United Express Flight 3363 Runway Excursion at Ottawa/Macdonald-Cartier International Airport

Incident Overview and Immediate Aftermath On 1529 Eastern Daylight Time, an Embraer EMB-145LR with registration N840HK and serial number 145341, operating as United Express Flight 3363 for Trans States Airlines LLC, landed on Runway 32 at Ottawa/Macdonald-Cartier International Airport (CYOW) in heavy rain. Shortly after touchdown, the aircraft skidded off the left side of the runway. The incident resulted in no injuries to the 44 passengers and 3 crew members aboard, all of whom evacuated safely using the main cabin door. The runway excursion caused both sides of the main landing gear to collapse, damaging the wing and causing a fuel leak. No fire occurred, and the emergency locator transmitter did not activate. ## Flight History and Approach United Express Flight 3363 departed Chicago O'Hare International Airport at 1406. Before descending into CYOW, the flight crew obtained ATIS information Yankee issued at 1411 and calculated an approach speed (V APP) of 133 knots indicated airspeed (KIAS) based on reported wind conditions. Although Runway 25 was the active runway, Trans States Airlines prohibited operations on Runway 07/25 when the surface was damp or wet due to a previous overrun in August 2010. With rain showers forecast and Runway 32 being the longest runway, the crew decided at 1506 to conduct an instrument landing system (ILS) approach to Runway 32. At 1524, the CYOW terminal air traffic controller advised the crew that heavy rain had started. Approximately two minutes later, the aircraft intercepted the glideslope for Runway 32. The final descent began with landing gear extended and flaps set to 22°. The tower controller reported moderate rain and wind from 310° magnetic at 10 knots. The aircraft crossed the GREELY final approach fix at 4.3 nautical miles, slightly above the glideslope at 174 KIAS. Around 1528, the aircraft passed through 1,000 feet above ground level at 155 knots, and flaps were selected to 45° at approximately 145 KIAS. The tower then advised that wind had changed to 320°M at 13 knots gusting to 20 knots, prompting the crew to increase V APP to 140 KIAS. ## Touchdown and Runway Excursion At 1529, the aircraft crossed the Runway 32 threshold at approximately 45 feet above ground level at 139 KIAS. As rain intensity increased, the crew selected windshield wipers to high. Engine power was reduced and a flare commenced at about 20 feet above ground level. Just before touchdown, a downpour obscured the crew's view of the runway. Perceiving a sudden increase in descent rate at approximately 5 feet above ground level, the captain applied maximum thrust on both engines. The master caution light illuminated, and a voice warning indicated the flaps were not in a take-off configuration. Maximum thrust was maintained for 7 seconds. The aircraft touched down smoothly 2,700 feet beyond the threshold at 119 KIAS, with airspeed increasing and the aircraft becoming airborne again. A second touchdown occurred at 3,037 feet beyond the threshold, with airspeed increasing through 125 KIAS. Airspeed peaked at 128 KIAS as the nosewheel lowered to the ground, after which thrust levers were retarded to flight idle. The outboard spoilers deployed almost immediately, and inboard spoilers deployed about 8 seconds later. The aircraft was approximately 20 feet right of the runway centerline at the second touchdown. Once the nosewheel was on the ground, the captain applied maximum brakes. The crew immediately noted the aircraft began skidding, and the captain requested the first officer to apply maximum brakes as well. The aircraft continued to skid, with no significant brake pressure recorded until about 14 seconds after outboard spoiler deployment, when brake pressure suddenly increased to maximum. During this time, the captain attempted to steer the aircraft back to the runway centerline. As the aircraft skidded, it began yawing to the left. Full right rudder was applied but was ineffective in correcting the left yaw. ## Contributing Factors and Analysis Investigation found no indication that an aircraft system malfunction contributed to the occurrence, nor that flight crew performance was degraded by physiological factors such as fatigue. The analysis focused on operational factors, environmental conditions, and aircraft-related systems. The flight crew had calculated a reference speed (V REF) of 128 KIAS and a target approach speed (V APP) of 133 KIAS. The aircraft crossed the GREELY final approach fix slightly above the glideslope at approximately 1,470 feet above ground level with landing gear extended, flaps at 22°, and a speed of 174 KIAS, which was 41 KIAS above V APP. The approach was flown at speeds exceeding Trans States Airlines-recommended approach speeds. Both the TSA General Operating Manual and standard operating procedures specify that the aircraft must be stabilized and configured at not less than 1,000 feet above ground level. Per TSA standard operating procedures, the pilot monitoring is required to call out deviations from standards during the approach. The procedures state that a missed approach must be conducted if airspeed exceeds ±5 knots or if the