Approaching Helicopter......?

[Crow Horse]

I had one incident with an approaching helicopter. I could hear it long before I could see it. I'm not sure if it had anything to do with terrain but even with sound it was very difficult to determine a precise direction because the sound seemed to echo off the surrounding buildings. When I finally did see it the helicopter was well away from the drone but that period of time between hearing it and seeing it was disconcerting.

Depending on the terrain, the same issue can occur in wooded areas. Sound can bounce off of various features and make determining it's true location difficult.

 

[zocalo]

You have to remember that altitude is safety to a pilot. No helicopter pilot will be flying at 400ft unless there is a definite reason to do so, searching, landing, or sightseeing. For getting from A to B they will always be up higher.

You'd hope so, but definitely not always. I live on a line of hills between two large valleys, just below the ridge line, and both helicopters and aircraft often fly over the ridge at well below 400ft rather than climb and descend, unless you call avoiding a bit of fuel consumption and undertaking a change of altitude a definite reason to do so. I've had to deconflict on multiple occassions now because of this, and on at least one occassion a helo has been low enough to spook my neighbour's cattle.

To be clear, it's not every pilot that does this, and light aircraft pilots do tend to be higher up more often than not, but what is very likely a small minority of our local helo pilots generally seem quite lax in their adherance to both minimum altitudes and proximity to residential properties requirements and we typically get a "fly past" like this every few weeks or so. Yes, it's a combination of laziness and flight efficiency, so I can understand why they might do it given the window of risk might seem pretty low, but I fly my drone here often, operating over quite a large area of pasture and moorland owned by myself and my neighbours, so the risk is probably a lot greater than they realise.

Frankly, I'm starting to think I need to try and safely capture some evidence of this behaviour and send it to the CAA, because I'm sure my experiences are not the only place this is happening. Drones are a well-established thing, can be flying legally pretty much anywhere outside of defined NFZs up to 400ft (your jurisdiction may vary), and illegally anywhere at all. IMHO, it's past time that there was a little bit more onus on light aircraft pilots to take this into account and be a little more circumspect about low altitude flying - ultimately, they've got a lot more on the line than we do.

 

[maelstrom]

I live on a line of hills between two large valleys, just below the ridge line, and both helicopters and aircraft often fly over the ridge at well below 400ft rather than climb and descend, unless you call avoiding a bit of fuel consumption and undertaking a change of altitude a definite reason to do so.

As you mentioned the CAA later in your post, I’m guessing that you live in the UK. The regulations say that:

“Low flying
In general, except when necessary for take-off or landing, an aircraft should be 1,000 ft over a built-up area or otherwise 500ft from people, vehicles, vessels and structures. Note that the legislation does not mention animals.”

So if the aircraft isn’t over a built-up area or within 500ft (150m - note this is a distance, not a height) of people, vehicles, vessels or structures, it can theoretically be below 400ft and remain within the regulations.

 

[Cymruflyer]

I would almost agree, except for the National Guard. They come over my neighborhood at lower than 200' all the time (at least twice a day). Granted, they're probably flying training missions, but they're still well below 200' at times and often times they don't have ADS-B enabled, so they aren't seen from public resources, that I've seen, at least.

Well of course the military can do whatever they want and have a completely different reason for doing so. My comments are always about GA and commercial flight.

 

[Cymruflyer]

I had one incident with an approaching helicopter. I could hear it long before I could see it. I'm not sure if it had anything to do with terrain but even with sound it was very difficult to determine a precise direction because the sound seemed to echo off the surrounding buildings. When I finally did see it the helicopter was well away from the drone but that period of time between hearing it and seeing it was disconcerting.

Building will throw you off as to the sound and direction of the helicopter. Another thing to consider is wind and its strength. If you are down wind of an approaching helicopter, you will hear it sooner than on a calm day and if it is a strong wind day (and you choose to fly your drone) and you are up wind of an approaching helicopter, you may not hear it until it is much closer, compared to the other two scenarios.

 

[EpicFlight]

Maybe I'm just an old, simple guy, but I just don't see the issue. I live and fly near a small active airport, Helis show up when I'm flying all the time.

I always hear it before I see it, and since I can see my drone, there's no possibility of a problem. Descend to 100' or so AGL until the heli passes, then carry on.

