Multi-role tanker aircraft provide two vital operational services for the Armed Forces. Air-to-air refuelling enables other aircraft to stay airborne for longer. Tanker aircraft also transport military and other personnel. In March 2008 the MOD signed a contract for a new air-to-air refuelling and passenger air transport service. The service will be based around 14 Future Strategic Tanker Aircraft (FSTA), FSTA is being procured through a 27-year, £10.5 billion, private finance initiative (PFI) contract,