OBSESSIONS / Plane crazy: They are almost exclusively white, male and British. David McKeown charts the exotic world of the plane-spotter

When Heathrow's Terminal Two was built, a large public viewing gallery was included on the roof. I imagine the architect's drawings portrayed healthy Home Counties families performing the royal wave to airliners bearing departing relatives. What I saw on a Saturday afternoon in 1994 was very different. The roof of Terminal Two has become a second home to legions of plane-spotters.

In the public consciousness, train-spotters have a much higher profile. We've all seen them huddled against the elements (and the abuse) on the end of platform 12 at Crewe. It is all too easy to dismiss plane-spotters in the same breath. In fact, they are a much more exotic breed.

Plane-spotters are more profitably compared to bird-watchers. Sensible clothing, thermos flasks and binoculars are much in evidence. There is a buzz of activity as each new arrival alights. The markings on its tail, wings and body are examined with expert eyes, details are recorded and photographs taken. Special excitement is reserved for rare migrants paying unscheduled visits to our shores.

So what are all these grown men doing on the roof at Heathrow? The point of plane-spotting is to identify each aircraft by its registration number and to record each new sighting in a book. One publication covers all the aircraft in Britain; another lists every airliner in the world. There are military books, too, for those who enjoy long weekends in Lincolnshire ditches. It is not known whether any of the Greenham women were plane- spotters in drag.

Plane-spotters are almost exclusively white, male and British. There is no such thing as a black female plane-spotter from Uganda. They have better things to do. I did once meet a spotter at Seattle airport, but he turned out to be a British Airways steward on his day off. 'The rest of the crew has gone skiing, but I'm a bit behind on my Air Alaska list,' was his excuse.

The sheltered area on the highest point of the roof is as busy as the Tokyo stock exchange. Elsewhere, there are solitary figures, generally older and more furtive. Here, I find Mick from Tottenham. Mick started spotting when he was made redundant five years ago. 'I'm here two or three days a week. As hobbies go, it's cheaper than most. I still get a kick out of watching a Jumbo land. It's incredible to think that the last time it touched the ground it was in New York or India.'

Phil has a less poetic attitude. 'I took the family to Majorca last year. I spent the whole week at Palma airport. It was great for the German charters.' His wife is either very indulgent or can't stand the sight of him. Graham, down for the day from Ipswich, is envious. He spots 'whenever she lets me, about once a month'. Mike used to be more interested in military aircraft, visiting all the big air shows in Germany. He regards the end of the Cold War with ambivalence. 'It's rare to see a military aircraft in the air nowadays.'

Meanwhile, the 'spot' of the day has just taxied out. All eyes turn to the all-white Air France Boeing 747 that has been lying low around the back of the cargo terminal. Further conversation is futile. I leave as the Jumbo thunders down the runway.

So what about next Saturday? Well, a friend swears that he saw someone with a camera, notebook and relevant publication at Exeter bus station last week. Collecting bus registrations might be less expensive than collecting Ming vases, but I think I'll just go to a football match instead.

Heathrow Viewing Area is open throughout the year from 9am until half an hour before dusk.

Publications and equipment available from The Aviation Hobby Shop, Horton Rd, West Drayton (0895 442123)

(Photograph omitted)