Manchester Airport is a civil airport with two large runways of 10,000ft (3km). The airport has customs clearance and four Fixed Based Operators. Two of the FBOs operate 24 hours a day. An airport slot is required for landing or departure. The airport is the third busiest airport in the UK in terms of passengers and the busiest outside of London. It is the only airport in the UK other than London Heathrow Airport that operates with two runways over 3km. It is located 14km southwest of Manchester city-centre.