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| CHINA AIRLINES AIRBUS A330-302 B-18305 (MSN 0671) |
China Airlines Flight 140 was a regularly scheduled passenger flight from Taipei-Chiang Kai Shek International Airport (TPE/RCTP), Taiwan to Nagoya-Komaki International Airport (NGO/RJNN), Japan
On the 26th of April 1994, the Airbus A300B4-622R was completing a routine flight and approach, when, just seconds before landing at Nagoya Airport, the takeoff/go-around setting (TO/GA) was inadvertently triggered. The pilots attempted to pitch the aircraft down while the autopilot, which was not disabled, was pitching the aircraft up. The aircraft ultimately stalled and crashed into the ground, killing 264 of the 271 people on board.
Passing through approximately 700 feet, the autopilot was disengaged but the THS remained at its last commanded position of -12.3 degrees. Also at this time, due to the thrust reduction commanded by the first officer, the airspeed decreased to a low level, resulting in an increasing angle of attack (also termed alpha, or AOA). As a result, the automatic alpha floor function of the aircraft was activated, causing an increase in thrust and a further pitch-up. The alpha floor function of the A300 is an AOA protection feature intended to prevent excessive angles of attack during normal operations. Because of the greater size of the THS relative to the elevator (approximately three times greater in terms of surface area), the available elevator control power or authority was overcome as the aircraft neared 570 feet on the approach. Upon hearing the first officer report that he could not push the nose further down and that the throttles had latched (alpha floor function engaged), the captain took over the controls unaware of the THS position.
It was nighttime and Nagoya airport weather at the time was reported as winds from 280 degrees at 8 knots, visibility of 20 kilometers, cumulus clouds at 3,000 feet and a temperature of 20 degrees Celsius. During the initial phase of the approach, both autopilot systems (AP1 and AP2) were engaged as well as the auto throttles. After passing the ILS outer marker and receiving landing clearance, the first officer, who was the pilot flying, disengaged the autopilot system and continued the ILS approach manually.
When passing through approximately 1,000 feet on the approach glidepath, the first officer inadvertently triggered the GO levers placing the auto throttles into go-around mode, which led to an increase in thrust. This increase in thrust caused the aircraft to level off at approximately 1,040 feet for 15 seconds and resulted in the flight path becoming high relative to the ILS glideslope. The captain recognised that the GO lever had been triggered and instructed the first officer to disengage it and correct the flight path down to the desired glide slope. While manually trying to correct the glide path with forward yoke, the first officer engaged the autopilot, causing it to be engaged in the go-around mode as well. As he manually attempted to recapture the glide slope from above by reducing thrust and pushing the yoke forward, he was providing pitch inputs to the elevator that were opposite the autopilot commands to the Trimmable Horizontal Stabiliser (THS), which was attempting to command pitch up for a go around.
Passing through approximately 700 feet, the autopilot was disengaged but the THS remained at its last commanded position of -12.3 degrees. Also at this time, due to the thrust reduction commanded by the first officer, the airspeed decreased to a low level, resulting in an increasing angle of attack (also termed alpha, or AOA). As a result, the automatic alpha floor function of the aircraft was activated, causing an increase in thrust and a further pitch-up. The alpha floor function of the A300 is an AOA protection feature intended to prevent excessive angles of attack during normal operations. Because of the greater size of the THS relative to the elevator (approximately three times greater in terms of surface area), the available elevator control power or authority was overcome as the aircraft neared 570 feet on the approach. Upon hearing the first officer report that he could not push the nose further down and that the throttles had latched (alpha floor function engaged), the captain took over the controls unaware of the THS position.
Aircraft Information:
Airline: China Airlines
Code: CI/CAL
Aircraft: Airbus A300B4-622R
Registration: B-1816
Serial Number: 580
Engines: 2 Pratt & Whitney PW4158
First Flew: 30/10/1990
Sending thoughts and prayers to the families and friends as they remember their loved ones today.
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