DENVER — An airplane flying from Washington D.C. to Las Vegas has been diverted to Denver International Airport after a passenger tried to open an exterior door on the plane while it was in flight. DIA spokesman Jeff Green says that United Flight 223 was diverted to Denver at 5:10 p.m. Saturday, and police who met the plane at the gate took the passenger into custody. Green told the Denver Post that it is "virtually impossible" to open an exterior door in mid-flight.