What happened
On 25 November 2004, a Cessna 550 Citation, registration G-FCDB, was performing a passenger flight from Teesside Airport to Copenhagen. During the takeoff roll on Runway 23, the crew experienced a sudden bump and a noticeable yaw to the right at approximately 70 knots. The co-pilot noted the sight of an animal running toward the aircraft, though no remains were found during a subsequent search.
In response to the yaw, the commander applied rudder to correct the aircraft's direction. During the maneuver, the aircraft moved toward the edge of the runway, partially leaving the paved surface to cross a grass area between the dispersal area and a disused section of Runway 01/19. As the right wheel encountered the soft grass, the nose wheel also left the pavement. The commander applied differential braking and increased power to the right engine to regain the runway, eventually taxiing the aircraft back to the apron safely. There were no injuries and no damage to the aircraft.
The investigation
The AAIB examined the flight data recorder, aircraft engineering records, and site markings. While the crew reported a significant yaw, the flight data recorder showed much smaller heading deviations, ranging from 2° to 15°. The data indicated that the aircraft's accelerations were consistent with traveling over an unprepared surface.
Investigators analyzed tyre marks on the ground, which showed the aircraft's path entering the grass and crossing the disused runway. The investigation also considered the cockpit's visibility of ground markings. Although the commander believed the runway lacked centerline lights, the investigation confirmed that such lighting was present. The analysis suggested that the aircraft was likely lined up on the runway edge line rather than the centerline at the start of the takeoff roll.
Findings
- The aircraft was likely lined up on the runway edge line instead of the centerline.
- The initial rightward yaw was likely caused by the drag of the right main wheel as it encountered the grass, potentially exacerbated by hitting a drain cover or the edge of the disused runway.
- The crew's perception of a more severe yaw was likely an unconscious attempt to rationalize the sudden movement and the aircraft's departure from the pavement.
- The lack of ground markings in the dispersal area to indicate it was not part of the usable runway contributed to the error.
Safety action
Following the incident, the airport operator scheduled a review of the ground markings for Runway 23 as part of a refurbishment programme. Additionally, an upgrade to the airfield ground lighting system was planned for mid-2005.