Just read the >500 m thread and didn't want to threadjack...

[NetDep]

...but a question came to mind. My question is this: after viewing the video and the exact moment that the pilot sweeps over the vehicle and breaks the plane of the mesa - and over the valley below, is s/he in violation of the 400 AGL rule? Assume it is well beyond 400 AGL, which I think it is.

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I am interested since this is a place I would love to visit someday and the footage of the reveal or the slow pan over the vehicle and the breathtaking "wow" of the drop off I think. I certainly don't mean to aggravate anyone but am legitimately curious as to thoughts/opinions.

Thanks in advance and fly safe!!

 

[audi2000]

There is a lateral leeway, breaking the plane does not violate the rule. I believe it's 400' laterally also.

 

[FoxhallGH]

No - you are not in violation, as the 400ft rule allows you to ascend/descend that 400 ft hight cliff face, at a horizontal distance WITHIN 400 ft.
So if you were to start at the bottom, you can ascend 800 ft to put your drone 400 ft above & over the lip of the 400 ft + Mesa.
If you are dropping down over the lip of the Mesa, it doesn't matter how high the Mesa is, as long as you stay within 400 ft of the cliff face untill you are 400 ft from the ground - then you are OK ...
However - I'm a UK pilot and that's how it would work here, but from what I've seen in other posts, I think the 400ft limit applies to part 107 flights in the USA, and there is no height restriction placed on recreation flights [??] ... [Please feel free to correct if I'm wrong!] - but like everywhere - there is huge emphasis on keeping the Drone in Visual Line of sight ... That's going to be the challenge in the type of photograpy that you are looking to do.

 

[sar104]

...but a question came to mind. My question is this: after viewing the video and the exact moment that the pilot sweeps over the vehicle and breaks the plane of the mesa - and over the valley below, is s/he in violation of the 400 AGL rule? Assume it is well beyond 400 AGL, which I think it is.

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I am interested since this is a place I would love to visit someday and the footage of the reveal or the slow pan over the vehicle and the breathtaking "wow" of the drop off I think. I certainly don't mean to aggravate anyone but am legitimately curious as to thoughts/opinions.

Thanks in advance and fly safe!!

It's not addressed in US recreational rules at all. For Part 107 the requirement is 400 ft AGL or within 400 ft of a structure. It's not clarified whether a cliff face counts as a structure but it makes sense that it would, from the perspective of why the rule exists.

In the UK the requirement has been defined differently - it simply references distance to the terrain. That's harder to measure but makes the rule easier to apply.

 

[FoxhallGH]

It's not addressed in US recreational rules at all. For Part 107 the requirement is 400 ft AGL or within 400 ft of a structure. It's not clarified whether a cliff face counts as a structure but it makes sense that it would, from the perspective of why the rule exists.

In the UK the requirement has been defined differently - it simply references distance to the terrain. That's harder to measure but makes the rule easier to apply.

Yes - but we still have a lot of discussion going on as to how it's interpreted ... I put together the following diagram which illustrates the OP question from the point of keeping within a 400 ft (120 metre) boundary ... Hopefully that's helpful?

 

[sar104]

Yes - but we still have a lot of discussion going on as to how it's interpreted ... I put together the following diagram which illustrates the OP question from the point of keeping within a 400 ft (120 metre) boundary ... Hopefully that's helpful?

View attachment 60672

That's seems completely unambiguous. The CAA already produced their own similar graphic in CAP1687 last year:

 

[FoxhallGH]

100% agree with you and for me that's as plain as the nose etc. - but for some reason, there are still loads of questions going round (a string of them on my Facebook group recently) which reference this scenario - "Am I still flying legally if I fly out over the lip of a 600 ft cliff face?" ... There has been a 'helpful' tip bandied around recently that talks about imagining a 400 ft string hanging down from your drone, and that must always be touching the ground ... But that's not correct if you are flying off a slope ...
Some knowledge of basic trig' tells you that 'distance from the surface' is not the same as 'height above ground'!

 

[NetDep]

Thank you all so very much for the input - it is very helpful and really has clarified quite a bit. Sometimes we can be too close to a problem!! For clarification, I am in the US and a Part 107 holder although for purposes of something like that probably flying recreationally although who knows?!?

