US Airways Express Flight LOF3504 Runway Overrun at Ottawa

Incident Overview and Aircraft Details On a wet day, a US Airways Express (Trans States Airlines) Embraer 145LR, registration N829HK, serial number 145281, operating as Flight LOF3504, overran Runway 25 at Ottawa/Macdonald-Cartier International Airport. The aircraft departed Pittsburgh, Pennsylvania, with two flight crew, one flight attendant, and 28 passengers on board. It came to rest approximately 300 feet off the end of the runway in a grass field. There were no injuries, and the aircraft sustained minor damage to the inboard left main landing gear tire. Light rain showers were present at the time of landing. After the rain subsided, passengers were deplaned and bussed to the terminal. The aircraft was not equipped with thrust reversers; it relied on spoilers and wheel-brakes with an anti-skid system for deceleration. All four spoilers deployed automatically on landing, and brakes were applied, but the aircraft did not slow as expected. The captain took control after the pilot flying reported the brakes were not working. The brakes became effective 16 to 19 seconds after weight on wheels, but the aircraft could not be stopped on the runway. No physical signs of skidding or hydroplaning were found on the aircraft or runway after inspection. ## Approach and Landing Sequence The flight from Pittsburgh was uneventful. Approaching Ottawa, the aircraft was radar vectored around storm cells for a localizer back course Runway 25 approach. The aircraft was approximately 1.5 miles north of the Ottawa non-directional beacon (NDB) at 2,000 feet above sea level and 185 knots indicated airspeed when air traffic control issued the instruction for the final turn to intercept the localizer. This resulted in a shortened final approach, as the NDB is only 4.1 nautical miles from the threshold of Runway 25. The aircraft was cleared to land. Although the airspeed was high, the inboard spoilers, which could be deployed in flight as speed brakes, were not extended. While attempting to capture the localizer, the aircraft drifted left and right of the localizer several times until on short final, less than one mile from the threshold. The flight crew had calculated approach speeds as 133 KIAS for a flap 22 approach and 128 KIAS for a flap 45 approach. Because the aircraft was fast and on a high, shortened final approach, the crew prepared for a flap 22 landing. The maximum speed permitted for the flap 22 position is 200 KIAS, and for the flap 45 position, 145 KIAS. At approximately three miles from the threshold and 180 KIAS, the crew lowered the landing gear and selected flap 22. The airspeed decreased to 150 KIAS at one mile, and the aircraft crossed the runway threshold at 140 KIAS, 75 feet above airfield elevation. It then continued for 1,675 feet before reaching 50 feet above airfield elevation. From 50 feet above airfield elevation to weight on wheels, the aircraft travelled approximately 2,125 feet, and the weight on wheels speed was 120 KIAS. The landing, at approximately 1720 eastern daylight time, was smooth with no abnormalities. ## Runway, Weather, and Performance Data Runway 07/25 at Ottawa/Macdonald-Cartier International Airport is 8,000 feet long, 200 feet wide, with a smooth asphalt surface. It was raining at the time of the occurrence, and the runway was wet, but there were no indications of excessive quantities of standing water. The 2100 aviation routine weather report for Ottawa/Macdonald-Cartier International Airport indicated wind 220° True at five knots, visibility 10 miles in light rain showers, overcast cloud layer at 2,100 feet, and an altimeter setting of 29.55. Recent thunderstorms had occurred. The landing weight of the aircraft was estimated to be approximately 41,000 pounds. The reference approach speed for an Embraer 145LR at this weight is 132 knots for flap 22 and 127 knots for flap 45. The Aircraft Flight Manual safety factored landing distance for an aircraft landing weight of 41,000 pounds, with flap 22, landing on a wet runway with winds 230° at 5 knots was 6,500 feet. The Aircraft Flight Manual unfactored landing distance for the same conditions is approximately 3,900 feet. Assuming a typical touchdown target of 1,000 feet from the threshold, this gives an Aircraft Flight Manual-derived ground roll distance of approximately 2,900 feet. The actual ground roll distance of the aircraft, as calculated from flight data recorder data, was approximately 4,500 feet, including the 300-foot overrun. The flight data recorder-derived ground roll exceeded the Aircraft Flight Manual nominal value by 1,600 feet. The flight data recorder data indicated that the distance between the aircraft when it was 50 feet above airfield elevation to when it had come to a stop was 6,625 feet. ## Flight Recorders and Crew The flight data recorder and cockpit voice recorder were sent to the Transportation