|Diagram of the XMAN system. Photo: NATS
[Avionics Today 12-11-2015] A project to cut aircraft holding times at Heathrow Airport has been so successful that the trial procedure has now entered permanent operational service. Known as Cross-border Arrivals Management (XMAN), the procedure sees NATS Air Traffic Controllers (ATCs) in the United Kingdom working with those in the surrounding airspace in France, Ireland, Belgium and the Netherlands to slow aircraft down up to 350 miles away from London in order to minimize holding times on arrival.
Since April 2014, NATS has recorded a reduction of up to a minute in holding times for those aircraft influenced by the trial. This equates to annual savings of 8,000 tons of CO2 and $2.5 million in fuel, as well as a reduction in noise for communities beneath the holding stacks.
Heathrow is scheduled to 98 percent capacity and relies on the continuous flow of traffic that the stacks provide. Traditionally, NATS could only influence an aircraft’s approach once it entered U.K. airspace, which can be only 80 miles from the airport. This previously limited the chance to manage the inbound flow of traffic.