 

[Cymruflyer]

As you mentioned the CAA later in your post, I’m guessing that you live in the UK. The regulations say that:

“Low flying
In general, except when necessary for take-off or landing, an aircraft should be 1,000 ft over a built-up area or otherwise 500ft from people, vehicles, vessels and structures. Note that the legislation does not mention animals.”

So if the aircraft isn’t over a built-up area or within 500ft (150m - note this is a distance, not a height) of people, vehicles, vessels or structures, it can theoretically be below 400ft and remain within the regulations.

Quite correct, I'm from Wales and we often flew out on a day trip in a flight of 3-5 to somewhere in north Wales on the coast. Although we might be at a reasonable altitude over the valleys, we would some times fly over a mountain and the terrain below us would suddenly rise up of course. We did not bother to climb to maintain 1,500ft above the ground, we just flew a straight course.

When flying over such terrain you also have no idea if someone has built a house on the other side of a ridge just below the top. Therefore, a pilot may unintentionally fly right over that house on a trip somewhere. Seconds later that pilot would be well above the ground underneath them.

When I lived in Colorado, one dead calm late Autumn afternoon, I left Steam Boat Springs and headed home to Granby. I climbed to altitude to miss all the mountain peaks on my course and just settled in for the flight. Way off in the distance was once of those perfect textbook drawn mountains that went up perfectly to a nice sharp peak. It was dead ahead and kept watching it for quite a while as it did not seem to get closer. Then as I approached, it finally began to look like it was getting closer. Then it was speeding up a little as I plodded on. I was deciding whether I would need to add some throttle or just change course slightly to skirt around it.

I kept watching it and all of a sudden it came close very quickly, but I could easily determine I would be clearing it by about 50ft or so. As I mentioned it was one of those perfectly sharp pointed mountains that a child might draw, so it would be no trouble to just divert left or right around the peak. I stayed on course, and it just passed right underneath me and in an instant, I was 500 then 1,000ft above the ground again. It was a beautiful sight and feeling as that peak came right up to me. There was fresh snow on the peak and I could see the way the shrubbery on top had been wind blown to one side.

So yes, pilots do pass low over mountain or hill ridges from time to time, however, depending on wind conditions, passing low over a hillside ridge or worse a mountain ridge, things can quickly become dangerous, due to what the winds are doing over those ridges. Generally in the mountains you want to give yourself a minimum of 1,500ft over the highest point of that ridge to be safe from adverse effect from and wind present. Therefore, it is not very often that a pilot will choose to fly very low over a hill or mountain ridge.

And if anyone is flying their drone in such an area, if should be a piece of cake to just drop down to one side or the other of that ridge top to get out of the way. Therefore, there is no need to blow these scenarios all out of proportion. And again, I am not speaking of fighter pilot training or nape of the earth military helicopter training.

 

[nothingmemorable]

ADS B exchange loaded on a phone would give info on anything approaching

 

[EpicFlight]

ADS B exchange loaded on a phone would give info on anything approaching

While ADS-B is nice, my phone screen is not where my attention should be if I can hear a chopper.

 

[maelstrom]

ADS B exchange loaded on a phone would give info on anything approaching

Only if the approaching aircraft is using ADS-B! In Europe, for example, it’s not mandatory at the moment for aircraft below 5,700kg and not flying IFR to have it.

 

[zocalo]

As you mentioned the CAA later in your post, I’m guessing that you live in the UK. The regulations say that:

“Low flying
In general, except when necessary for take-off or landing, an aircraft should be 1,000 ft over a built-up area or otherwise 500ft from people, vehicles, vessels and structures. Note that the legislation does not mention animals.”

So if the aircraft isn’t over a built-up area or within 500ft (150m - note this is a distance, not a height) of people, vehicles, vessels or structures, it can theoretically be below 400ft and remain within the regulations.

Yeah, I know the regulations on this - I looked into them right after my first deconfliction because at the time I wasn't sure what the position was on AGL for light aircraft on brief terrain changes, i.e. whether it was similar to the "400ft distance" type restriction for drones or they had to maintain a minimum AGL vertically instead/as well. Turns out it depends on what's below, as your post indicates.

