Terminal 5, the new first terminal at Heathrow, since Terminal 4 opened in 1986, opened for passenger use on 27 March 2008. The first two weeks of the terminal's operation were disastrously disrupted by a number of problems with the terminal's IT and baggage systems which caused over 500 flights to be cancelled. It has since recovered and is a key part of Heathrow upping its game to remain the premiere hub in Europe. Terminal 5 is exclusively used by British Airways as their global hub. Other One World carriers including American, and BA sister-carrier Iberia remain at Terminal 3 though Iberia will probably move over to T5 as it is expanded. Some BA flights still remain at Terminal 3. Under construction for 5 ½ years, T5 is the largest freestanding building in the UK. It consists of a main terminal building, Concourse A, and two satellite buildings linked to the main terminal by an underground people mover transit system. The first satellite, Concourse B, includes dedicated aircraft stands for the Airbus A380, which BA is expected to begin flying in 2013. Concourse C opened in May 2011. The Terminal 5 complex is located on the western part of the airport away from the London Heathrow Central complex which itself is being heavily redeveloped.