When they had the RSPB bird watch weekend in January you had to record how many different types of bird that visited your garden within an hour. I counted two collared doves, a wood pigeon, a couple of jackdaws a blackbird and a robin – a total of seven. In that same hour I also saw three airliners, one microlight, one helicopter, four light aircraft, an RAF Hercules  and a VC10  – eleven in all. Chipping Norton is a busy place for both avian and aviator alike. Even those who have no interest in aviation can’t fail to notice that there is a lot going on up there. This article is aimed at those who want to know a little more and who might want to be reassured that they are as safe as is possible. As befits a technical business aviation is full of acronyms and I will try and introduce a few of these as gently as I can.

In fact there is a good reason you see so many aircraft here. Chipping Norton is in what the Civil Aviation Authority call an AIAA (An Area of Intense Aerial Activity). This is not surprising as within a few miles we have RAF Brize Norton, RAF Benson, Little Rissington, Abingdon, Oxford Kidlington, Enstone, Wellesbourne, Hinton in the Hedges, Weston on the Green, and Turweston Airfields. There is also gliding at Edgehill and Bicester. What’s more we are almost underneath a major airway. Have a look at the local extract from the 1:500000 scale chart and you will see that Chippy is not only the highest town in Oxfordshire but is right up there with the aircraft too. For those people who move to an area and then complain about the number of aircraft I would like to point out that, in the case of all those under the age of sixty, the airfield was almost certainly there first.

First of all aviation is split into three groups – Military (who have their own rules), Commercial (Airliners) and General Aviation (the rest including everything from small business jets to hot air balloons including light aircraft, historic ex military aircraft, microlights and gliders). In Chipping Norton we get all three, though the commercial stuff is very high in the sky so you needn’t worry about it, unless something falls off or they empty the sewage compartment by mistake!

All of these aircraft fly in two kinds of airspace, controlled (of which there are various kinds) and uncontrolled. Aircraft operating in controlled airspace, which includes the air corridors and routes that commercial traffic travels in, the airspace immediately around an airport, certain manoeuvring areas and the like, rely on some form of air traffic control to keep them apart. The aircraft are told what to do, and although they are responsible for keeping a look out and not bumping into someone who isn’t where they should be, and this keeps everything very safe. In the case of commercial airliners they are controlled one way or another from the start of their journey to the finish and fly by special rules, more of which later. Indeed the only time when they are not directly being controlled in terms of height, course and speed by Air Traffic Control (ATC) is the couple of minutes during and after take-off and before landing. Air traffic controllers will point out to you that most accidents happen on landing or take off – the only part of the flight where the pilot is fully in charge, but they might be biased! There are very, very few mid air collisions involving commercial aircraft, so the odds on one falling on Chippy are very,very slim.

The second kind of airspace is, unsurprisingly, called uncontrolled airspace. As its name implies it is not controlled by any kind of air traffic service, though there may be services, such as the Lower Airspace Radar Service, locally provided by Brize Norton, to help pilots with traffic information and avoidance information. The airspace immediately around Chipping Norton is uncontrolled airspace. Here the basic rule to avoid collisions is, "see and be seen". It is up to the pilot to keep a good look out – and if you see anything coming at you head on, turn right – very quickly! The basic rule is keep right (bit like driving in France, but less stressful and much safer). When following a ground feature, such as a road or a railway, to avoid someone coming the other way you keep the feature on your left. There are also rules about powered aircraft giving way to gliders. Gliders giving way to balloons, and balloons doing what they like. Bit like the steam giving way to sail. These rules are based on the ability to get out of the way – a hot air balloon doesn’t have much independence in which way it is going and it has no ability to accelerate or slow down. However, a wise pilot will not put his or her hot air balloon in the path of a C17 Globemaster transport aircraft on its way into RAF Brize Norton and rely on the law to get them out of trouble later. The board of enquiry would unlikely to be attended by the survivors from the balloon!

To complicate matters further there are two sets of rules by which aircraft fly – one is called VFR, the other is called IFR, they stand for Visual and Instrument Flight Rules. The former is what the majority of light aircraft and microlights follow – it is based on being able to see where you are going and keeping a good look out. The latter doesn’t make any such rash assumptions as to visibility and is how airliners are flown – it requires an external controlling agency, in the form of an air traffic controller when inside controlled airspace. IFR is needed because people don’t want to wait for their holidays until the weather is suitable for VFR all the way there and back!

A question that I have often been asked is how low can you legally fly? In general this is defined by Rule 5 of the Rules of the Air Regulations 1996. In rough terms this says that apart from landing and taking off you must be at least 500 feet from any person, vessel, vehicle or structure (though the CAA are currently reviewing this). There is also a requirement to be able to glide clear from a built up area, such as Chipping Norton. In addition there are further rules covering built up areas, conurbations and outdoor events with gatherings of over 1000. In the case of built up areas aircraft have to be at least 1,500 feet above the highest point in the area and able to alight clear if an engine fails. In addition single engined aircraft are designed so that they can glide to, and land in an average farm field without serious risk to the occupants or public in the case of such a failure. For large out door events aircraft have to be at least 3000 feet away, either vertically or horizontally. These rules also help reduce the noise nuisance from light aircraft, something reinforced by noise-abatement policies adopted by airfields such as Enstone designed to make them good neighbours. As I said before, the laws make simple explanations difficult. Another problem with this is that the average person is wholly incapable of estimating how high an aircraft is above them. In terms of being illegally too low, if you can’t read the registration letters under the wing then it probably isn’t – but don’t quote me as an authority for that. In practice in this country most light aircraft travel round between 2000 feet and 5000 feet above mean sea level. Chipping Norton is about 800 feet above mean sea level so they should represent no direct danger to those on the ground. The military are exempt from the low flying rule, though there are restrictions on what they can do and where, but they do their best to avoid being a nuisance and try to avoid over flying sensitive areas.

The police also have special dispensations – which explains why you see the Thames Valley Police helicopter hovering over the police station on a regular basis below 500 feet. The fast jets spend much of their time between 200 and 500 feet – which is why you can view them from above from some building in Chipping Norton as they pass by. These different operating heights help explain why they don’t bump into each other despite operating in uncontrolled airspace.

All pilots, professional or amateur, receive extensive training in all these rules of the air, the types of airspace, air traffic control services available to them. What is more they have to pass exams in them before they may fly on their own. In addition they are taught where to get weather, airfield information and how to access special "Notices to Airmen" called NOTAMs that give important safety information (for example where the Red Arrows will be flying). Chipping Norton may be in a very busy block of airspace, but the chances of anyone bumping into each other are fortunately very small. There is no need to invest in tin hats.

© David Nickson 2003