Safety Board Engineering Branch for analysis. The flight data recorder data indicated that the aircraft was configured for the landing with 22° of flap. Weight on wheels occurred approximately 3,800 feet from the threshold of the runway, and the aircraft travelled a further 4,500 feet before coming to a complete stop. The vertical g data indicated that the touchdown was very smooth. The hydraulic pressure for the braking system was plotted for the incident landing and for the previous two landings, which had been conducted on dry runways. The brake pressure for all three landings started to rise at approximately six seconds after weight on wheels. The flight data recorder records the brake pressures once per second. These records indicate that during the incident landing the brakes were active, although there were indications of low, fluctuating brake pressures, and the pressures did not rise above 500 psi until approximately 16 seconds after weight on wheels for the right brakes and 19 seconds for the left brakes. This rise in brake pressure coincides with an airspeed of approximately 94 KIAS. The pressures continued to rise over the next nine seconds to approximately 2,450 psi for the right brakes and 900 psi for the left brakes, at which point the aircraft left the runway. On the previous two landings, the brakes were active and the pressures rose above 500 psi within the first ten seconds and continued to climb to a maximum of approximately 1,000 psi over the next six seconds, at which point the pressures started to decrease. The occurrence aircraft was not equipped to record individual brake pedal positions, so it was not possible to determine the amount of brake pedal deflection. The longitudinal acceleration trace for the incident landing showed an increase in deceleration from +0.08g to a constant deceleration of approximately 0.08g until 15 seconds after weight on wheels, when the brake pressures started to rise. The deceleration then rose steadily to 0.45g at which point the aircraft left the runway. On the previous landing, the longitudinal deceleration increased to a maximum of approximately 0.20g in the first 16 seconds after weight on wheels, and then started to decrease as the aircraft slowed. While attempting to download the information from the cockpit voice recorder, it was found that the recorded data had been erased. The cockpit voice recorder was taken to the manufacturer's facility in Seattle, and the data was successfully recovered. The cockpit voice recorder showed that 31 seconds before the end of the recording the cockpit voice recorder was powered down; the time recorded on the cockpit voice recorder from the aircraft UTC clock was 21:33:39. The cockpit voice recorder was then powered up again at 21:49:36, erased twice, and then powered down six seconds after the second erase command was completed. Erasure of cockpit voice recorders is prohibited in Canada by Canadian Aviation Regulation 605.34 and in the United States by Federal Aviation Regulation 125.227. In accordance with Transportation Safety Board Regulations, when a reportable accident or incident takes place, the owner, operator, master, and any crew member shall preserve and protect any evidence relative to the reportable accident or incident. The deliberate erasure of a cockpit voice recorder in an attempt to destroy evidence would be an offence punishable on summary conviction. Everyone convicted of such an offence is liable, pursuant to the Criminal Code of Canada, to a fine of not more than $2,000 or to imprisonment for six months or to both. The captain, who was the pilot non-flying, occupied the left seat. He held a valid airline transport pilot licence and had accumulated a total flying time of approximately 8,000 hours, with 4,300 hours on type. The first officer, who was the pilot flying, occupied the right seat. He held a valid commercial pilot licence and had accumulated a total flying time of approximately 1,860 hours, with 900 hours on type. His experience as pilot flying on Embraer aircraft without thrust reversers was limited to approximately five flights. ## Aircraft Configuration The Embraer 145LR is available with or without thrust reversers. At the time of the occurrence, the operator's Embraer fleet consisted of 22 aircraft fitted with thrust reversers and 17 aircraft without thrust reversers. Thrust reversers were not installed on the occurrence aircraft, and the aircraft was stopped using the wheel-brake system and the spoilers. The aircraft was equipped with four spoilers, two on each wing. The two inboard spoilers can be deployed in flight as speed brakes to help slow the aircraft. For this to occur, the aircraft must be configured with the flaps at 0° or 9°, and the thrust lever angles must be below 50°. With weight on wheels, all four spoilers deploy automatically when wheel speed exceeds 25 knots and both engine thrust lever angles are at idle.