Driving over to the air traffic control centre, topped by the tower, it's difficult not to think in terms of Bond movies. Inside, the banks of round screens, with the green diamonds moving in jerky lines, only add to the illusion. There are also square screens, banks of lighted buttons, phones and headsets - all the paraphernalia of a highly technical environment.

Of course, the green diamonds represent real aircraft high in the sky above Ireland. The numbers beside them indicate their height and speed. The host of planes high in the sky at any one time makes for crowded screens.

The controllers, sitting in Shannon airport, must ensure that the planes fly safely and efficiently. Air traffic controller Sharon Cunningham says the trick is to visualise what's happening on the two-dimensional screen in 3D.

In the zones close to the airports the minimum separation between the planes is five miles laterally and 1,000 feet vertically. Further out, in the buffer zone, the lateral separation increases to 10 miles while outside the domestic zone planes must be at least 10 minutes apart, for there, they are now out of radar, operating in a procedural environment.

The environment is far more relaxed than the movies would lead you to believe. However, the job does demand rapid responses. "If you're in a situation the decisions have to be made immediately. There's no question of going for a cup of coffee and thinking it over," says Cunningham.

She has never been in a "near-miss" situation and says the safety record is very good. Shrugging off the stress, she says: "Every job has its moments. Initially, I was apprehensive, it seems very daunting, but, with experience, you cope."

Cunningham went to school in St Anne's in Tipperary town, doing her Leaving Cert in 1986. She joined the civil service for a year, then spent six months in London working for a health board, before returning to the civil service in Dublin. An internal ad, seeking trainee air traffic controllers (The Irish Aviation Authority is now a semistate), attracted her attention.

"I suppose it was something unusual - different and challenging. I started off as an ATC assistant. Initially I was writing up flight plans, doing administrative and clerk type work. A lot of this work has since been automated." She trained in the classroom and on the job (see career focus for current training).

The job is reasonably mathematical, she says, with separations between planes done in degrees, distance and time. It becomes more mathematical if the radar fails and calculations must be made manually. But, spatial visualisation skills are probably more important than mathematical skills, she says.

Cunningham works on high-level and low-level radar (she was the first woman to qualify as a high-level controller, in Ireland). She also controls ground movements, on the tower - anything moving except traffic on the runways, she explains. It could be routine patrols or bird-scaring patrols. In effect, this is traffic control rather than air-traffic control. Most ATCs work in pairs, with a planning controller and an operating controller on each team. "If there are no conflicts, the planning controller gives out levels. If there are conflicts, then it becomes the radar controller's job."

Each day begins with a comprehensive briefing from the controllers who are going off shift. "They must fill us in the current picture - any problems with navigational aids, any active military zones (so we can reroute civilian traffic), if there are landing delays . . ."

The work must go on a 24-hour basis so the ATCs work on a shift basis. "You get good time off but, on the downside, you have to think very far in advance when it comes to social events. I rotate between here and the training centre, where I work as an instructor, so, for a couple of months of the year, I am back on a five-day week, working nine-to-five."

As to the future, Cunningham enjoys her job and plans to stick with it.