Belfast International Airport: Preparing for emergencies
"Easy, six-two, mike, uniform, runway two-five, cleared to land, wind one zero zero degrees, four knots."
An air traffic controller at Belfast International Airport, Aldergrove, is giving final instructions to an Easyjet flight landing on the main runway, known as Runway 25.
Any pilot who flies to or from north America or Canada from northern Europe knows exactly where to find this particular airport, even if he has never landed there.
For aircraft needing an emergency landing, Aldergrove, County Antrim, is the main one on the island of Ireland and the most westerly in the UK.
It holds a special status from the Civil Aviation Authority, called "Cat III B".
A team of staff run by the airport's engineering supervisor, Norman Lindsay, keeps its specialised lights in readiness day and night, all year round.
"The lights are of a very high technical standard," said Norman.
"It's a coded runway. It allows us to give far better visibility to pilots than they would maybe get at other airports that don't have that Cat III capability."
There are more than 2,000 bulbs and LEDs on the runway, with 181 down the centre line alone.
The runway is well over 9,000 ft, or more than 2,700 m long.
If more than nine lights were to fail at any one time, it would not meet the Cat III standard, so the team makes regular checks, driving along the runway between flights to ensure that this never happens.
But twice a year, Norman must make visual checks at dusk from the air, covering all the likely approaches. This time, I have been invited to come along.
We spend a fascinating hour flying around the airport in a small Chieftain twin-engine aircraft as its captain, Ken Watt, and Norman sort out the CAA paperwork.
At regular intervals they ask the control tower to switch different sets of runway lights on and change their intensity, faithfully noting the results.
They are very clear from several miles away as the last light of the spring evening fades.
Even so, one or two lights do not look as clear as Norman would like, and are scheduled for investigation by his team the following morning.
Shortly afterwards, we land.
Runway two five is examined every day. It is also checked from the air twice a year - ready for every flight and any potential emergency.