Question about the 400 ft. rule

[sar104]

I always chuckle about the 500' rule below clouds. How do you measure that? A weather forecast?

TAF or METAR.

 

[Heyrob]

I always chuckle about the 500' rule below clouds. How do you measure that? A weather forecast?

I have to laugh at a lot of these rules!
I suppose it would be based on the closest METAR data.

 

[sar104]

Correct, I failed to qualify that. Hobbyists have a hard 400' ceiling, period.

No, they don't. If you think that they do, then perhaps you would like to cite the applicable law.

In a mere six posts on this forum you have managed to get two very simple elements of aviation law completely wrong.

 

[clydesur]

I was researching the same question before my flight. The top of the mountain is 1250 ft above takeoff point. The Mavic 2 maximum height is 1622 ft. keeping me less than 400 feet from ground at all times. Most of the flight was visual because the drone does not measure height from the ground but only from takeoff point. I must say it was nerve racking on the top when signal was lost. I was not sure how it would react although I knew it would return to home at the whatever height I was flying. Here is the video.

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[Rockowe]

Yep, it's 400 AGL if you're in the UK, so you can fly all the way up a mountain and then 400 ft above it, as long as you also decrease that altitude accordingly as you come back down...

The 400ft rule comes from BASIC Flying of Fixed wing aircraft. (Before anyone says anything I have a CPL - commercial)
… so this rule basically says - you may not fly lower than 500ft above ground unless on approach - (or takeoff)
… also Most helicopters are required to adhere to the minimum 500ft rule as well

Also Visual Flight rules VFR apply (with out getting into detail) - and Usually at this 500ft altitude, its considered OFF commercial radio and not in any controlled zones …. so you need to Blindly announce where you are.

So the 400ft Drone rule - Basically is designed that at no time - would it be possible that Larger aircraft and UAV's clash.

An aircraft Pilot would Fly Minimum above 500ft over a ridge - yet (pushing this rule) would be able to fly at 500ft through a Valley like Blyde river canyon - if VFR etc

Please note these rules are minimalistic - as larger aircraft are also guided by other rules (like a minimums over built up areas and a host of other... etc)

So back to drones...
... increasing altitude for a Mountain - or decreasing altitude - with a drone - if you took off from the mountain and fly down into the valley seems it would apply-

Maybe - - somebody could clarify more ...

 

[Broken Arrow]

I was researching the same question before my flight. The top of the mountain is 1250 ft above takeoff point. The Mavic 2 maximum height is 1622 ft. keeping me less than 400 feet from ground at all times. Most of the flight was visual because the drone does not measure height from the ground but only from takeoff point. I must say it was nerve racking on the top when signal was lost. I was not sure how it would react although I knew it would return to home at the whatever height I was flying. Here is the video.

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It was nice to see the Ghost Town Park again after all these years, went when I was a child. I parked in the lot at the end of your video about 12 - 14 years ago, I went to Tube World across the street, it was where the truck was climbing the hill. I took my 3 sons for a night of snow tubing down that hill. The object to the left was the "Magic Carpet"' a conveyor belt that hauled riders with tube to the top.

The Ghost Town was closed even then and rumored to be reopening, but at the time the investors who had purchased it also took responsibility of it's debt. Which included a law suit from a injury, possibly from that coaster? It was said then they had to many financial hurdles to open, maybe that has been resolved. Would be nice to go back and watch another gun fight out in the street at high noon.

 

[FlyGuy8675309]

so why is there a discussion about 400' LIMIT? if there is no limit?

The 400' "limit" in the US for recreational pilots is a "guideline", it's not a law (yet). I believe there's new laws coming down the pike... pretty sure a bill they passed this summer that will set a hard limit to 400' for rec flyers.

 

[wco81]

So the app. indicates you can set it up to 500 ft but when I tried, it wouldn't save that value.

Can you set it above 400 ft and fly above it or not?

My plan is to use it in some overseas destinations. Many of them have that same 400 ft limit but not all of them may.

 

[sar104]

So the app. indicates you can set it up to 500 ft but when I tried, it wouldn't save that value.

Can you set it above 400 ft and fly above it or not?

My plan is to use it in some overseas destinations. Many of them have that same 400 ft limit but not all of them may.

It's 500 meters, not feet, and it won't save the value unless the app is connected to the RC and the aircraft.

