Staying 400ft AGL practicalities

[SimonMW]

Just a point regarding the 400ft AGL rule in the UK. How are people staying compliant with this in practical terms in wildly undulating environments such as Scottish mountain regions? I am told that no matter what we cannot break this rule when AGL is measured directly vertically down from the aircraft. And that if we take off from a mountain ridge, we cannot fly to the sides of it otherwise we break this rule unless we follow the side contour of the mountain.

But since we do not have any real time AGL instrument, and judging it by eye is nigh on impossible, how can this rule be effectively followed in such environments?

 

[Mazz]

Planes must fly 500 ft up and 500 ft away from anything so if you are by a mountain ridge you technically have 500 ft buffer from the cliff face.

 

[SimonMW]

You'd think that, but I've had a bit of a disagreement with one guy who is an ex RAF pilot who I think is part of an NQE (one who I actually hold a lot of respect for. No, definitely NOT Euro-USC!) who disagrees and says that if I take off from the ridge I must remain at 400ft AGL relative to a vertical line from the UAV. I mentioned the 500ft aspect of real planes to him and he has said that they measure vertically, and the fact that this means that the plane would be flying much closer to the sloping face is irrelevant. Not sure who to believe. He quoted the CAA regulation and wording, which he takes to mean rigidly 400ft AGL at any given time measured vertically from the aircraft. He also mentioned that the CAA would have no intention of it being interpreted any other way because it wasn't their problem if we couldn't get decent shots effectively.

Interestingly Euro-USC think that it is 400ft AGL from the point of take off. There's also the problem of how we keep tabs on this since we have no real time AGL instrument.

This all came about because I wrote a, hopefully easy to understand article for white water kayakers who are starting to use drones more and more here Responsible Drone Flying - Unsponsored

 

[The Editor]

You'd think that, but I've had a bit of a disagreement with one guy who is an ex RAF pilot who I think is part of an NQE (one who I actually hold a lot of respect for. No, definitely NOT Euro-USC!) who disagrees and says that if I take off from the ridge I must remain at 400ft AGL relative to a vertical line from the UAV. I mentioned the 500ft aspect of real planes to him and he has said that they measure vertically, and the fact that this means that the plane would be flying much closer to the sloping face is irrelevant. Not sure who to believe. He quoted the CAA regulation and wording, which he takes to mean rigidly 400ft AGL at any given time measured vertically from the aircraft. He also mentioned that the CAA would have no intention of it being interpreted any other way because it wasn't their problem if we couldn't get decent shots effectively.

Interestingly Euro-USC think that it is 400ft AGL from the point of take off. There's also the problem of how we keep tabs on this since we have no real time AGL instrument.

This all came about because I wrote a, hopefully easy to understand article for white water kayakers who are starting to use drones more and more here Responsible Drone Flying - Unsponsored

I do not think there is any ambiguity really - 400ft AGL is 400ft AGL. Drop a plumbline straight down vertically from the aircraft and you are allowed 400ft from the surface of the ground below. That's it.

Definition: Quote - "In aviation, atmospheric sciences and broadcasting, a height above ground level is a height measured with respect to the underlying ground surface"

 

[SimonMW]

Ok yes, that's fine. But the lack of practicalities means that it is a pretty unworkable definition in hilly/mountainous environments. I can think of a number of works produced by experienced people with PFAWs which would be rendered illegal if followed strictly. Plus it doesn't answer how we can know how far vertically we are at any given point? As I mentioned, we don't have an AGL indicator.

In other words, what good are rules and laws if they are impractical to follow in application?

 

[Mazz]

Completely agree with the guy. As the laws put it, it is measured vertically and once it drops off you are way higher than you should be. That being said, I was saying you have a safety buffer, not that what you are doing is fully legal. If you fly out 20-30 feet passed a cliffs edge I think, as far as practicality goes, you are safe. On top of that, if anyone ever opposed this you would have a pretty good argument.

 

[RaptorMan]

Planes must fly 500 ft up and 500 ft away from anything so if you are by a mountain ridge you technically have 500 ft buffer from the cliff face.

I was hiking in a canyon in Utah some years ago, to a place known as the White Ghost's or the Wahweap Hoodoos and a large private aircraft, probably 6-8 seats, fly's down the middle of the canyon at just about the height of the upper canyon tops or about 150 feet above the canyon floor. Later that day, maybe an hour later, a helicopter landed not far from the famed hoodoos.

