see more

UNITED STATES - AUGUST 10: A K-9 police officer walks through the US Airways terminal at the Philadelphia International Airport in Philadelphia, Pennsylvania, Thursday, August 11, 2006. Crude oil traded near its lowest level this month after a foiled terrorist attempt to attack airlines raised concern travelers will avoid flying, reducing jet-fuel demand. (Photo by Bradley C. Bower/Bloomberg via Getty Images)

UNITED STATES - AUGUST 10:  A K-9 police officer walks through the US Airways terminal at the Philadelphia International Airport in Philadelphia, Pennsylvania, Thursday, August 11, 2006. Crude oil traded near its lowest level this month after a foiled terrorist attempt to attack airlines raised concern travelers will avoid flying, reducing jet-fuel demand.  (Photo by Bradley C. Bower/Bloomberg via Getty Images)