Control of most of the UK's skies will transfer to a new centre on 27 January. Can it be done without disruption?

At 02.29 on Sunday 27 January, a pilot entering UK airspace and calling "London" will be speaking to the London Area and Terminal Control Centre (LATCC) in West Drayton, near London Heathrow, which started operations in November 1966. A minute later, on the same frequency, the pilot will be speaking to a controller at the new London Area Control Centre (LACC), 110km (70 miles) south-west at Swanwick.

The pilot will barely notice the join - but he or she will be taking part in a piece of aviation history 12 years in the making. When the West Drayton centre began service, most civil air traffic was controlled procedurally, without radar. Radar arrived in 1971, transferred from the centre at Heathrow airport. Flight-plan computer storage was introduced in 1975.

Now West Drayton's old computer and software system, despite frequent upgrades, is nearing capacity. Swanwick LACC, on the other hand, has a system, which, when it begins operations at the end of this week, will use less than half the computer storage and processing power it has available.

Although the old round, horizontal controller displays in the Area Control workstations at West Drayton today have relatively advanced amber traffic symbols and data on their dark surfaces that would have amazed 1970s controllers, they are essentially the same cathode-ray tube displays in place 30 years ago. At Swanwick, the cool, blue-grey, vertically set displays present clearer traffic information, configurable to highlight traffic data and system information that a given sector-controller needs to see. An array of alternative traffic configurations or information windows is just a mouse click away.

New tools

Controllers' tasks will not change in the transition from one centre to the other - only the tools. Although the new workstations at Swanwick can operate with electronic flight progress strips (FPS) instead of the paper ones controllers are used to, the new LACC will start its life with controllers sticking to what they know - except that the Swanwick FPSs will be mini-strips with the same format. They are smaller so as not to take up the amount of workstation surface space as the full size ones at Drayton.

When the controllers become adept at exploiting the advantages the new tools Swanwick offers, the much-loved paper FPS will no longer be used. The advantage of the "electronic FPS" is that any controller can call up the latest clearance status on any aircraft, and the flight's details can be datalinked to neighbouring foreign area-control centres that are acquiring responsibility for the aircraft.

Transfer of control from LATCC to the LACC will be a phased process beginning at 14.00 GMT on "O Day" - 26 January (see transfer timetable panel). It will require full shifts of controllers to be on duty at both centres at the same time. But this is not a problem, says National Air Traffic Services chief operating officer Colin Chisholm. For weeks there have been enough controllers to keep LATCC operating normally while full shifts of controllers have been training in handling the equipment at the new centre. At this time of the year, with traffic at a seasonal low, shifts do not have to be as large as they are in the high season, Chisholm adds.

From 14.00 to midnight on O Day, transfer of essential back-up services to active control take place: the flight information service and flow management are taken over by Swanwick. At midnight, LATCC will suspend datalink co-ordination with adjacent air traffic centres, and send traffic estimates manually - not difficult because traffic levels at that hour are low. At 00.30, the Swanwick controllers will begin "shadowing" the LATCC operation, and ATC assistants at both centres will produce FPSs manually, because the computer will, temporarily, not be printing them out.

At 02.00, each Swanwick sector-team will contact the corresponding LATCC team on the transition telephone lines, establishing the current active flights in the sectors and begin actively to monitor the flights. By 02.30, the required telephone configuration changes should have been made and the handover of traffic responsibility to Swanwick can start, each flight handed directly by the LATCC controllers to their Swanwick counterparts. Aircraft by aircraft, Swanwick will take control, and the transfer will be complete.

According to LACC general manager Gordon Doggett, if any of the automation fails, Swanwick has practised operation in manual mode, and can revert to it while the duty engineering team sorts the problem out. Again, with traffic levels so low, it will not create a difficulty at night, says Doggett. When the morning "rush" starts, however, if Swanwick is still in manual, traffic-capping will be applied, meaning delays and diversions to keep the flow manageable.

The resulting delays to take-offs, or diversions to incoming aircraft, would be about the same as could be expected if there were "a poor weather day in the London TMA [terminal area]", says Doggett. In a real emergency, reversion to West Drayton would be an available option for about 36h, says Chisholm, but after that, the new LACC is on its own.

Teething troubles

Doggett expects some teething troubles in the first six months of operation, adding that anyone responsible for putting a very complex new system into operation knows that the unforeseen will occur. He says, however, that LACC is primed to expect the unexpected. For example, as a precaution, traffic levels are planned to be capped at 30% below peak high season levels for the first 10 days of Swanwick operation, relaxing to 25% 10 days later, and 15% below peak levels after 30 days. At this low-traffic time of year, the only effect of the planned capping will be slight delays during peak hours, adds Chisholm.

Meanwhile, West Drayton, now reduced to the London terminal control centre, will continue in operation until the last of its civil and military components (see "Who controls what" panel) are transferred to Swanwick in 2007.

Source: Flight International