I'm pretty sure the helicopter wasn't permitted to land there and I know the aircraft wasn't supposed to be that low.


Brian

 

[licensed pilot]

As a licensed pilot, I assure you there are plenty of stupid people flying airplanes (a large number of general aviation fatalities are pilot error); perhaps with education and training we can minimize acts of stupidity among UAV flyers.

 

[licensed pilot]

Ok yes, that's fine. But the lack of practicalities means that it is a pretty unworkable definition in hilly/mountainous environments. I can think of a number of works produced by experienced people with PFAWs which would be rendered illegal if followed strictly. Plus it doesn't answer how we can know how far vertically we are at any given point? As I mentioned, we don't have an AGL indicator.

In other words, what good are rules and laws if they are impractical to follow in application?

It is practically impossible to be a manned aircraft pilot for any amount of years w/o unintentionally violating some rule. The point should be that we should always try to be safe.

 

[Droneworx]

The CAA would look at it like 400' from the surface directly below the UAV. Now, if you were in a mountainous / hilly area and filming I highly doubt anyone will be reported in the UK for being slightly in breach of this. Firstly you'd need to piss off someone close-by and then they would report you to the police, then the police would need to decide to prosecute you on the evidence presented and then the CAA would assist if they feel the case is good enough. Believe me the CAA is having a hard enough time working on the pfaw issuance right now never mind having to prosecute anyone who flies a drone up a hill. They don't want people flying over congested areas (towns/built up areas/roads).

Oh and as stated above, the 400' rule is agl so directly beneath the UAV. Normal aircraft in the UK have a minimum of 500' from persons, vehicles, vessels and structures, unless for the purposes of take off and landing although that may now have been revised to say 'in accordance with good aviation practice'

Now, look at the angle of the hill. If you drew a line out to 400' from the surface perpendicular to the slope and it was 400' or less my feeling is that as long as you didn't go further than 400' away then there's not a chance you'd ever be prosecuted for that.

My advice is if you are flying in the hills in UK then just be sensible and don't go sending the uav on a 2 mile excursion away from you and I don't think you'd have any problems. Just use common sense.

(I have a reasonably good handle on the rules as 22 yr commercial/offshore and VIP helicopter pilot.)

 

[PrimeMotivator]

Does anyone make a super light laser alti that could fit on the back of an Inspire and transmit the data back to ground? Or perhaps it could be integrated into the go app using your GPS altitude, barometer and the altitude of the ground at the location of the aircraft from terrain maps.

 

[Droneworx]

The laser would need to be moveable to point towards the nearest surface so not really a viable option.

 

[RaptorMan]

Yeah, a laser is not the best choice for measuring AGL distance given the pitching and rolling a drone does and that's why radar is preferred. They make radar in very small packages these days and I expect we'll see that being the tech that dominates for full autonomous drones and then see that trickle down to consumer drones.

Millimeter wave radar will be useful for ground detection as well as collision avoidance. In addition, high frequency SAR could be used both as a radar altimeter as well as a ground imaging system.


Brian

 

[Paul]

I have been given permission to land and take-off from a private golf club. The airspace above the course is classified as uncontrolled. The course is rural and very hilly. Fortunately, this incident happened when I was NOT flying my S1000+. We were on the 3rd hole when we spotted a Police Helicopter fly up the valley, bank left and fly over our heads at a maximum altitude of 70ft AGL when he passed us.
Previously I had flown in the exact same spot with my Inspire at approx the same altitude. The consequences of what could of happened are all too clear. Who would have been at fault?? I suspect it would have been me in the dark room with electrodes attached to my sensitive areas not the helicopter pilot. Headlines - "Drone Downs Police Helicopter"

 

[PrimeMotivator]

Do you have anything in your ops manual about emergency evasive manoeuvres? Would there have been time to do anything?

 

[Paul]

If the flight had been a commercial operation and an observer was present and had seen the helicopter coming, possibly. But really flying at that low altitude ain't good.

