Comair Flight 5645

The flight crew received a traffic advisory (TA) alert from the Traffic Alert and Collision Avoidance System (TCAS), followed shortly by an aural resolution advisory (RA) warning to "CLIMB, CLIMB." The first officer (FO) then disconnected the autopilot and initiated a climb, at a rate of ascent of 1,500 feet per minute. The captain then announced he was taking the controls and proceeded to pitch the airplane at a greater angle. As the airplane ascended, the flight attendant fell to the floor and broke her ankle. Once the TCAS announced, "clear of conflict," the captain leveled the airplane at 30,000 feet. He then returned the controls to the FO, and the airplane was descended back to an assigned altitude of FL 290. A review of radar data and air traffic control information, revealed that the accident airplane was climbing at a rate of 2,500 feet per minute and an airspeed of 483 knots. The airplane which caused the traffic alert for the accident airplane was an MD-80, which was climbing at 2,000 feet per minute, and an airspeed of 433 knots. The closest proximity between the two aircraft was 1.54 nautical miles, and 1,500 feet. According to the operator's Flight Standards Manual, "the correct response to a corrective RA is to fly from the red zone into the green zone. This maneuver requires a response within 5 seconds of the advisory using approximately a 0.25g maneuver". A performance review of the radar data revealed the flight crew's maneuver in response to the TCAS alert included a 1,000-foot climb, followed immediately by a descent back to the airplane’s assigned altitude. The maneuver described by the radar data could be performed using an initial 1.15 G pull-up to start the climb, followed by a 0.05 push-over to arrest the climb and start the descent, followed by a 1.4 G pull-up to level the airplane at the assigned altitude. In this sequence, the time between the 0.05 G push-over and the 1.4 G level-off was about 5 seconds.

Verbatim NTSB analysis and probable cause from the NTSB dataset