Britain’s NATS wants to pare lateral separation

 - March 26, 2008, 10:11 AM

Britain’s National Air Traffic Services (NATS) is stepping up operating trials aimed at making greater use of both en route and terminal area airspace. New procedures being evaluated include the use of parallel offset tracks in place of radar headings alone; closer spacing of parallel routes with autonomous operations; and the use of precision area navigation (PRnav) procedures for terminal area control.

At a January 23 meeting of the UK’s Business Aircraft Users Association (BAUA), Peter Legros, NATS’ head of airspace development, said that the use of parallel offset tracks for en route navigation will reduce the need for controllers to constantly change headings in five-degree increments. “In high winds, controllers might have to issue pilots with 10 heading changes in the space of just 150 miles,” he explained, adding that the use of parallel offsets would allow them simply to monitor flights rather than having to adjust them inefficiently.

Standing in the way of NATS’ desire to reduce the spacing between parallel routes to 10 nm is the UK Civil Aviation Authority’s insistence on 12-nm spacing (six-nautical-mile separation on either side of the route). Legros said that this requirement “does not seem logical” given that it is the same separation required in areas of Africa that have no radar coverage at all.

NATS is now trying to persuade the CAA to accept reduced containment values for navigational aids that would allow the 10-nm parallel separation. Eventually, the newly privatized air traffic controller provider would like to reduce the gap between parallel routes to seven nautical miles (3.5 nm either side). Legros said the reform would reduce controller workload and provide for dual route structures in capacity-constrained flight areas.

Meanwhile, British Airways is participating in a trial to evaluate the use of PRnav approach procedures (based on navaid accuracy of within one nautical mile) into London Heathrow Airport. NATS is now looking for corporate aircraft volunteers to participate in similar trials at the London-area Farnborough and Biggin Hill Airports next year.

BAUA chief executive Derek Leggett warned his members that they face “big increases” in charges for using controlled airspace if NATS does not succeed in achieving greater airspace efficiency. In the wake of post-September 11 airline traffic reductions, NATS is under pressure to boost revenues while also finding money for much-needed infrastructure improvements. The UK government, which last year controversially sold a 49-percent stake in NATS to a consortium of airlines, has ruled out providing state aid to keep the investment plans on track.