 

[Cymruflyer]

The 400 foot AGL makes sense in the respect, by limiting the drones to 400 permits for a 100 foot separation of fixed wing base. I am not a fixed wing pilot, but I did watch SKYKING when I was a kid! Truthfully, I have had several fixed wing friends inform me their base is 500. True or not, don’t know.

I assume you mean their base leg in the airport pattern. If that is what you mean then yes many use that altitude but it still has no effect on a drone pilot because the drone is not allowed to fly within 5 miles of the airport which means it will never even be close to a pattern of any in circuit landing aircraft.

 

[wco81]

It's 500 meters, not feet, and it won't save the value unless the app is connected to the RC and the aircraft.

Big difference.

Will check it out next time.

 

[MAvic_South_Oz]

So back to drones...
... increasing altitude for a Mountain - or decreasing altitude - with a drone - if you took off from the mountain and fly down into the valley seems it would apply-

You are asking ?
We have the 400' (120m) rule here in Australia.
I assume your 400' rule will be the same as ours when fully implemented.

If you fly form a peak and outwards over lower lying terrain, you must lower altitude of hte drone to keep to the 400' rule.
How on Earth can you do this correctly is open to question, there are ways, like furing up your drone at the valley floor etc, and getting altitude reading, then calculating the metres you need to descend as you fly.

Too time consuming and inaccurate ?
Possibly, but other than checking topographic map contours etc (actually Mapout app would be great for this) you would still be guessing to a certain degree on position on other mapping.

I guess being careful and estimating might be enough to keep authorities happy, if something were to happen or a flight be checked by someone when that tech arrives more widespread.

The 500m max setting was probably put there to allow the reverse within reason, climb as you ascend up a mountain side for example.
I'd guess they figured going 380m (1250') more in altitude is about all you can get from a drone in general before returning, at least so with many consumer drones.

 

[Cymruflyer]

I was researching the same question before my flight. The top of the mountain is 1250 ft above takeoff point. The Mavic 2 maximum height is 1622 ft. keeping me less than 400 feet from ground at all times. Most of the flight was visual because the drone does not measure height from the ground but only from takeoff point. I must say it was nerve racking on the top when signal was lost. I was not sure how it would react although I knew it would return to home at the whatever height I was flying. Here is the video.

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The pipes you wonder about running up the hill along side the lift and trail, are the water pipes many ski areas have to carry water up the hill side to supply the snow machines at set stations along the ski slope, for snow making when the temperature allows for that.

 

[sar104]

I assume you mean their base leg in the airport pattern. If that is what you mean then yes many use that altitude but it still has no effect on a drone pilot because the drone is not allowed to fly within 5 miles of the airport which means it will never even be close to a pattern of any in circuit landing aircraft.

That's not really correct - recreational pilots are just required to notify the airport and Part 107 pilots can fly anywhere in Class G airspace or in other classes with authorization.

 

[wco81]

Really 400 ft ceiling is absolute, not relative to take off and landing point?

 

[sar104]

Really 400 ft ceiling is absolute, not relative to take off and landing point?

Neither - the 400 ft limit (Part 107) or guideline (current recreational guidance) is above ground level (AGL), i.e. relative to the ground below the aircraft.

 

[Meta4]

Really 400 ft ceiling is absolute, not relative to take off and landing point?

It can only make sense for it to be relative to the ground below the aircraft.
Where you launch from makes no difference because the earth is not completely flat.

 

[wco81]

So does the controller display the AGL elevation?

Is it using barometric altimeter or GPS?

If I’m at the bottom of a sloping hill, I can fly along the slope at up to 400 ft above that slope.

I will be near sea level but I may fly to the top, let’s say at 500 ft and the done would be 400 ft above that so 900 ft above the pilot?

 

[sar104]

So does the controller display the AGL elevation?

Is it using barometric altimeter or GPS?

The controller does not display altitude AGL - it doesn't have a digital elevation model of the terrain from which to calculate it. It displays height above the takeoff point, estimated from the pressure reading from the barometer on the aircraft.

If I’m at the bottom of a sloping hill, I can fly along the slope at up to 400 ft above that slope.

I will be near sea level but I may fly to the top, let’s say at 500 ft and the done would be 400 ft above that so 900 ft above the pilot?

As long as the aircraft is no more than 400 ft above the ground below it then you are within the law/guideline. That could be thousands of feet above the takeoff point (VLOS permitting) if you have bypassed the 500 meter firmware restriction on all DJI drones.

 

[Simmo]

The RC displays height above Take off, so in your situation it would read 900ft yes. Totally legal.