Altitude

[dronerdave]

I realize the law says no higher than 400ft AGL, but there's a practical side to enforcement. If you're off by say 200ft because of encountering a hill not that far off, I can't see being penalized.

It's like going 5mph over speed limit to pass a slow or dangerous driver, or deviating +/- 5 mph from speed limit due to human error.

I feel that I can do whatever I want but if something goes wrong and there is proof it was in part due to not following the rules, it might put me in the hot seat. I don't really think it's much different than flying above 400' on flat ground. There are long distance fliers violating the VLOS law and they get away with it all the time. I just try to follow the new rules as closely as possible to cover my actions.

 

[dronerdave]

Maybe it's common sense?

 

[OnTheRopes]

It's fairly easy for me. I watch the quad and use the screen to stay above the tree line. My altitude height is set to the max altitude so I can travel up a slope and never climb above 100-200'AGL even if I've gone up the hill 800'.

Sometimes I use the home point altitude info if I want to capture video of a short hill top. I fly to the hilltop and drop to my (safe) video altitude I want to do the fly by at, then check the altitude. I can then back off and fly at the hilltop w/o fear of hitting it because I know its height in reference to the home point altitude. At a fast pace flying speed, skirting over the top of the hill at 20 feet or so is interesting video. Obviously I know the terrain and know if it will cause me to violate the 400' AGL rule. Since the FAA took the gray areas out of the rules I avoid tall sheer cliffs.

I think where people get confused is that hobby fliers must follow slightly different rules than 107 pilots. It's also different from country to country.

I really meant though if you are on top of a hill or part way up a hill and fly away from yourself, it is impossible to know your height above ground level?

 

[OnTheRopes]

You do realise that the Max Altitude limit is user-configurable up to 1640 feet?
You can set it to whatever you like.

It's called estimating.
And to help, you have a sensor that tells you how much higher than the launch point your drone is.
It's not really difficult at all.

Yes I am well aware of how to estimate, but estimates have a habit of being inaccurate (ask my builder ) Fly from a mountain top and tell me you can estimate to any degree of accuracy.

 

[Meta4]

Yes I am well aware of how to estimate, but estimates have a habit of being inaccurate (ask my builder ) Fly from a mountain top and tell me you can estimate to any degree of accuracy.

If you can't estimate with enough accuracy you shouldn't be flying.
But if you really feel you have a problem in that regard, add a safety margin to your estimates.

How do you think real plane pilots manage?
Most light aircraft have only their barometric altimeter calibrated to give heights relative to sea level.

 

[MAvic_South_Oz]

I really meant though if you are on top of a hill or part way up a hill and fly away from yourself, it is impossible to know your height above ground level?

Not really without a lot of pre flight planning.
It’s just your best estimate and common sense.
Pre planning more accurate altitude with topographic maps (paper or online) isn’t terribly practical for most drone operators, you just have to try your best to fly at an AGL altitude to whatever country’s airspace laws.
(Edit fixed typo.)

 

[OnTheRopes]

Not really without a lot of pre flight planning.
It’s just your best estimate and common sense.
Thanks manning more accurate altitude with topographic maps (paper or online) isn’t terribly practical for most drone operators, you just have to try your best to fly at an AGL altitude to whatever country’s airspace laws.

Indeed and that is what I do and am comfortable with it myself but the UK CAA rule is 400' from the nearest terrain rather than above it (as in the chart above) which makes it even harder to estimate of course. Just saying really rather than raising an issue.

 

[OnTheRopes]

If you can't estimate with enough accuracy you shouldn't be flying.
But if you really feel you have a problem in that regard, add a safety margin to your estimates.

How do you think real plane pilots manage?
Most light aircraft have only their barometric altimeter calibrated to give heights relative to sea level.

I don't have a problem with it. Merely highlighting the legality

 

[Meta4]

I don't have a problem with it. Merely highlighting the legality

Think about it.
The CAA aren't going to be out monitoring your flights with a long ladder and a long tape measure.
They would also rely on estimates.
They aren't going to be doing anyone for 25ft over a limit and are only going to respond when there's a real issue.
A little common sense helps a lot dealing with this stuff but it's usually in short supply when this topic comes up..
How often do you have to fly right on 400 feet anyway?
Rigid adherence to a strictly measured 400ft is not important since no-one is going to be measuring anyway.
Flying in a way that is not unsafe is what's important.

