What happened
On 18 July 2006, an Airbus A321, registration TC-OAN, was performing a commercial landing at Rotterdam Airport (EHRD) following a flight from Antalya, Turkey. The aircraft, carrying 146 passengers and seven crew members, was executing a manual VOR-DME approach to runway 06. During the final stages of the approach, the aircraft experienced a significant loss of airspeed. In an attempt to compensate for the decaying speed, the pilot flying increased the aircraft's pitch attitude. However, the lack of sufficient engine thrust caused the aircraft to descend rapidly, resulting in the aircraft touching down approximately 120 meters before the runway threshold. This impact caused the aircraft's tail to strike the paved surface, resulting in substantial damage to the empennage. There were no injuries among the 146 passengers or the crew.
The investigation
The investigation focused on the failure of the auto thrust system to respond to the increasing pitch attitude. While the aircraft's weight and distribution were found to be within limits, maintenance records revealed a history of five previous complaints regarding the auto thrust system's inability to maintain target speeds. Although the airline's technical department had performed various remedial actions, the underlying issue persisted.
Investigators discovered that the aircraft was being operated under the Minimum Equipment List (MEL) with a deferred defect. According to the MEL, the auto thrust system's unserviceability required a specific placard to be placed over the cockpit switch to alert the crew. This placard was missing. Furthermore, the maintenance logbook contained a confusing entry stating the aircraft had "no CAT III capability," which the captain believed meant the system was functional for non-precision approaches. The investigation also noted that the first officer did not intervene or alert the captain to the decreasing airspeed during the approach.
Findings
- The primary cause of the tail strike was the failure of the auto thrust system to increase engine power in response to the pilot's pitch input, which led to increased drag and a subsequent loss of altitude and speed.
- A critical contributing factor was the absence of a required cockpit placard notifying the crew that the auto thrust system was unserviceable.
- Inaccurate or ambiguous maintenance documentation regarding the aircraft's CAT III capability likely misled the flight crew regarding the operational limitations of the aircraft.
- Post-accident technical inspections identified that all three angle of attack vanes were operating out of limits, which was the root cause of the speed fluctuations.
Safety action
Following the incident, extensive testing was conducted by both Airbus and the operator. The aircraft underwent significant repairs, including the replacement of the angle of attack vanes and various other components. To prevent future occurrences, the operator installed additional memory cards in the aircraft to facilitate better data analysis in the event of future speed-related anomalies.