 

[The Editor]

I have been given permission to land and take-off from a private golf club. The airspace above the course is classified as uncontrolled. The course is rural and very hilly. Fortunately, this incident happened when I was NOT flying my S1000+. We were on the 3rd hole when we spotted a Police Helicopter fly up the valley, bank left and fly over our heads at a maximum altitude of 70ft AGL when he passed us.
Previously I had flown in the exact same spot with my Inspire at approx the same altitude. The consequences of what could of happened are all too clear. Who would have been at fault?? I suspect it would have been me in the dark room with electrodes attached to my sensitive areas not the helicopter pilot. Headlines - "Drone Downs Police Helicopter"

This is why flying BVLOS and a mile away etc is so dangerous. The operator has no situational awareness and no aural sense whilst flying. You will invariably hear an approaching aircraft before you actually see it giving you time to locate it in the sky and if necessary take evasive maneuvers. I have had this happen to me once but it was a Chinook helicopter and you can hear those things coming from miles away.
The things that have caught me out a couple of times when I have been flying solo is **** gliders - no matter how good your hearing you don't hear those things creeping up on you..

 

[PeterB]

I don't know about the Scottish Highlands but I fly in The Lake District and I have to share the airspace with the RAF who may fly as low as 250ft agl or 0ft agl for helicopters. This is in the valleys never mind the fell tops. Helicopters I would expect to hear in advance but even jet trainers I see only after they've passed.
In my ops manual I have stated that during 'normal' low flying hours I will limit my height to 50m agl (mixed units as I use metric in the Go app).
If I want to fly higher then I can contact the CAA at [email protected] giving full details of the planned flight, reason for the flight and a copy of the PfAW. 28 days notice needs to be given. However the person I spoke to said they understand the problems of planning in advance with respect to weather conditions and he was prepared to accept a 'window' of dates initially, the final date being confirmed once conditions were known. The CAA would then take a view on what action to take, possibly issuing a NOTAM or informing the RAF.
In my very early days of uav flying I had a similar conversation with the CAA about flying from fell tops but lost the details when I lost my laptop. As I recall it was suggested that I could apply for a NOTAM through the same office. The NOTAM would refer to the take off height and cover a 1 nautical mile radius. I understood that this would cover all the air space above and below the take off point.

 

[AndyD]

Hi all,
I'm based up in Northumberland and operate close to Newcastle airspace. I've managed to get a contact email and phone number so although I'm not obliged to contact them (I'm sub 7kg PFAW), I will send a courtesy email in a NOTAM format if I can plan a day or two in advance (I've phoned once on a short notice evening op).
I think as long as we can info a local airport, then any civil air traffic like police or air ambulance would be notified of our drone ops in the vicinity. Of course we have to give way to manned air traffic and most of it you can hear coming but I like the belt and braces of at least informing someone we're around.
I've had two microlights fly through a farm I was filming; heard then saw them so brought drone in; one of the micros flew about 100ft above the main farmhouse...
It would be nice if we had a contact number/email for airports or at least a common reporting inbox. I know there will be logistic problems but we probably need some kind of broadcast forum where we can say, "hey I'm around".

 

[licensed pilot]

Hi all,
I'm based up in Northumberland and operate close to Newcastle airspace. I've managed to get a contact email and phone number so although I'm not obliged to contact them (I'm sub 7kg PFAW), I will send a courtesy email in a NOTAM format if I can plan a day or two in advance (I've phoned once on a short notice evening op).
I think as long as we can info a local airport, then any civil air traffic like police or air ambulance would be notified of our drone ops in the vicinity. Of course we have to give way to manned air traffic and most of it you can hear coming but I like the belt and braces of at least informing someone we're around.
I've had two microlights fly through a farm I was filming; heard then saw them so brought drone in; one of the micros flew about 100ft above the main farmhouse...
It would be nice if we had a contact number/email for airports or at least a common reporting inbox. I know there will be logistic problems but we probably need some kind of broadcast forum where we can say, "hey I'm around".

Well played, Sir. I am in the USA and a commercial operator, if I know I will need to fly anywhere near an airfield or heliport I make an effort to notify the operators of my flight plan. I have the cell number of the chief pilot of the Airevac medical helicopter unit in my city and I promised him I would notify him of ANY flight anywhere near the hospital helipad. We, as unmanned aircraft operators, have the burden to make every effort to notify known helicopter operations to minimize risk.