What happened
On 30 January 2003, an Embraer 135, registration SE-RAA, was performing a scheduled passenger flight from Aberdeen to Norwich. During the approach, the crew experienced several changing conditions, including an Engine Indication and Crew Alerting System (EICAS) Stall Protection System warning caused by ice accretion, which necessitated an increase in approach speed. Although the crew had been briefed on a wet runway, they did not fully process updated information from Air Traffic Control regarding a significant increase in wind speed and the presence of slush and hail on the runway.
Upon touchdown, the aircraft experienced a significant float, contacting the runway between 50 and 600 metres from the threshold. The aircraft encountered aquaplaning, and the crew reported a total loss of braking effectiveness. Despite applying both the service brakes and the parking brake, the aircraft failed to decelerate sufficiently, eventually exiting the paved surface at a ground speed of 74 kt. The aircraft travelled 130 metres into a snow-covered field before coming to a stop. There were no fatalities and no injuries among the 22 passengers and 3 crew members, though the aircraft sustained minor damage to the landing gear.
The investigation
The AAIB examined the aircraft's flight recorders, which captured data regarding brake pressures and longitudinal acceleration. The investigation established that the aircraft's landing distance required (LDA) had increased due to the tailwind and higher approach speed, exceeding the available runway length. Investigators also reviewed the airport's ATIS procedures and the technical limitations of existing equipment for measuring runway friction in slush. Furthermore, the investigation looked into the airline's policy regarding the use of the 'Flap 22' landing configuration.
Findings
- The crew's arrival briefing was based on outdated ATIS information, leaving them unaware of the true severity of the runway conditions.
- The aircraft overran the runway because the required landing distance exceeded the available runway length due to a tailwind and increased approach speed.
- The use of the Flap 22 configuration, while intended to improve stability, likely contributed to the aircraft's float and delayed touchdown.
- The crew did not fully comprehend multiple ATC transmissions regarding the deteriorating wind and runway state.
- Technical limitations prevented the provision of an accurate braking action report for the slush-covered surface.
Safety action
Following the incident, the airport updated its policy to change ATIS information whenever the runway state changes. The operator amended its landing performance charts, updated procedures for determining approach speeds, and implemented new restrictions on using Flap 22 on short, wet runways. Additionally, the CAA was presented with a recommendation to encourage research into equipment capable of accurately measuring runway braking action under all contamination conditions.