The NTSB also noted that during the previous performance review, a supervisor had noted four deficiencies in the local controller who ultimately worked the accident aircraft. These deficiencies were not addressed prior to the accident, and two of the deficiencies were apparent in the accident sequence—her loss of situational awareness and aircraft misidentification. The NTSB's investigation of the crash revealed a failing system in the air- and ground-traffic control facilities at LAX: the ground radar system worked intermittently, and was not functioning at the time of the incident; the blind spot, from the control tower, when looking at the spot where SkyWest 5569 was waiting on the runway; the system for ground controllers in the tower to pass flight progress strips to the local controller did not support the local controller's workload; aircraft on runways were not required to turn on all their external lights until rolling for takeoff. All these issues were rectified at LAX following this incident. At the time of the accident, ATCs at LAX used all four runways (North Complex runways 24L and 24R, South Complex runways 25L and 25R) for mixed takeoffs and landings. One of the NTSB recommendations was that the runways be segregated with only landings or departures taking place on an individual runway. This recommendation was implemented, but not until after another incident, when on August 19, 2004, a Boeing 747 landing on 24L passed only above a 737 holding on the same runway. Aftermath LAX now prioritizes the use of the outboard runways (24R and 25L) for landings and the inboard runways (24L and 25R) for takeoffs, though mixed operations may occur in certain situations. Additionally, a new control tower was built at LAX, in a more central location, significantly taller and with a better vantage point, allowing visibility of all runways and critical taxiways at the airport. Before this accident, the FAA issued a ruling that required airlines to upgrade the flammability standards of materials on board, but the USAir plane had been built before the effective date of those requirements and had not yet been modernized. It was scheduled to be upgraded within the next year. By 2009, all aircraft operating in the United States were compliant. Dramatization The story of the disaster was featured in a 9th-season episode of the Discovery Channel Canada / National Geographic series Mayday. The episode, titled "Cleared for Disaster", explores the events surrounding