Incident Overview
On 2 November 2007 at 1242Z, an Airbus A340-600, registration ZS-SNG, was involved in an incident at Cape Town International Aerodrome. The aircraft was operating a scheduled domestic flight from Johannesburg to Cape Town, carrying 17 crew members and 306 passengers. The weather conditions were fine with a surface wind of 290°/20kt, temperature 22°C, and visibility greater than 10 km.
Sequence of Events
The flight to Cape Town was routine, cruising at Flight Level 370 (37,000 feet AMSL). The descent and approach were uneventful. The crew was cleared for a right-hand visual approach onto Runway 01. The aircraft was stable at 1,500 feet AGL, and touchdown was normal with a surface wind of 300° at 20 knots.
After touchdown, while decelerating through approximately 70 knots, air traffic control instructed the crew to vacate Runway 01 by turning right onto Runway 16, then proceed to the threshold of Runway 34 and turn right onto taxiway Lima. This instruction was issued because taxiway Alpha One (A1) was closed due to construction, a fact noted in NOTAM A2927/07 and on the DATIS.
The aircraft was brought to a stop on Runway 01 shortly after beginning the right turn. The crew noticed that the engine thrust reversers were not stowed; they were stowed by the cockpit crew, and power was applied to continue the turn and taxi. During the turn, the nose wheel started scuffing on the asphalt, having been deflected to its maximum allowable angle of 76° to the right. The first officer advised the pilot-in-command to stop the aircraft, repeating this approximately five times. However, the aircraft departed the paved runway surface to the left before it could be halted. The nose landing gear assembly sank into soft sand next to the runway, and the aircraft came to a stop 22 meters further on. The crew informed ATC, leading to the aerodrome being closed until the aircraft was recovered about 2½ hours later.
Passengers disembarked via door 2R after mobile stairs were brought to the aircraft. No one was injured. The incident occurred in daylight with fine weather; the runway surface was dry, and the required turn radius was 150°.
Probable Cause
The pilot-in-command, who was also the flying pilot, applied incorrect taxi technique when executing the 150° turn to vacate Runway 01. This caused the nose wheels to skid and scuff on the runway surface. With an increase in speed during the turn, the turn radius of the aircraft was exceeded, and the nose wheel departed the runway surface.