Comair Flight 5191

Date

27 August 2006

Phase of flight

Takeoff

Location

Blue Grass Airport, Lexington, Kentucky, United States

Aircraft

Bombardier CL-600-2B19 (CRJ-100)

Registration

N431CA

Operator

Comair, a Delta Connection carrier

Flight

Comair 5191

Occupants

50

Fatalities

49the captain, the flight attendant and 47 passengers; the first officer survived with serious injuries

Investigating body

National Transportation Safety Board (United States)

Final report

NTSB/AAR-07/05

Report date

26 July 2007

Report title

Attempted Takeoff From Wrong Runway, Comair Flight 5191, Bombardier CL-600-2B19, N431CA, Lexington, Kentucky, August 27, 2006

On 27 August 2006, about 06:06 eastern daylight time (local time), Comair Flight 5191, a Bombardier CL-600-2B19 (CRJ-100) registered N431CA, crashed during take-off from Blue Grass Airport, Lexington, Kentucky. The crew had been cleared to take off from runway 22, which was 7,003 ft long, but lined up in the dark on runway 26, a general aviation runway 3,501 ft long, and began the take-off roll. The aircraft ran off the end, struck an earth berm, the airport perimeter fence and trees, and burned. The captain, the flight attendant and 47 passengers were killed; the first officer survived with serious injuries.

The National Transportation Safety Board (NTSB) found that adequate cues were available on the airport surface and in the cockpit to guide the crew to runway 22, and that the crew did not use them or verify their runway before take-off. It also found that a Federal Aviation Administration (FAA) rule let a clearance to taxi to one runway authorise crossing others without a specific clearance.

A wrong-runway take-off is a runway incursion, and this one shows how a simple taxi, flown with a relaxed cockpit discipline, can end in catastrophe. Its lessons on verifying the runway, the sterile cockpit and confirmation bias apply to every crew.

The flight

Flight 5191 was a scheduled passenger flight under 14 CFR Part 121 from Lexington to Atlanta, Georgia, operated by Comair, a Delta Connection carrier. The taxi and take-off took place about an hour before sunrise, in night visual meteorological conditions, with the moon below the horizon.

The captain, aged 35, had 4,710 hours, including 3,082 hours on the CL-65 type and 1,567 hours as pilot-in-command on it. The first officer, aged 44, had 6,564 hours, including 3,564 hours on the type, and was the pilot flying. Both had had rest periods longer than required, and the NTSB found insufficient evidence to determine whether fatigue affected their performance. The aircraft, built in 2001, was properly maintained and showed no evidence of any structural, engine or system failure, and weather was not a factor.

The crew checked in at 05:15. On the ramp they first boarded the wrong aircraft and started its auxiliary power unit before a ramp agent redirected them.

The airport

Blue Grass Airport had two intersecting runways. Runway 4/22, the air carrier runway, was 7,003 ft long and 150 ft wide, with high intensity edge lights; its centreline lights and runway end identifier lights were out of service because of construction. Runway 8/26, used for about 2% of operations, was 3,501 ft long and 150 ft wide, but its paint markings limited the usable width to 75 ft. It was restricted to daylight VFR operations by aircraft under 12,500 lb, and its edge lights had been disconnected in 2001.

A construction project was nearly complete. Since 20 August the old section of taxiway A leading to runway 22 north of runway 8/26 had been closed and barricaded, and a former connector had been renamed taxiway A. The crew's airport chart still showed the old labels, and the local notice to airmen about the closure was not in the ATIS broadcasts on the day or in the flight paperwork. From the air carrier ramp, taxiway A crossed runway 26 on the way to runway 22, and the runway 26 hold short line was about 560 ft before the runway 22 hold short line.

The accident

During the before starting engines checklist, the first officer's take-off briefing referred once to runway "two four"; the captain corrected him, and the briefing then referred to runway 22 three more times. The first officer remarked that when he had landed on runway 22 in the early hours of the previous day, lights had been out "all over the place". Both pilots' heading bugs were set to 227°, the magnetic heading of runway 22. The captain abbreviated his taxi briefing to "Comair standard".

At 06:02 the controller cleared the flight to taxi to runway 22, which under the rules then in force authorised it to cross runway 26 without stopping. Between 06:03:16 and 06:03:56 the pilots held a conversation unrelated to the flight. At 06:04:33 the captain stopped the aircraft at the hold short line for runway 26, while the first officer completed the before take-off checklist and welcomed the passengers.

At 06:05:15 the first officer reported ready. The controller cleared the flight for take-off; neither of them mentioned a runway number. The captain taxied across the hold short line, turned onto runway 26 at 06:05:41 and handed control to the first officer, and take-off thrust was set.

As the aircraft passed the intersection with runway 22, the first officer remarked on the lack of lights and the captain agreed. At about 06:06:24 the aircraft passed the last speed, about 103 kt, from which maximum braking could have stopped it on the runway. At 06:06:31 the captain called "V one, rotate" at 131 kt, 6 kt early for V1 and 11 kt early for VR, then exclaimed "whoa". The first officer pulled the control column fully aft and the aircraft rotated at about 10° per second, three times the normal rate. It struck the berm, became airborne briefly but climbed less than 20 ft, reached 137 kt, and hit trees about 900 ft beyond the runway end. The main wreckage came to rest about 1,800 ft beyond the end of runway 26 and was destroyed by impact forces and a post-crash fire.

Bombardier calculated that the CRJ-100 needed 3,593 ft to reach a V1 of 135 kt and 3,744 ft to begin rotation: more than the whole of runway 26.

