What happened
On 24 January 2004, a Boeing 777-200, registration 9V-SRG, was completing a scheduled passenger flight from Brisbane to Singapore. During the approach to Changi Airport, the crew encountered heavy rain and significant weather disturbances. Although the crew initially planned for an automated landing due to poor visibility, the pilot flying transitioned to a manual landing at approximately 520 feet above the ground.
As the aircraft approached Runway 02L, it encountered rapidly changing wind conditions, including a strong crosswind and a quartering tailwind. The aircraft touched down firmly at 1.6g, approximately 4 meters left of the runway centerline, with the left wing low. Upon impact, the left landing gear skidded across the pavement and onto the adjacent grass verge, traveling roughly 360 meters. The aircraft eventually stabilized and taxied to the gate under its own power. There were no injuries among the 269 occupants.
The investigation
The investigation focused on the interaction between the wind conditions, the runway surface, and the aircraft's behavior during touchdown. Investigators examined flight data recorder (DFDR) records, which showed that the wind speed fluctuated significantly in the seconds leading up to touchdown. The analysis also looked into the drainage capabilities of the runway shoulders and the physical state of the landing gear.
Technical inspections of the 9V-SRX landing gear revealed that all six tires on the left side showed evidence of reverted rubber aquaplaning, with three tires becoming deflated. The excursion caused structural damage to the aircraft, including torn junction boxes and damaged wing-to-body fairings, as well as damage to several runway edge lights.
Findings
- The primary cause of the excursion was reverted rubber aquaplaning triggered by a combination of a wet runway, heavy rain, and a firm touchdown.
- Rapidly changing wind conditions at low altitude made it difficult for the pilot to maintain the correct aircraft attitude and centerline.
- While the runway slopes met international standards, water did not drain quickly enough from the runway shoulders, leading to pooling.
- The decision to switch from an autoland to a manual landing increased the crew's workload during unstable weather conditions.
Safety action
Following the investigation, several recommendations were issued:
- The airline was advised to enhance crew training regarding the hazards of aquaplaning and crosswind landings in heavy rain.
- The airport operator was urged to improve drainage on the shoulders of Runway 02L to prevent water accumulation.
- A recommendation was made to ICAO to review international standards for runway construction to better accommodate airports prone to heavy rainfall.