Comair Flight 5191

Investigation

During the investigation, the Federal Aviation Administration (FAA) discovered that tower-staffing levels at Blue Grass Airport violated an internal policy as reflected in August 2005 verbal guidance requiring two controllers on duty in facilities that have combined radar approach control and tower with radar functions, with one controller monitoring air traffic on radar, and the other performing other tower functions including communications with taxiing aircraft. At the time of the accident, the single controller in the tower was performing both tower and radar duties. On August 30, 2006, the FAA announced that Blue Grass Airport, as well as additional airports that were understaffing their overnight shifts, would use two controllers on duty, or shift radar responsibilities to Indianapolis Center when only one was available. The FAA stated that a second controller would not have prevented the accident.

Comair discovered after the accident that all of its pilots had been using an airport map that did not accurately reflect changes made to the airport layout during ongoing construction work. The National Transportation Safety Board (NTSB) later determined that this did not contribute to the accident. Construction work was halted after the accident to preserve evidence needed for the investigation.

The NTSB released several reports on January 17, 2007, including transcripts of the CVR and an engineering report.

In April 2007, acting on a recommendation issued by the NTSB during its investigation of the Comair 5191 accident, the FAA issued a safety notice that reiterated advice to pilots to positively confirm their position before crossing the hold-short line onto the takeoff runway, and again when initiating takeoff. The NTSB offered four further recommendations: three measures to avoid fatigue affecting the performance of air traffic controllers and one to prevent controllers from carrying out non-essential administrative tasks while aircraft are taxiing under their control. The recommendations were partly prompted by four earlier accidents; the board was unable to determine whether fatigue contributed to the Comair accident. In May, acting on another NTSB recommendation, the FAA advised that pilot training should include specific guidance on runway-lighting requirements for take-off at night.

In July 2007, a Comair flying instructor testified that he would have failed both pilots for violating sterile flight deck rules. Later that month, the NTSB released its final report, citing the pilots' "non-pertinent conversation" as a contributing factor in the accident.

Probable cause

During a public meeting on July 26, 2007, the NTSB announced the probable cause of the accident:

The National Transportation Safety Board determines that the probable cause of this accident was the flight crew members' failure to use available cues and aids to identify the airplane's location on the airport surface during taxi and their failure to cross-check and verify that the airplane was on the correct runway before takeoff. Contributing to the accident were the flight crew's nonpertinent conversations during taxi, which resulted in a loss of positional awareness and the Federal Aviation Administration's failure to require that all runway crossings be authorized only by specific air traffic control clearances.

NTSB investigators concluded that the likely cause was that Clay and Polehinke ignored clues that indicated that they were on the wrong runway, failed to confirm their position on the runway and violated sterile flight deck rules.

Clay's widow strongly opposes the NTSB's assessment blaming the pilots, stating that other factors contributed, "including an understaffed control tower and an inaccurate runway map."