While it's undeniably a rural area, so the 500ft distance rule applies, there are several properties on both sides of the hills, mostly farmhouses with outbuildings, as well as a cell tower and wireless Internet repeater mast on the ridgeline above my property. The 500ft distance clause does give them some wiggle room and probably makes at least some of the incidents more likely to be legal, but there have also been occassions where they have definitely come within 500ft of properties and/or the two masts. Worst case incident, (my second deconfliction and the one that spooked the cows) I was at ~100m, having gone straight up from the driveway to get a 360-pano and some straight-down shots of the property, and I could see the approaching helo in the bottom half of my level viewfinder before I started my deconfliction descent. As far as I could tell, the pilot didn't climb at all, passed almost directly overhead, and presumably must therefore have cleared the ridgeline and cell tower by considerably than 100m since I'm about 30m below the ridge top.

In my view that means there is a very real, albeit slim, chance of a collision here, and if the aircraft is approaching from the far side of the ridge to me with the wind in the wrong direction, then there's a good chance I'm not going to have as much time to deconflict as I'd like either. On the upside, I'm now well aware of the possibility and take that into account whenever I fly, but that isn't bulletproof, and that's what concerns me. Drone pilots are expected to do their bit to be aware of other aircraft, but it seems that there are - hopefully a minority - of light aircraft pilots that perhaps don't feel that it's in their best interest to reciprocate and be aware of the potential for encountering someone flying a drone.

 

[Cymruflyer]

Yeah, I know the regulations on this - I looked into them right after my first deconfliction because at the time I wasn't sure what the position was on AGL for light aircraft on brief terrain changes, i.e. whether it was similar to the "400ft distance" type restriction for drones or they had to maintain a minimum AGL vertically instead/as well. Turns out it depends on what's below, as your post indicates.

While it's undeniably a rural area, so the 500ft distance rule applies, there are several properties on both sides of the hills, mostly farmhouses with outbuildings, as well as a cell tower and wireless Internet repeater mast on the ridgeline above my property. The 500ft distance clause does give them some wiggle room and probably makes at least some of the incidents more likely to be legal, but there have also been occassions where they have definitely come within 500ft of properties and/or the two masts. Worst case incident, (my second deconfliction and the one that spooked the cows) I was at ~100m, having gone straight up from the driveway to get a 360-pano and some straight-down shots of the property, and I could see the approaching helo in the bottom half of my level viewfinder before I started my deconfliction descent. As far as I could tell, the pilot didn't climb at all, passed almost directly overhead, and presumably must therefore have cleared the ridgeline and cell tower by considerably than 100m since I'm about 30m below the ridge top.

In my view that means there is a very real, albeit slim, chance of a collision here, and if the aircraft is approaching from the far side of the ridge to me with the wind in the wrong direction, then there's a good chance I'm not going to have as much time to deconflict as I'd like either. On the upside, I'm now well aware of the possibility and take that into account whenever I fly, but that isn't bulletproof, and that's what concerns me. Drone pilots are expected to do their bit to be aware of other aircraft, but it seems that there are - hopefully a minority - of light aircraft pilots that perhaps don't feel that it's in their best interest to reciprocate and be aware of the potential for encountering someone flying a drone.

It's nothing to do with that. Unfortunately you have never been up in a small plane because if you had been, you would see that a drone which is smaller than a hawk, will be next to impossible to see by a pilot in an aircraft, even if he had an idea of where to look. It's difficult enough to spot other aircraft, from time to time, especially when they are below the horizon sight level and mixed in with ground clutter, a drone would be a speck in comparison.

It is not a case of a pilot not caring but rather that it is just about impossible to spot. Go up on that ridge and see how many birds you can spot at a distance when they are mixed in with the background and then think about travelling at 100mph+ and you will understand. The next time you encounter one of these aircraft coming towards you, image your drone right next to it, as a size comparison and be truthful if you think you would be able to see that drone. Pilots are not keeping a lookout for drones, but rather, other aircraft and sometimes birds and they are extremely difficult to spot.

It might be a good idea for you to visit a local airport and ask for a 30 minute introductory flight because you are considering taking up flying lessons. Then see if you think you could spot a drone while up there in your restricted viewing space of a GA aircraft.

