Question about the 400 ft. rule

[draver]

I'm wondering if following the terrain at less than 400 feet is in compliance with the letter & spirit of the 400 ft. AGL rule for drones. If I choose to fly up a mountainside, say to a 2,500 foot summit at 300 ft. AGL, am I an outlaw? Also, in this discussion, if my Return To Home altitude is set for 30 meters Above Ground Level, will the drone hug the mountainside at 30 meters AGL returning to me? Or, will it suppose I meant 30 meters above it's launch altitude? Any support for your opinions would be appreciated.

 

[Gecko10]

I believe 400" Above the Ground means exactly 400" Above the Ground wherever you are, even if you are on Mt. Everest.

 

[IShouldBeWorking]

The scenario you describe sounds fine to me in theory. In practice, Mavics only calculate their 400 AGL from the home point. So, to scale a mountain like in your scenario, you'd have to land, reset your home point, climb 400 feet higher, land, then repeat. You would need to keep following that process over and over to get to the top of the mountain.

 

[ataraxia]

I believe 400" Above the Ground means exactly 400" Above the Ground wherever you are, even if you are on Mt. Everest.

This. Read the drone code.

 

[draver]

To clarify, I assume you mean wherever your drone happens to be, now where the operator is located? I see videos of drones flying over the edge of cliffs for astounding footage, however it would seem that they are immediately in violation if the drop is more than 400 feet.

 

[AeroJ]

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...

 

[draver]

I’m in Portland, Oregon, USA with a prominent mountain (Mt. Hood) nearby. It is over 11,000 feet in elevation and quite scenic. I suspect the summit is out of reach for my Pro Platinum, but it should make for some interesting footage once I have a little more experience.

I’m still very curious about how the DJI devices address RTH from heights above the preset. Is the RTH setting an Above Ground Level, or a fixed, absolute value?

 

[old man mavic]

in uk the 400ft ceiling is from the operator ie you flying the drone so if you were 200 ft up a 300 ft mountain you could fly 300 ft above the summit from where you are standing but if you were at the bottom of the mountain you could only fly 100 ft above the summit.
the return to home setting is where the mavic took off from the 30m return height would be from that point

 

[droneworx]

I’m in Portland, Oregon, USA with a prominent mountain (Mt. Hood) nearby. It is over 11,000 feet in elevation and quite scenic. I suspect the summit is out of reach for my Pro Platinum, but it should make for some interesting footage once I have a little more experience.

I’m still very curious about how the DJI devices address RTH from heights above the preset. Is the RTH setting an Above Ground Level, or an fixed, absolute value?

RTH is a set value above your current zero point. So if your current elevation is 500 feet, but its where you took off from and your drone shows 0, and your RTH is set to 100ft. it will rise to 600 feet (or 100 ft above your zero point) before returning home. RTH can be dangerous is alternating elevation terrains. The Rule of Thumb with RTH setting is to be higher than the tallest thing around you.

 

[IShouldBeWorking]

Is the RTH setting an Above Ground Level, or an fixed, absolute value?

The RTH altitude is a fixed value above the elevation recorded at the home point. So you want to make sure you set it high enough that you clear any obstacles (trees, ridges, Mt. Hood, whatever) when you fly back to that home point. And on a related note, I took my Mavic Pro to a work retreat near Mt. Hood a couple of summers ago and got some great footage. It's a beautiful area. You'll have lots of fun shooting there.

 

[zocalo]

To clarify, I assume you mean wherever your drone happens to be, now where the operator is located? I see videos of drones flying over the edge of cliffs for astounding footage, however it would seem that they are immediately in violation if the drop is more than 400 feet.

The CAA is pretty clear on this; any flight over 400ft AGL requires an exemption to be legal, and they don't make any automatic exceptions for going over a cliff edge. It's a 400ft vertical, not 400ft *from* the cliff.