The investigation

The cues were there

The NTSB found no signs or markings at Lexington that failed to comply with FAA standards. Observations from a CRJ-100 at night showed taxiway location signs visible along the whole route, and the runway 26 holding position sign and runway 26 numbers visible; the signs at the critical points of the route were lit. Runway 26 had no edge lights, no threshold or touchdown zone markings, and a painted width of 75 ft instead of 150 ft. In the cockpit, the heading on both pilots' displays differed by about 40° from the heading bug set for runway 22. Two other regional jets had taxied to runway 22 by the same route that morning, using the same chart, without difficulty. The NTSB found no evidence that the chart discrepancies confused the crew, and concluded that the missing notice to airmen was not a factor.

Why the crew did not use them

The NTSB found that the crew's nonpertinent conversation during taxi broke the sterile cockpit rule of 14 CFR 121.542 and Comair's procedures, which define taxi as a critical phase of flight, and likely contributed to the loss of positional awareness. The captain's repeated "at your leisure", his abbreviated taxi briefing and the conversation reflected a casual atmosphere that, in the Board's words, "most likely created an atmosphere in the cockpit that enabled the crew's errors". It cited airline safety audit data showing that crews who intentionally deviate from procedures are three times more likely to commit other errors.

Once the aircraft was at the runway 26 hold short line, confirmation bias took over. Runway markings lay ahead, the angle from the hold line to runway 26 was the same as the angle from the old taxiway to runway 22, and a lead-on line ran from the taxiway onto runway 26. The first officer's earlier remark about lights being out may have prepared the captain for a dark runway. Having reached what they believed was their runway, the pilots gave little weight to contradicting evidence, including the absence of lights during the roll. The NTSB also found that Comair, like other Part 121 operators, had no procedure requiring crews to verify positively that the aircraft was on the correct departure runway.

Air traffic control

One controller was working both the tower and radar positions. He did not notice the aircraft stop at the wrong hold short line, and after clearing it for take-off he turned to an administrative traffic count instead of watching the departure. The NTSB found that he was most likely fatigued, although the effect of fatigue could not be determined, and that FAA policies at the time did not promote optimal controller monitoring of surface operations. It could not determine whether staffing the shift with one controller, contrary to FAA verbal guidance, contributed.

Runway crossings

Under 14 CFR 91.129(i), a clearance to taxi to a runway allowed an aircraft to cross every runway on the way without a specific clearance. The NTSB had recommended in 2000 that each runway crossing require an explicit clearance, and found that this rule "might result in mistakes that have catastrophic consequences". The FAA's failure to require specific crossing clearances became a contributing factor.

Probable cause and contributing factors

The NTSB determined that the probable cause was "the flight crewmembers' 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 conversation 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."

The Board found the emergency response timely and well coordinated, and attributed the first officer's survival to the prompt arrival of the first responders, their ability to free him from the cockpit wreckage and his rapid transport to hospital.

Safety recommendations and what changed

Runway 26 was closed by notice to airmen on the day of the accident and stayed closed until 1 November 2006, when the new taxiway to runway 22 opened. On 1 September 2006 the FAA issued Safety Alert for Operators 06013, telling crews to confirm, "using the challenge and response technique, that the aircraft is actually positioned on the assigned runway by reference to the heading indicator". On 1 June 2007 FAA Notice N JO 7110.468 required controllers to state the runway number before a take-off clearance and, if the clearance is issued before the aircraft has crossed all intervening runways, to restate the runway to be crossed.

The NTSB issued recommendations during the investigation on runway verification and on lighting guidance for night take-offs (A-06-83, -84), and on controller fatigue and resource management training (A-07-30 to -32, -34). The final report recommended that the FAA:

• require Part 91K, 121 and 135 operators to have all flight deck crew members positively confirm and cross-check the aircraft's location at the assigned departure runway before crossing the hold short line (A-07-44);
• require cockpit moving map displays or an automatic system that alerts pilots to a take-off from a taxiway or the wrong runway (A-07-45);
• require enhanced taxiway centreline markings and surface painted holding position signs at all runway entrances at certificated airports (A-07-46);
• prohibit take-off clearances until the aircraft has crossed all intersecting runways (A-07-47);
• tell controllers to refrain from administrative tasks while aircraft are moving in their area (A-07-48).

It also reiterated its 2000 recommendations that every runway crossing need a specific clearance (A-00-67, -68).

Lessons for pilots

Verify the runway, every time. Before crossing the hold short line and again when lined up, both pilots should confirm the runway from the holding position sign, the runway numbers and markings, the lights, and the heading indicator against the runway heading. A 40° difference between the heading and the bug was on both pilots' displays throughout the take-off roll. See taxiing and runway incursion prevention.

Taxi is a critical phase of flight. The sterile cockpit rule applies from the start of taxi. Nonessential conversation during taxi takes attention from the one task that matters on the ground: knowing exactly where the aircraft is.

Beware confirmation bias. Once a crew believes it has reached the right place, contrary cues are easily explained away. The first officer's "weird with no lights" was such a cue. Treat surprise as a signal to stop and check, and say so aloud. See cognitive biases in decision-making.

Discipline sets the tone. The NTSB found that the crew's deviations from standard procedures most likely created an atmosphere in the cockpit that enabled their errors. Standard briefings, formal checklist calls and closed-loop communication are the defences described in threat and error management and crew resource management.

Know the performance margin. The aircraft needed more runway to reach V1 than runway 26 offered. Knowing the take-off distance required for the day, and roughly what the assigned runway looks like, turns an unexpectedly short or dark runway into an immediate warning.

Crash Investigations pages summarise official investigation reports for study and exam preparation. The investigating body's report is the authoritative account and prevails wherever it differs from this page. Under ICAO Annex 13, an investigation exists to prevent accidents, not to apportion blame or liability.