The UK's £350 million ($570 million) Swanwick en route air-traffic-control (ATC)centre between Fareham and Southampton, Hampshire, is billed by National Air Traffic Services (NATS) as the largest and most advanced development of its kind in the world.

It is perhaps not surprising, therefore, that this ambitious project has encountered its fair share of teething troubles, albeit relatively late in its seven-year development programme. Up until the middle of 1995, development of the New En Route Centre (NERC)had been on schedule - the new building had been completed on time, the ATC simulation programme for controller training was ready to be implemented, and all the computer hardware and support equipment had been installed.

The problems, which have already delayed the planned opening date of the NERC by 15 months, to March 1998, stem from the unusually high number of "bugs" which prime-contractor Lockheed Martin is having to remove from the 1.82 million lines of software code at the heart of the system.

The software is designed to satisfy the 3,300 "functional requirements "for the 203 operational and engineering workstations at the Swanwick centre. The correct functioning of these consoles is critical if NATS is to meet its goal of providing an immediate 40% increase in en route airspace capacity over England and Wales, while "maintaining or enhancing" existing safety levels.


Million lines of software

Around 1 million lines of software were written specifically for the NERC, initially by IBM staff who had not previously worked on an ATC project. NATS believes that this contributed to the high level of errors, coupled with uncertainties for the workforce as IBM's Federal Systems division was acquired first by Loral, then by Lockheed Martin.

According to Dr John Barrett, London area programme director at NATS, the average number of defects per 1,000 lines of software code expected to occur in a project of this size is between eight and 12. "The overall average we have ended up with has been closer to 15 defects per 1,000 lines of code," says Barrett. "We are clearing them at a rate of 500 per month-there are still a lot of defects to remove," he adds. "We know where all the bugs are."

Based on these figures, the total debugging process for the 1 million lines of new code will have taken around 30 months to complete.

Meanwhile, during initial trials, the commercial off-the-shelf portion of the software seemed to be trouble free, and this was successfully integrated with the new software on a small network of workstations. When Lockheed Martin engineers attempted to get the system running on the full-scale network, however, it became clear that the software could not operate reliably.

"The system worked on 30 workstations, but when we tried to scale it up to 150 workstations we had difficulties," says Barrett. "It wouldn't scale up because of the very large number of latent defects."

The debugging must be finished by June if the planned operational date of March 1998 is to be met, to leave enough time for controllers to be trained for the new system. Barrett is confident that the June deadline can be met, however, with the system now "-98%there, in terms of functionality", he says.

Assuming that the software is running satisfactorily by June, the controller training programme will then become the "critical path", says Barrett. "The decision on the point at which operations start will be determined by the success of the training programme," he adds.

Any further delays in the already tight timetable will result in the opening date being pushed back until at least October 1998, however, to avoid risking interruptions to the northern-summer schedules during the switch-over.

"We are simulating every bit of the operational system that they [the controllers] will see," Barrett says. Experienced air-traffic controllers are being used to carry out "system usability trials", fine-tuning aspects such as the sizes and colours of symbols on the screen, and the functionality of the graphical user interface. It will also be possible for individual controllers to tailor the format of their display according to their own preferences.

Each console, or "sector suite", consists of three workstations with a 510 x 510mm Sony colour monitor, which displays primary data and the radar picture. Secondary information is shown on a smaller, adjacent screen.

Each airspace sector will be controlled by a two-person team, consisting of a tactical- and planner-controller, supported by an assistant. Co-ordination between sectors will be achieved through the electronic exchange of flight data. The planner will use electronic flight strips, although the tactical controller will initially use conventional paper strips.


Taining problem

"If [the system usability trials] throw up any major issues, then we are going to lose time," says Barrett. The problem is that the training programme cannot be fully implemented until the controller interface and functionality accurately reflects the way that the system will operate when the centre goes on line. While the software and user interfaces are being tested, minor changes are still being introduced.

"We have to have a system that has had an established period of integrity," says Gordon Doggett, centre manager for Swanwick. In the meantime, a training and development simulator, which consists of a small number of operational consoles, has been set up to allow initial training of instructors to begin.

The full training programme will be carried out in three phases, with the first ending in June, the second running between August and October, and the third between October and December. Each controller will take 17-21 days to complete operational conversion training. Swanwick will initially be manned by 360 civil and 27 military air-traffic controllers, backed by an operational support staff of 140.

George Dasher, managing director at Lockheed Martin Air Traffic Management, says that, despite the delays, the US company still has "a very healthy relationship" with NATS.

NATS signed a fixed-price contract worth £200 million with Lockheed Martin for the Swanwick project, resulting in the US company having to bear the brunt of the additional costs of the delay. Barrett confirms that, despite several amendments made to the contract with Lockheed Martin (such as a request for some additional workstations), the cost has "-grown very little. We are within budget for the systems we set in the first place", he says.


Wst Drayton fallback

NATS is, however, having to meet the estimated £9 million additional cost of keeping the London Area and Terminal Control Centre (LATCC) at West Drayton, near London Heathrow Airport, operational until Swanwick comes on line. As a stopgap measure, NATS has had to upgrade the LATCC to cope with the ever-increasing number of flights using the airspace above England and Wales. Doggett says that NATS could "-just about cope, if we had to, up to 2000"using the West Drayton site.

The LATCC may have to cope until close to that date if, as some sources close to the project suggest, a further slippage into late 1998 or early 1999 is likely. Lockheed Martin, for its part, will be hoping that NATS can avoid having to announce any further delays to the Swanwick project, with the US company leading a consortium which has already been named as the preferred bidder for the UK's planned New Scottish Centre at Prestwick, Scotland.

Source: Flight International