History of the Flight
On 24 March 2010, Cargojet flight 620, a Boeing 727-225 (registration C-GCJZ), departed Hamilton/John Munro International Airport, Ontario, at 0120 Atlantic Daylight Time on a scheduled cargo flight to Greater Moncton International Airport, New Brunswick, with three crew members aboard. Pre-flight preparations noted gusting winds and light rain at Moncton. En route, the crew obtained ATIS information Bravo and consulted landing distance charts. They decided to conduct an Instrument Landing System (ILS) approach to Runway 06.
Approach and Landing
At 0303:57, prior to glideslope intercept, the aircraft was cleared to land on Runway 06. The reported surface winds were 8 knots gusting to 17 knots. The autopilot captured the glideslope and localizer, but shortly thereafter the captain, as pilot flying, disengaged the autopilot and manually flew the approach. The aircraft briefly deviated above the glideslope, exceeding one dot, but was corrected after standard callouts. Crossing the final approach fix, the aircraft was approximately 50 feet higher than the published glideslope check altitude. It re-established on the glideslope and remained on it until the threshold.
Approximately 2 nautical miles from the threshold, Runway 06 became visible. The aircraft encountered heavy rain descending through 600 feet above sea level. Threshold crossing was at 165 knots indicated airspeed. Touchdown occurred between 2000 and 2500 feet from the threshold at approximately 157 knots. The average rate of descent from threshold to touchdown was about 400 feet per minute. The heading at touchdown was 2.2 degrees less than the runway heading.
Runway Overrun
After touchdown, automatic speed brakes deployed. Reverse thrust was selected approximately 3 seconds later. The aircraft began to veer right, and reverse thrust was reduced then re-applied. Maximum manual wheel braking was maintained throughout the landing roll. The crew was unable to stop the aircraft before the runway end. The aircraft passed through the 60-metre paved runway end strip and departed the paved surface at about 50 knots indicated airspeed. It came to rest in deep mud approximately 27 seconds after touchdown, with the nose wheel about 340 feet beyond the runway end and 140 feet beyond the paved strip. Local firefighters arrived about 20 minutes after the aircraft left the runway, and the crew exited using a ladder provided by them. There were no injuries, and the aircraft sustained minor damage.
Operational Considerations
The captain chose Runway 06 for landing because of wind direction and the availability of a precision approach, believing sufficient landing distance was available. However, Runway 11 offered an additional 2000 feet of landing distance and was within crosswind limits. The flight crew were not accustomed to landing on the shorter Runway 06. The captain elected to carry out a pilot-flown approach, as weather was above the mandatory pilot-monitored approach limits. The heavy rain likely focused both pilots' attention on the runway, causing the excessive airspeed to go undetected.
Landing Performance
Boeing's Airplane Flight Manual factored wet runway landing distance for the aircraft weight was 5990 feet, within dispatch limits for wet Runway 06 but representing over 97% of the available landing distance. The factored distance included a 15% safety buffer; the unfactored wet distance was 5209 feet. The combination of a delayed touchdown point, higher than required touchdown speed, slight downsloping runway, and standing water on the runway eroded the safety margin, leaving insufficient runway to stop. Current Canadian regulations (CAR 705) do not require the use of actual contaminated landing distance data for dispatch, and there is no requirement to calculate a landing performance safety margin before commencing an approach. Previous studies have indicated that a wet runway dispatch factor greater than 2.2 (compared to the existing factor) may be necessary for adequate safety on wet un-grooved runways.