"NATS, the UK’s leading provider of air traffic control services, handles 2.2 million flights and 220 million passengers in UK airspace each year. Originally collaborating in the 2013 EUROCONTROL SWIM Master Class, Cirium and NATS developed a prototype to demonstrate how reduced stack holding over London Heathrow could provide both economic and environmental savings. The successful project, now fully operational, uses Cirium Sky to manage, store and publish arrival sequence and temporal information to the adjacent control centres. In its first few years, it has saved more than 8,000 tonnes of CO2 and £1.65 million in airline and ground costs."