The diagrams helped and the notion of "lateral leeway" helps a lot as well. If I think of the end of the cliff as a building (for my purposes it makes good common sense) and I stay within 400' of it - I am good. The string attached to the drone is interesting and a nice way to visualize many of the rules in a more urban environ.

Certainly an exercise in what seems to be an often debated and rarely enforced set of circumstances.

Thank you again and fly safe!!!

 

[DanMan32]

100% agree with you and for me that's as plain as the nose etc. - but for some reason, there are still loads of questions going round (a string of them on my Facebook group recently) which reference this scenario - "Am I still flying legally if I fly out over the lip of a 600 ft cliff face?" ... There has been a 'helpful' tip bandied around recently that talks about imagining a 400 ft string hanging down from your drone, and that must always be touching the ground ... But that's not correct if you are flying off a slope ...
View attachment 60689 Some knowledge of basic trig' tells you that 'distance from the surface' is not the same as 'height above ground'!

That depends on definition of "surface" and "ground" and distance relationship.
To me, ground and surface are synonymous, meaning solid object directly below the AC rather than a perpendicular line from plane of solid object to AC.

 

[sar104]

That depends on definition of "surface" and "ground" and distance relationship.
To me, ground and surface are synonymous, meaning solid object directly below the AC rather than a perpendicular line from plane of solid object to AC.

The graphic above makes it completely clear what this means under UK law - which is defined neither as the vertical nor the perpendicular distance - it's the closest distance.

 

[paulatkin73]

Yes - but we still have a lot of discussion going on as to how it's interpreted ... I put together the following diagram which illustrates the OP question from the point of keeping within a 400 ft (120 metre) boundary ... Hopefully that's helpful?

View attachment 60672

BTW, just out of curiosity - when mavic goes now off the drop-off like that and previous, say, 30m altitude where optical path still works and it can measure where it is altitude wise - suddenly becomes, say, 730m - i understand it still ignores that as it does not enforce an actual distance to the surface? i mean, it is not going to drop down like a stone to the actual current 30m altitude after passing the drop-off edge? or will it?

 

[FoxhallGH]

BTW, just out of curiosity - when mavic goes now off the drop-off like that and previous, say, 30m altitude where optical path still works and it can measure where it is altitude wise - suddenly becomes, say, 730m - i understand it still ignores that as it does not enforce an actual distance to the surface? i mean, it is not going to drop down like a stone to the actual current 30m altitude after passing the drop-off edge? or will it?

No it won't because it's 'height' that is registered on the controller, and on Go 4, is 'relative' to the take-off point which the Drone registers (using a barometric sensor - I believe) as 'Zero' ... So if you took off and ascended 10 metres, the controller would register the 'height' at 10 metres - if you then flew out over the edge of a 200 metre cliff, the controller would still register the height as 10 metres. The optical sensors looking down from the Mavic are used to register the fact that there is a surface there, and to carry out 'Alitiude Hold' and landing functions - but they are not used to register the height of the drone above ground in regard to the info you see on your controller.
Another thing to note, is that if you do have 'Altitude Hold' enabled, it only works to keep the drone at a constant height above rising terrain - As soon as the terrain drops away, the drone maintains the current height along the course until the terrain is seen to rise again i.e. it's not like terrain avoidance in military aircraft ...

 

[FoxhallGH]

That depends on definition of "surface" and "ground" and distance relationship.
To me, ground and surface are synonymous, meaning solid object directly below the AC rather than a perpendicular line from plane of solid object to AC.

UK CAA have sought to make this point clearer (with various opinions on their success!) - and therefore while you are quite right in the way you think about it, the CAA have taken surface to include the vertical surface of a cliff face, so that this type of scenario is taken into account. If 'surface' was technically always directly under the drone, then ascents of vertical surfaces over 120 metres (400') would be impossible ...

 

[Meta4]

BTW, just out of curiosity - when mavic goes now off the drop-off like that and previous, say, 30m altitude where optical path still works and it can measure where it is altitude wise - suddenly becomes, say, 730m - i understand it still ignores that as it does not enforce an actual distance to the surface? i mean, it is not going to drop down like a stone to the actual current 30m altitude after passing the drop-off edge? or will it?

