Many people think that helicopters can fly anywhere and do anything. After all, when you can take off and land vertically you should be able to go to just about any location, shouldn’t you? And since helicopters don’t stall at low airspeeds and can even come to a hover they really don’t have any limits when it comes to manoeuvring, do they?

Both these assumptions are wrong however. Although helicopters can indeed lift off and set down in this manner, it is not a particularly safe way of doing things. The problem with a vertical take-off is that if the engine fails you are unlikely to be able to land safely. When it all goes quiet in a helicopter you lower the collective, put the aircraft into autorotation and land. But you need altitude and/or forward airspeed to be able to do this effectively and if you are taking off vertically you don’t have either. As for landing somewhere directly beneath you, you need to be tremendously careful when doing this. The problem is that if you descend too fast with no airspeed and power applied you can get into a situation where the helicopter begins to fall down through its own downwash. This phenomenon is known as ‘vortex ring’ and it is about the only condition in which a helicopter can literally fall out of the sky. I’ve seen a video of it happening and it’s quite scary, to say the least!

One doesn’t operate a helicopter in this way therefore unless one absolutely has to. But of course, we have all seen helicopters acting in this manner, in news reports if nothing else, haven’t we? Yes, but helicopters used for things such as mountain rescue and emergency medical services are generally twin-engined and often have an autopilot or SAS (stability augmentation system) as well. This means that they can operate safely in the so-called ‘avoid curve’ (called, more graphically the ‘dead man’s curve’ in the USA) because they are far less likely to get into trouble. But most private pilots fly small single engine helicopters where they have to operate the controls manually all the time. Therefore this sort of flying isn’t really that safe.

Nevertheless many private helicopter pilots do fly within the avoid curve, some of the time. You learn to do so during the PPL(H) course and if you want to visit an hotel or restaurant for lunch, you may have to land on a fairly small helipad and it could mean a vertical let-down and a similar type of take-off. So long as they have the required amount of experience and skill, many pilots will take on this type of challenge. After all, they probably learned to fly helicopters partly in order to be able to do this sort of thing.

Helicopters don’t need airfields and runways; that is the main attraction of them for many of us and operating in this manner is not really likely to be dangerous. Engine failures are, thankfully, very rare in modern helicopters and you’d need to be extremely unlucky for one to occur just as you were approaching or leaving that hotel or restaurant. And vortex ring can be avoided so long as the pilot is very careful and lets down slowly so as not to have too fast a rate of descent.

[Pull out - Problems usually occur when other people who don’t know much about helicopters and their limitations want you to undertake a particular flight. The most common one is a photo sortie.]

Problems usually occur when other people who don’t know much about helicopters and their limitations want you to undertake a particular flight. The most common one is a photo sortie. A friend wants a photo of his or her house from the air and asks you to do the flight. It sounds really easy – you just fly over the house and your passenger will take the photos. You check and the area is outside controlled airspace and not in a congested area, so you agree.

The first difficulty often occurs when you start to try to find the house. People who are not used to flying always think that they will easily be able to recognise their house from the air but this if often not the case. I’ve lost count of the number of times I’ve tried to fly a trial lesson student to their home, only to be told: “But I don’t know which one it is”. My usual response to this is: “Well, sorry, but I don’t know where you live!”

However it’s when you actually identify the house that things start to become more complicated. Your passenger, keen to get some good photos and already impressed with the manoeuvrability of helicopters, starts to give you instructions. He wants you in exactly the right place. So it’s: “Can we go down a bit more; now left, a bit slower, hold it there.” You struggle to comply, since you offered to do this and you’d really like to make him happy, but it’s very easy to start concentrating too much on getting in the position required for that perfect shot and not enough on the actual flying. You become overloaded and you then forget that you’ve just turned downwind and while you still have some groundspeed, your airspeed is now zero. That is when if you just start to descend just a little without realising it you can get into vortex ring. It’s incredibly easy for this to occur and I had it happen once when we were doing some air-to-air photography for a magazine article. I recognised the early symptoms, as did the very experienced instructor who was flying with me, and incipient vortex ring is easy to correct if you recognise it in time – you simply push the cyclic forward and get some airspeed. So we were fine, but with less experience we might not have been.

Photographic flights are well known for this type of hazard but they are not the only time when you could get into this situation. It can occur any time when you are doing something new, flying slowly and running the risk of getting distracted. I remember a time when all of those were true and when an apparently simple – though unusual – type of flight turned into something far more challenging…

Several years ago I was a PPL(H), hour-building for my commercial licence. I lived in the mountains of North Wales and a developer had put in an application to erect a wind farm just above our beautiful valley. It was very close to several villages and some of us had formed an organisation to fight against this proposal. One of the most contentious issues was whether or not people would be able to see the proposed 300ft high wind turbines from the centres of population in the valley. According to the developers we would not, but we felt sure that they would be visible from practically everywhere. How to prove it? One of the group suggested a tethered balloon, but how would we get hold of one?  Then I had an idea. “I’m a helicopter pilot,” I said. “And I need the hours anyway.  I could fly over the site at 300 feet and you could note whether you can see me…and take photos.” So an idea was borne…

It sounded easy, but I quite quickly realised it wouldn’t be. First was how would I fly exactly 300 feet above a field on a hillside? I resolved this by looking at the 1:25,000 OS map to find the precise altitude of the field in question and setting the nearest regional QNH. It wouldn’t be exact, but it ought to be pretty close. I used the same map to identify the correct field. However, hovering at altitude is not such a good idea, for all the reasons mentioned previously. There were to be a number of wind turbines built so it ought to work if I simply orbited above the area in which they would be built. I asked my instructor about the plan and he agreed that it ought to be fine so long as I kept my airspeed above 30 knots, since you can’t get into vortex ring until you’re well below this speed.

So we did it. Alongside another member of the group, who had offered to help with navigation, I flew a hired helicopter from the airfield to the hills above my village. The navigation in the Welsh hills was fairly challenging but we found the area; after all, I knew the area well and so did my passenger. Soon we were above the relevant field at exactly 300 feet, at the agreed time, knowing that several people were stationed in each village in the valley below, cameras at the ready. Now all I had to do was orbit over the field.

This however proved to be surprisingly difficult. The wind in the hills was quite strong and gustier than I had expected. When I turned downwind we were just about blown off the hillside! I couldn’t slow down too much or I’d risk getting into vortex ring. The updraughts and downdraughts caused by the terrain meant that staying at exactly 300 feet was extremely difficult. To add to the problems, flying so low was probably illegal, since there were several farms around and closer than we had expected them to be. Would anyone see us and would they complain? It was yet another thing to think about. So I wobbled about the sky, trying to keep a very precise altitude in a twitchy little R22 as I did continuous tight turns over the field, which was actually far smaller than I had anticipated. It was not fun! I had originally agreed to stay up there for ten minutes to give the photographers below plenty of time. But after five minutes I had had enough. I was tired and this was difficult. I was incredibly relieved when my passenger finally told me the time was up and we could return to the airfield

Was it dangerous? I don’t think so. I was very careful and quite aware of the all the possible problems. But it easily could have been. Should I have done it? Probably not, since it was possibly illegal and fraught with potential problems. These days I am older and wiser. If I was asked to do such a thing again, I think I would refuse. It really isn’t worth the risk.

And the result as far as the wind farm was concerned? The helicopter could indeed be seen from several of the villages, but it was too small for anyone to get a convincing photo. However, the wind farm application was turned down on other grounds anyway and despite the difficulties I had had, I was delighted to have been able to play a fairly important part in the whole campaign. After all, how many other helicopter pilots can say they have simulated a wind farm?