 

[DanMan32]

Not really without a lot of pre flight planning.
It’s just your best estimate and common sense.
Pre planning more accurate altitude with topographic maps (paper or online) isn’t terribly practical for most drone operators, you just have to try your best to fly at an AGL altitude to whatever country’s airspace laws.
(Edit fixed typo.)

That's pretty much what I was getting at with my last post.

 

[SxSmith]

wouldn't it be easy enough for the mfg's to add an altimeter so the drone always know it height above the ground. I mean come on my car gps know my altitude.

It has a barometric altimeter. Probably never going to have a radar altimeter.

 

[Not A Speck Of Cereal]

Just a further observation: stuff on the ground is really, really teeny when you're way up high. That's not very useful to me, which is to say that I'm mostly interested in photography, and the lens is very wide-angle on most of these AC (is on my M2P). I'll leave the curvature-of-the-earth photography to pressurized manned ACs and spacecraft.

Also note: there is an operational service ceiling (this is a sea-level altitude limit, regardless of home-point altitude), beyond which DJI does not guarantee the aircraft will fly. The M2P owners manual specifies 6000m (~3.7 miles).

Chris

 

[bobscheel53]

You might want to reconsider that.
No air safety authority anywhere has a rule relating to height above your launch point ... only how high you fly above the ground below it.
If that seems wrong, perhaps this hypothetical example will clarify it for you:

The 400 ft AGL is to provide separation from aircraft that should be not be coming that low unless they are landing, taking off, or have special permission.

 

[superstarpup]

The 400 ft AGL is to provide separation from aircraft that should be not be coming that low unless they are landing, taking off, or have special permission.

That’s not true. Just to clarify for non-pilots, no special permission is required for aircraft to operate below 400’, and if you are operating a drone you should expect and be prepared to encounter actual aircraft at any time, and at any altitude

 

[Not A Speck Of Cereal]

That’s not true. Just to clarify for non-pilots, no special permission is required for aircraft to operate below 400’, and if you are operating a drone you should expect and be prepared to encounter actual aircraft at any time, and at any altitude

Yeah, anyone that lives in an urban environment with helicopters around knows to keep their ears open and be prepared to DOWN STICK at any time — they're frequently below 400'.

And sometimes fixed-wing aircraft too. I live in a city with a lot of air harbors, and while that may seem to qualify for " landing, taking off", they do a lot of low flying before approach.

Chris

 

[Pommystuart]

Check this out.

You are a very game boy. I doubt I could see the drone at that distance.

 

[ajkm]

Two points that haven’t been raised - airspace, other aircraft.

So, even in Class G, you could have a Class E transition airspace above you with a floor at 700ft - so restricting the legal altitude to 400ft provides separation for safety.

If it’s Class at with no overlying Class E, then 400ft is regulated so as not to conflict with manned aircraft that have a minimum altitude at which they must fly.

So 400ft AGL means exactly that, 400ft above the ground. It’s not altitude ASL. So if you fly off a mountain from 2000ft ASL, you can go to 2400ft ASL (400ft AGL) but only vertically.

If you fly laterally off the mountain from 2000ft ASL you would need to descend from your take off point to keep the aircraft within 400ft AGL (ie of the actual ground, Irrespective of its height ASL).

The service ceiling of M2P is 19,000ft ASL but I can’t see why anyone would want to fly at that altitude.

 

[superstarpup]

If it’s Class at with no overlying Class E, then 400ft is regulated so as not to conflict with manned aircraft that have a minimum altitude at which they must fly.

What’s that minimum altitude?

 

[Thomas B]

What’s that minimum altitude?

500’ except in TO and landing

 

[Meta4]

The 400 ft AGL is to provide separation from aircraft that should be not be coming that low unless they are landing, taking off, or have special permission.

What’s that minimum altitude?

500’ except in TO and landing

Real life is not that simple.
Here are the actual FAA rules (other countries rules are usually similar)
Note particularly 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