However, camera angles can make cliffs seem a LOT taller than they are and 400ft cliffs in the UK are not all that common - The White Cliffs of Dover are 350ft, for instance. Other countries also have different rules, so that makes it entirely possible that at least some of the footage you've seen was obtained perfectly legally, and in practice even if you were (hypothetically speaking, obviously) to quickly pop over a sheer cliff over 400ft for some footage, the chances of a collision are slim as actual aircraft don't generally get too close to cliffs either. You can expect a world of hurt if you do have an accident though.

 

[zocalo]

The scenario you describe sounds fine to me in theory. In practice, Mavics only calculate their 400 AGL from the home point. So, to scale a mountain like in your scenario, you'd have to land, reset your home point, climb 400 feet higher, land, then repeat. You would need to keep following that process over and over to get to the top of the mountain.

Actually, you could change the max. ceiling setting in DJI Go to whatever you want upto 500m, you'd need to then manually ensure that your aircraft remained within AGL limits to have a legal flight. You could then "climb" the mountain in 500m vertical steps, rather than the default 120m ones. Some drones will also let you update your home point in-flight so provided you can keep up with the drone's ascent you could possibly even do it one flight. See the following video:

 

[AeroJ]

in uk the 400ft ceiling is from the operator ie you flying the drone so if you were 200 ft up a 300 ft mountain you could fly 300 ft above the summit from where you are standing but if you were at the bottom of the mountain you could only fly 100 ft above the summit.
the return to home setting is where the mavic took off from the 30m return height would be from that point

Sorry that is flat-out wrong The CAA have specifically advised it is AGL from where the craft is now. Operator / launch position has nothing to do with it, other than that (somewhat unhelpfully) it is what the craft is using to report your relative altitude to you.

 

[Mossiback]

... if my Return To Home altitude is set for 30 meters Above Ground Level, will the drone hug the mountainside at 30 meters AGL returning to me? Or, will it suppose I meant 30 meters above it's launch altitude?...

...I’m still very curious about how the DJI devices address RTH from heights above the preset. Is the RTH setting an Above Ground Level, or an fixed, absolute value?

If flying above the RTH height setting it will return at the current height.

 

[old man mavic]

sorry AeroJ you are correct the CAA changed it it was from the operator originally so now if the mountain was 300ft up high you could in fact be at 700ft if you were directly above thanks for your clarification

 

[packnrat]

legal: you can take off at your ground level. and only fly up to 400 above your head. BUT,,, if you are video a building, tower, etc. you are legal to fly 400 feet above that item.
no i am not a layer, no i did not sleep in a motels dirty bed last night. and internet advice is only worth what you paid for it.

 

[Asgard]

"The CAA is pretty clear on this; any flight over 400ft AGL requires an exemption to be legal"

Is it that simple
AeroJ

?, look at the image and wording on page 4 of CAP1687

Quote: the 400 ft height above the surface requirement may be interpreted as being a requirement to
remain within a 400 ft distance from the surface, as shown in the diagram below

400ft From the surface is not the same thing as 400ft AGL

 

[sar104]

"The CAA is pretty clear on this; any flight over 400ft AGL requires an exemption to be legal"

Is it that simple
AeroJ

?, look at the image and wording on page 4 of CAP1687

Quote: the 400 ft height above the surface requirement may be interpreted as being a requirement to
remain within a 400 ft distance from the surface, as shown in the diagram below

400ft From the surface is not the same thing as 400ft AGL

It's worth pointing out that this (shown below) is a different interpretation than the current AGL guidance in the US. Although it is broadly similar to the Part 107 400 ft rule in relation to structures, I don't think the FAA has ever mentioned it in relation to terrain.


CAP1687 July 2018

 

[Gecko10]

How can such a simple and plain rule get so convoluted in such a short time and turned into Rocket Science with Calculus requied to solve it.

 

[sar104]

How can such a simple and plain rule get so convoluted in such a short time and turned into Rocket Science with Calculus requied to solve it.

I don't know, but that sounds like a great idea. Everything is better with a bit of calculus and rocket science added.

 

[Simmo]

Think of the drone having a 400 ft length of string tied to it. That string must always touch the ground.

 

[Gecko10]

I don't know, but that sounds like a great idea. Everything is better with a bit of calculus and rocket science added.