aircraft is not properly configured below the stabilized approach height of 1,000 feet above ground level. No callouts regarding speed deviations below the minimum stabilized approach height were verbalized by the pilot monitoring during the approach. When approaching Runway 32, the 1,000 feet above ground level height is reached at approximately 2.9 nautical miles final. At this point, the landing gear was down, but the aircraft configuration was flaps 22° and airspeed 155 KIAS, instead of the required flap 45° and V APP airspeed of 133 KIAS. Flap 45° was selected at 2.3 nautical miles final, at 800 feet above ground level. When advised of updated wind conditions at 2 nautical miles final, the crew recalculated and increased V APP to 140 KIAS. The aircraft crossed the threshold at 139 KIAS, 11 knots above V REF. Immediately before touchdown at about 5 feet above ground level, the captain selected maximum thrust on the engines. This action increased airspeed and extended the flare to a touchdown point at 3,037 feet, which was 1,537 feet beyond the TSA-recommended maximum touchdown zone of 800 to 1,500 feet beyond the runway threshold. The combination of excessive airspeed crossing the runway threshold and a delayed touchdown point significantly decreased the distance available to safely stop the aircraft. The proper landing technique described in TSA standard operating procedures for landing on a wet runway is a firm landing at the recommended speed and within the specified touchdown zone. This technique ensures tires break through the film of water on the runway, providing positive spin-up of the wheels to ensure the anti-skid brake system and spoiler system operate properly. The approach and landing technique used in this occurrence was unchanged from the technique normally used for all landings performed by the captain, which increased the likelihood that the wheels would not break through the film of water on the runway. After touchdown, the captain used a steady and firm application of brakes, which is the recommended technique for best braking effectiveness. The captain assessed that the aircraft was not decelerating as expected and elected to engage the emergency/parking brake (EPB), contrary to TSA standard operating procedures. Activation of the EPB on the wet runway slowed main tire rotation, disabling the anti-skid braking system and prolonging the skid. TSA standard operating procedures state that attempting to modulate brakes while the anti-skid is operating should generally be avoided unless required to maintain directional control. These instructions suggest that during a situation involving loss of directional control during hydroplaning, modulating the brakes (release and reapply) is an acceptable method. ## Environmental Conditions and Hydroplaning It had been raining for 10 minutes before the occurrence. During the approach, rain became heavy at CYOW. The International Civil Aviation Organization's definition of a contaminated runway refers to a water depth of more than 3 mm. The estimated depth of water on Runway 32 at the time of landing was 4–6 mm, which equates to a contaminated runway according to the ICAO definition. Dynamic hydroplaning is usually associated with heavy rain showers and can be induced with as little as 2.54 mm of water on the runway surface. In this occurrence, a heavy rain shower just before the landing resulted in a water depth on Runway 32 conducive to hydroplaning. After the captain applied the brakes, the aircraft began to skid. Brake application was maintained throughout the landing roll until the aircraft stopped. Steam-cleaned marks were noted at various locations along the runway, and all four main landing gear tires exhibited patches of reverted rubber. The tires had angular cuts across these patches, consistent with all four wheels being locked when the aircraft departed the runway surface. This sign indicates the aircraft experienced hydroplaning almost immediately after landing and periodically throughout the landing roll. The presence of water on the runway caused the aircraft to hydroplane, leading to a loss of directional control and braking ability. This condition was exacerbated at some time during the landing roll because the EPB was applied. Three of the four main tires were underinflated, which lowered their hydroplaning speed. When landing on a wet runway with underinflated tires, there is an increased risk of hydroplaning and possible runway excursion. ## Wing Spoiler System Almost immediately after landing, the outboard spoilers deployed, indicating the speed of either the number 2 or number 4 wheel (or both) was greater than 25 knots. About 20 seconds later, the outboard spoilers retracted, indicating the speed of both wheels had dropped below 25 knots. The inboard spoilers deployed about 8 seconds after the outboard spoilers. The aircraft experienced hydroplaning almost immediately, and hydroplaning would prevent or delay the wheels from spinning up. Since no discrepancies were noted with the spoiler system components, it is likely that the number 1 and number 3 wheel speeds were below 25 knots for about 9 seconds after touchdown. The inboard spoilers retracted within about 4 seconds, indicating the spe