 

[zocalo]

It's nothing to do with that. Unfortunately you have never been up in a small plane because if you had been, you would see that a drone which is smaller than a hawk, will be next to impossible to see by a pilot in an aircraft, even if he had an idea of where to look. It's difficult enough to spot other aircraft, from time to time, especially when they are below the horizon sight level and mixed in with ground clutter, a drone would be a speck in comparison.

It is not a case of a pilot not caring but rather that it is just about impossible to spot. Go up on that ridge and see how many birds you can spot at a distance when they are mixed in with the background and then think about travelling at 100mph+ and you will understand. The next time you encounter one of these aircraft coming towards you, image your drone right next to it, as a size comparison and be truthful if you think you would be able to see that drone. Pilots are not keeping a lookout for drones, but rather, other aircraft and sometimes birds and they are extremely difficult to spot.

I've actually taken multiple flights in light aircraft, small jets, and helos, so I'm well aware that a drone would be almost impossible to spot from a moving manned aircraft, even a slow moving one like a glider or microlight - despite the claims of multiple airline pilots to the contrary. The point is more risk management and reduction, which pilots are meant to be all over, right? Special dispensations aside, the UK drone code is pretty clear that 400ft AGL/distance is the maximum permitted operating envelope for drones, and equivalent legislation elsewhere has similar rules. Apart from a few bad apples, that means that if you are flying an aircraft outside that envelope then your chances of sharing airspace with a drone is going to be vastly reduced and that there isn't really any need to even try and spot them - your biggest airborne threats are other aircraft and high-flying birds.

If a pilot is deliberately making a concious decision to clip a rise or peak and, as you pointed out in your 17:02 post, experience the thrill of a close flyby (which, I know from sightseeing flights, is definitely a rush), then that's a call they should also be accountable for. If that call results in a near miss, or worse, because someone was operating a drone and couldn't get out of the way in time, then my position is that they should have to take at least some of the responsibility for whatever comes after. To be clear though, I'm not suggesting there should be any changes to the requirement that drone pilot being the one that has to deconflict; even if we have full ADS-B integration or similar, the mere fact that drones can rapidly descend to a safe altitude makes that pretty much a given.

 

[Cymruflyer]

I've actually taken multiple flights in light aircraft, small jets, and helos, so I'm well aware that a drone would be almost impossible to spot from a moving manned aircraft, even a slow moving one like a glider or microlight - despite the claims of multiple airline pilots to the contrary. The point is more risk management and reduction, which pilots are meant to be all over, right? Special dispensations aside, the UK drone code is pretty clear that 400ft AGL/distance is the maximum permitted operating envelope for drones, and equivalent legislation elsewhere has similar rules. Apart from a few bad apples, that means that if you are flying an aircraft outside that envelope then your chances of sharing airspace with a drone is going to be vastly reduced and that there isn't really any need to even try and spot them - your biggest airborne threats are other aircraft and high-flying birds.

If a pilot is deliberately making a concious decision to clip a rise or peak and, as you pointed out in your 17:02 post, experience the thrill of a close flyby (which, I know from sightseeing flights, is definitely a rush), then that's a call they should also be accountable for. If that call results in a near miss, or worse, because someone was operating a drone and couldn't get out of the way in time, then my position is that they should have to take at least some of the responsibility for whatever comes after. To be clear though, I'm not suggesting there should be any changes to the requirement that drone pilot being the one that has to deconflict; even if we have full ADS-B integration or similar, the mere fact that drones can rapidly descend to a safe altitude makes that pretty much a given.

Drones are at the bottom of the totem pole so will always be at fault. If you have an encounter like you describe, you would hear the aircraft in plenty of time to drop down, so there should be no real chance of anything happening.

 

[BigAl07]

ADS B exchange loaded on a phone would give info on anything approaching

anything approaching? Negative... that's a very dangerous and false assumption.

Unless you're operating in Controlled Airspace its very UNWISE to assume every aircraft above/about you is broadcasting ADS-B. There are several LEGIT reasons why an aircraft would not be broadcasting. It's very foolish to blindly rely on an App/Program fully when it's only showing you a piece of the pie of the planes around you.