distance wouldn't be measured from the ground's surface. It's not safe for manned aircraft to be skimming the tops of 500' tall trees, eh.

So if manned aircraft are supposed to stay that far away from any obstacle, why shouldn't drones be allowed to safely operate within that vacant airspace, no further than 400' from any obstacle (measured vertically and horizontally). Wouldn't that make more a whole lot more sense?

I do understand how this came to be. Originally the wording said something like, drones cannot ever be operated higher than 400' above ground. But then commercial drone pilots would be barred from using drones for tower inspections higher than 400'. So an allowance was made for "structure" inspections. But since inspections aren't allowed under Recreational flight, that extra height allowance only applies to Part 107 operations. Hence the resulting distinction between Recreational and Part 107.

But it still makes no sense.

If I'm allowed to conduct recreational flights an additional 400' over any natural obstacle made of earth or rock, why should it be any different if that obstacle is a tree, or a man-made obstacle composed not of earth but a hill of garbage in a landfill site, or any other man-made obstacle constructed of metal or concrete (structures)?

Manned aircraft still need to stay the same distance away horizontally and vertically from "structures", same as any other "obstacle".

I understand that it says what it says. I just don't understand WHY it should say what it does. If I can fly over a 400' hilltop, why can't I fly over a 400' tree? That's just silly.

Don’t shoot the messenger, write to your Senators and Congressmen since they are the ones that wrote the rules.