A couple of points that are important here:
1. The Mavic has no sensors that can tell it that it is 730 metres above the ground.
The VPS sensors have a range of 10 metres approx. Beyond that height they show nothing.
Check that next time you fly above 10 metres.
Your drone has no idea how far it is above the ground (except when the ground is closer than 10 metres)
2. Despite all the questions from nervous new flyers, your drone is not going to plunge to the bottom if you fly out over a cliff edge.
It's going to act just like any other bird or airplane that flies over a cliff edge.

 

[Phill]

No - you are not in violation, as the 400ft rule allows you to ascend/descend that 400 ft hight cliff face, at a horizontal distance WITHIN 400 ft.
So if you were to start at the bottom, you can ascend 800 ft to put your drone 400 ft above & over the lip of the 400 ft + Mesa.
If you are dropping down over the lip of the Mesa, it doesn't matter how high the Mesa is, as long as you stay within 400 ft of the cliff face untill you are 400 ft from the ground - then you are OK ...
However - I'm a UK pilot and that's how it would work here, but from what I've seen in other posts, I think the 400ft limit applies to part 107 flights in the USA, and there is no height restriction placed on recreation flights [??] ... [Please feel free to correct if I'm wrong!] - but like everywhere - there is huge emphasis on keeping the Drone in Visual Line of sight ... That's going to be the challenge in the type of photograpy that you are looking to do.

400 AGL down here in OZ but flying off a cliff does make you wonder.

 

[Meta4]

400 AGL down here in OZ but flying off a cliff does make you wonder.

Why?
The rules are brief and don't go into detail about each and every possible complicated scenario.
You have to use a little common sense.
Think the purpose of the rules - to keep drones from getting into airplane airspace.
How many airplanes are you going to encounter flying 100 feet out from a cliff face?
It's probably similar to the number of airspace inspectors you'll find with extra long ladders and jumbo tape measures while you're out there.

 

[paulatkin73]

Another thing to note, is that if you do have 'Altitude Hold' enabled, it only works to keep the drone at a constant height above rising terrain - As soon as the terrain drops away, the drone maintains the current height along the course until the terrain is seen to rise again i.e. it's not like terrain avoidance in military aircraft ...

I have a 40m good lidar-lite on the hex and within that range it follows the level of the ground, up or down. True, a 700m drop would produce out of range response from the lidar and its output will be ignored. Good to know that dji has a similar logic.

 

[Phill]

Why?
The rules are brief and don't go into detail about each and every possible complicated scenario.
You have to use a little common sense.
Think the purpose of the rules - to keep drones from getting into airplane airspace.
How many airplanes are you going to encounter flying 100 feet out from a cliff face?
It's probably similar to the number of airspace inspectors you'll find with extra long ladders and jumbo tape measures while you're out there.

You're right of course but I was wondering what an over zealous CASA inspector would make of it.

 

[kilomikebravo]

Another thing to note, is that if you do have 'Altitude Hold' enabled,

Foxhall: What "altitude hold" function"? News to me but that's no surprise.

 

[Spike151]

...but a question came to mind. My question is this: after viewing the video and the exact moment that the pilot sweeps over the vehicle and breaks the plane of the mesa - and over the valley below, is s/he in violation of the 400 AGL rule? Assume it is well beyond 400 AGL, which I think it is.

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I am interested since this is a place I would love to visit someday and the footage of the reveal or the slow pan over the vehicle and the breathtaking "wow" of the drop off I think. I certainly don't mean to aggravate anyone but am legitimately curious as to thoughts/opinions.

Thanks in advance and fly safe!!

I would say as the law is all about your intention, and the height AGL is about not colliding with other air traffic, in this video, would any light aircraft, helicopters, microlights, gliders be that close to the cliff face? I expect not, so as far as risk assessment goes, he could see vlos, he could also definitely see any other air vehicles coming close to the cliff face, at that location I expect there to be not a lot of background noise except wind, so he could hear anything coming he couldnt see that was under motor power.

For the drone laws, they are open to interpretation as any laws are, any court would ask " did he intend to cause harm, and did he take necessary steps to ensure he was flying safely. In my opinion he could answer no to the former and yes to the latter.