The BHPA operations manual referred to below was the one current at the time of writing. Unfortunately I have no accurate record of the date it was written. I note that in their BHPA pilot handbook 2000 edition the BHPA quietly 'cops out' of the problem of giving way to the pilot with the hillside on his or her right by referring to it as a 'UK ridge-soaring convention'!

An excellent publication available at most gliding clubs is the BGA 'Rules and Laws For Glider Pilots'. This costs about a pound and contains almost eveything you need to know about airlaw for paragliding and hang-gliding. It is also updated regularly.

There seems to be much confusion about airlaw regarding collision avoidance. Odd, considering that there are actually so few rules. So what is the problem? Quite simply overcrowding. We are trying to make practices developed for infrequent use serve the purpose of tight traffic control.

So what is to be done? Do we just give up and have a free for all? Let's try and have a cool look at things first!

Where does airlaw come from? The basic rules for collision avoidance are actually older than manned flight, originating as shipping rules put laid down by the Admiralty in about 1860. Let us begin with the three basic rules;

'When two aircraft are converging at approximately the same altitude the aircraft which has the other on its right shall give way.'

In open sky this is quite straightforward and logic dictates that the necessary manoeuvre is for the aircraft giving way to turn right in order to pass behind the other aircraft. This ties up nicely with the next law;

'When two aircraft are approaching each other head on, or approximately so, each shall alter course to its right.'

And the following one too;

'Overtaking aircraft shall at all times keep out of the way of the aircraft being ovetaken by altering course to the right, - '

So far so good. We only ever need to turn right to keep out of other peoples way. Nice and simple - or is it?

Sadly no. The full text of the last law continues;

' - provided that a glider is overtaking another glider in the UK may alter its course to the left or the right.'

Why should this be? Basically the (UK) law recognises that glider pilots are not simply flying from A to B in straight lines because they are often constrained by geological and meteorological features. The immediate implication of this is that glider pilots are going to have to be much smarter than power pilots in order to sort things out. We knew that already of course!

These laws seem to cover everything. So what's the catch? The catch is the next catch-all law;

'Whereas aeroplanes shall when converging give way to aerotows and gliders, and gliders shall give way to balloons, it is nevertheless the responsibility of all pilots at all times to take all possible measures to avoid collision.'

This law has two principles. One is that aircraft most able to take avoiding action should do so (steam gives way to sail and oar!). The faster aircraft normally turns to avoid the other. The second principle, if taken literally, implies that we should all stay on the ground. Nice one, problem solved! Thankfully, careful examination of the logic of the second reveals that when we are on the ground we are not pilots. Phew. But what the hell does it mean? In essence we can expect pilots of faster and more manoeuvreable aircraft to avoid us but we should try and keep out of their way. Common sense.

The other interesting thing about this catch-all is that it could be interpreted as having another specific implication. It could be interpreted as meaning that if an organisation, such as the BHPA, has additional rules on collision avoidance then we should be required by law to follow them. In general this is true, but, what we legally do have is the right not to follow such rules if we feel that they are detracting from the safety of all concerned, however we may be required to justify, in court, why we did not follow them. If we reach that stage we are almost certain to be wrong!

What are these other rules? Oddly enough I was unable to find any reference in the BHPA operations manual. I asked some friends to search and they could not find them either, so finally I emailed a senior BHPA officer, and got no reply. So what does all this mean. It would appear that the BHPA has not formally adopted the the BGA 'ridge rules' which we are all so carefully taught.

In fact the BGA 'ridge rules' are not rules at all. They are a set of 'recommended practices' and certainly not law. Let us have a look at them.

'Make all turns outwards, away from the ridge.'

This seems sensible enough until you want to take a thermal which is on the ridge side rather than the valley side. Is there a reason why this recommendation is so specific? Remember that these recommendations were developed for sailplanes in many of which it is difficult to see behind much at all. So, if you are flying crabwise across wind and intend to turn towards the ridge there is no way you can see the space you are going to occupy. However, if you are on a paraglider and can see right behind you is there any reason why you should not turn towards the ridge if it is visibly and aerologically safe so to do? No. There is no reason. Safe is safe, as long as you are right and there is no one behind you.

'The glider with the ridge on its right has right of way.'

Given that we normally give way by turning right it is impossible so to do if that means flying into the hill and this practice seems fair enough and common sense. However this 'rule' has been exploited by some as a means of pushing others off the ridge or out of the lift by demanding right of way. Any pilot thinking this is OK should be reminded of the earlier 'catch-all'. If you are flying in such a manner you are clearly not 'taking all possible measures to avoid collision' and are breaking the law.

'A glider overtaking another glider must pass between that glider and the hill.'

This recommendation causes some problems among hang-glider and paraglider pilots. Again remember it comes from sailplane practice where pilots are seldom flying just a few feet from the hill as we do with HGs and PGs. Clearly you cannot pass another glider on the hill side if there is insufficient room.