What aircraft was involved and where did it happen?

The accident on 1994-01-21 involved a Terrace, British Columbia, operated by Air BC British Aerospace BAe 146-200 C-FBAB, at CA.

What was the probable cause of the accident?

The aircraft overran the runway because the crew performed an unstabilized approach on a contaminated surface while relying on unreliable braking performance data that lacked a standard safety margin.

BAe 146 Overruns Runway at Terrace Airport

A British Aerospace BAe 146-200 operated by Air BC overran the runway at Terrace, British Columbia, due to an unstabilized approach and unreliable braking performance data.

What happened

On a scheduled flight from Vancouver to Terrace, British Columbia, a BAe 146-200 operated by Air BC encountered challenging weather conditions including low clouds, freezing drizzle, and light snow. While attempting a landing on runway 15, the crew performed a left-hand circling approach through a narrow valley. Due to the low visibility, the crew had to maneuver around clouds, resulting in an unstabilized approach.

The aircraft touched down approximately 1,650 feet beyond the runway threshold. Despite the application of brakes and spoilers, the aircraft failed to decelerate sufficiently on the contaminated, ice-covered surface. The aircraft continued down the runway and exited the paved surface at approximately 25 knots, coming to rest 315 feet into the overrun area. There were no injuries among the 12 passengers or 4 crew members, and the aircraft sustained no damage.

The investigation

The investigation focused on the crew's landing distance calculations and the reliability of the James Brake Index (JBI) tables. Investigators found that the crew relied on JBI tables to estimate the required landing field length, which suggested a safe landing was possible on the 6,000-foot runway. However, these tables do not include the standard 60 per cent safety margin used for dry runways.

Furthermore, the investigation examined the discrepancy between the operator's performance tables and those provided by the manufacturer. It was also noted that the JBI measurements, taken 30 feet from the centerline, may not have accurately reflected the even more slippery conditions present at the center of the runway. The investigation also looked into the crew's decision-making, noting that while the captain expressed doubts and suggested a go-around, the co-pilot continued the approach due to concerns about losing visual contact with the runway.

Findings

The crew conducted an unstabilized approach in a narrow valley under marginal weather conditions.
The crew relied unduly on inaccurate JBI tables that lacked a necessary safety margin.
A tailwind component and a downslope runway contributed to the extended landing roll.
The company used landing performance tables that differed from the manufacturer's specifications for contaminated runways.
The JBI tables provided insufficient warning that the 60 per cent safety factor was absent during low braking action conditions.