On December 6, 1999, at approximately , a runway incursion occurred involving United Airlines flight 1448 (a Boeing 757) and FedEx Express flight 1662 (a Boeing 727) on Runway 5R/23L. Shortly after landing on Runway 5R, United 1448 was instructed by the air traffic control tower to taxi to the gate, part of the instructions including crossing Runway 16. Due to the low-visibility conditions that night, the pilots became disoriented and turned down the wrong taxiway, which led them back towards the active runway they had just arrived on. The tower controller, unaware of United's mistake, cleared FedEx 1662 for takeoff on Runway 5R. United 1448 then confirmed with the controller that they should cross the runway in front of them (neither party aware that they were in fact not near Runway 16) and the aircraft continued moving towards Runway 5R/23L.