During the September 11, 2001 attacks, two of the four airplanes hijacked and crashed by al-Qaeda members were United Airlines aircraft (United Airlines Flight 175 was flown into the south World Trade Center tower; United Airlines Flight 93 was crashed in a field in Pennsylvania after the passengers fought back against the hijackers). An airline industry downturn resulted, and coupled with economic difficulties, skyrocketing oil prices, and higher labor costs, the company lost US$2.14 billion in 2001. In the same year United applied for a US$1.5 billion loan guarantee from the federal Air Transportation Stabilization Board established in the wake of the September 11 attacks.[36] After attempts to secure additional capital failed, UAL Corporation filed for Chapter 11 bankruptcy protection in December 2002 and