New York, NY, USA
N173AN
Boeing 757
The airplane was descending toward the destination airport with the autopilot and autothrottle systems engaged. As the airplane was approaching 12,000 ft, and the autopilot was capturing the altitude, the captain adjusted the altimeter resulting in a displayed altitude of 12,100 ft. The captain (the pilot flying) selected flight level change mode on the autopilot to recapture the altitude and set the speed at 250 knots to slow from about 255 knots. As a result, the autothrottles went to Throttle Hold mode when the throttle levers reached the aft stop. As the captain was briefing the approach, the airplane slowed and pitched up as it tried to maintain altitude with a reduced throttle setting. An international relief officer who was in the cockpit at the time commented on the airplane’s decreasing speed three times when the airplane’s airspeed was about 186 knots before stating that the captain should push the nose over. The captain disengaged the autopilot and auto throttles, aggressively pitched down, and increased the throttles. These aggressive maneuvers caused the flight attendants in the aft galley to be thrown against the ceiling. One flight attendant sustained a compound arm fracture; two other flight attendants sustained minor injuries. The crew subsequently landed the airplane without further incident.
On September 6, 2018, about 1248 eastern daylight time, American Airlines flight 279, a Boeing 757-223, N173AN, was involved in an in-flight upset during the descent to John F. Kennedy International Airport (JFK), New York, New York. The flight crew subsequently made an uneventful landing. During the event, one flight attendant sustained serious injuries, and two flight attendants sustained minor injuries. The other 110 airplane occupants were not injured, and the airplane was not damaged. The flight was operating under the provisions of Title 14 Code of Federal Regulations Part 121 as a scheduled international passenger flight from Edinburgh Airport, Edinburg, Scotland, to JFK. The captain was the pilot flying during the descent, and the first officer was the pilot monitoring. An international relief officer was in the cockpit jumpseat during the descent. According to crew interviews, flight data recorder (FDR) information, and cockpit voice recorder (CVR) information, the airplane began descending from flight level 240 with the autopilot and auto throttles engaged. At 1245:39, as the aircraft neared 12,000 ft (which had previously been dialed into the mode control panel [MCP]), the autopilot Altitude Hold mode engaged. About 16 seconds later, the recorded altimeter setting changed from 29.92 to 30.13 inches of mercury, resulting in an immediate change to the displayed altitude. The captain reported that the altitude at that time was 12,100 ft. According to the captain, he then selected flight level change (FLCH) on the MCP, and the auto throttle system immediately transitioned to FLCH descent mode to reacquire the desired altitude of 12,000 ft. The captain stated that the MCP speed window displayed an airspeed of about 253-255 knots, which was slightly above the flight crew’s desired airspeed of 250 knots. The MCP speed was then manually moved to 250 knots, which caused both engine throttle lever angles to decrease (indicating the throttles were moving aft and reducing thrust) and the airplane to decelerate. Once the throttles reached the aft stop, the auto throttle system entered the Throttle Hold (THR HOLD) mode. Starting about 1246:23, the captain began briefing the approach. During the briefing, air traffic control cleared the flight to descend to 7,000 ft and, at 1247:22, provided instructions to expedite through 9,000 ft . With the autopilot in FLCH mode, a target altitude of 12,000 ft, and the auto throttles in THR HOLD mode, the airplane’s pitch attitude began to increase (to hold 12,000 ft), and the airspeed started to decay below 250 knots. Between 1247:27 and 1247:32, the international relief officer made three comments about the decreasing speed. At 1247:34, the airspeed was about 186 knots, the throttle lever angles increased rapidly, the auto throttle system exited THR HOLD mode, and both engines’ fan speeds began to increase. At 1247:40, the international relief officer stated loudly, “push. push it over. get the autopilot off. push it over,” because, according to the relief officer, the airspeed was getting “dangerously low.” At 1247:42, the FDR recorded the autopilot and autothrottle systems being disengaged. The throttle lever angles began to decrease, and the airspeed began increasing from 195 knots. Two seconds later, the airplane’s pitch attitude was about 10° nose up, and the control column position moved forward quickly to command nose-down attitude. From 1247:44 to 1247:55, the recorded vertical acceleration varied between 1.476 and -0.156 G, and the pitch attitude varied between 10° nose up and 3° nose down. After the event, the airspeed increased to about 250 knots, the control column position and pitch stabilized, and the autopilot was re-engaged. The airplane then began descending to 7,000 ft, as ATC instructed. The flight crew completed the remainder of the flight uneventfully and landed the airplane at the destination airport about 1701.
The flight crew’s failure to adequately monitor the airplane’s airspeed, which led to the captain’s aggressive control inputs to increase airspeed; these aggressive inputs resulted in injuries to three cabin crewmembers.
Source: NTSB Aviation Accident Database
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