Incident
During a flight, the cockpit crew received a Traffic Alert and Collision Avoidance System (TCAS) traffic advisory, followed by an aural resolution advisory (RA) instructing them to "CLIMB, CLIMB." The first officer disconnected the autopilot and initiated a climb at a rate of 1,500 feet per minute. Shortly thereafter, the captain announced he was taking control and pitched the airplane to a greater angle. As the airplane ascended, a flight attendant fell to the floor and sustained a broken ankle.
Response
After the TCAS announced "clear of conflict," the captain leveled the airplane at 30,000 feet. He then returned control to the first officer, and the airplane descended back to its assigned altitude of FL 290. A review of radar data and air traffic control information revealed that the accident airplane was climbing at 2,500 feet per minute with an airspeed of 483 knots. The aircraft that triggered the traffic alert was an MD-80 climbing at 2,000 feet per minute with an airspeed of 433 knots. The closest proximity between the two aircraft was 1.54 nautical miles and 1,500 feet vertical separation.
Performance Analysis
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, requiring a response within 5 seconds using approximately a 0.25g maneuver. However, performance analysis of radar data showed that the flight crew's maneuver included a 1,000-foot climb, immediately followed by a descent back to the assigned altitude. This sequence involved an initial 1.15g pull-up to start the climb, a 0.05g push-over to arrest the climb and begin the descent, and a 1.4g pull-up to level off. The time between the 0.05g push-over and the 1.4g level-off was about 5 seconds.