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25 July 2021
Report: DHC-8-400 runway excursion, gear collapse after landing on snow-covered runway
The Transportation Safety Board of Canada (TSB) found that limited visual cues due to falling snow and a snow-covered runway contributed to the 2020 runway excursion involving a WestJet Encore DHC-8-402 in Terrace, BC Canada.
On 31 January 2020, a DHC-8-402 aircraft was conducting WestJet Encore flight WEN3107 from Vancouver, BC to Terrace, BC with four crew members and 43 passengers on board. During the landing roll, the aircraft drifted left from the snow-cleared area of the runway and the left main landing gear exited the runway surface, travelling for approximately 400 feet before returning to the runway. During the runway excursion, the aircraft’s nose landing gear collapsed. The aircraft came to a stop in the centre of the runway. The passengers were transported to the airport terminal by bus approximately 30 minutes after landing. No injuries were reported. The damage to the aircraft included the collapsed nose landing gear and damaged right propeller blades.
The investigation found that, given the falling snow and the snow-covered runway, there were limited visual cues available to the flight crew, which decreased their ability to accurately judge the aircraft’s lateral position once it was beyond the runway threshold. Snow clearing operations cleared the centre 100 feet of the runway, which resulted in windrows that were approximately 18 inches high along the edges of the cleared area. This reduced the pilot’s lateral maneuvering room during the landing.
It was also determined that the aircraft initially touched down 10 feet left of the centreline due to control inputs and variable wind conditions and, while the aircraft was still in a light weight-on-wheels condition, a gust contributed to a further deviation to the left until the left main landing gear came into contact with the windrow. As a result, the aircraft was pulled to the left and travelled through the uncleared portion of the runway. During the runway excursion, snow and ice became packed in the nose landing gear bay and caused structural deformation. Consequently, the nose landing gear was no longer being held in place and collapsed rearward into the fuselage, causing substantial damage to the aircraft.
Finally, the investigation also determined that, if aircraft operators do not provide pilots with all the possible tools and relevant information to assess runway suitability for landing, pilots may not evaluate all potential threats and may make decisions based on incomplete or conflicting information.
Pilot uncontactable for 40 minutes fell asleep due to fatigue exacerbated by mild hypoxia
A pilot who overflew their destination and was unresponsive to air traffic control calls for 40 minutes had fallen asleep due to fatigue likely exacerbated by mild hypoxia from the intermittent use of supplemental oxygen, a new ATSB investigation has found.
The pilot was conducting a ferry flight of a Cessna 208B Grand Caravan aircraft from Cairns to Redcliffe, Australia on the afternoon of 2 July 2020. While cruising at 10,000 feet the pilot encountered unforecast icing conditions and poor visibility due to cloud and climbed to 11,000 feet and began using the aircraft’s supplemental oxygen system intermittently. (Pilots are required to continuously use supplemental oxygen when flying unpressurised aircraft, such as the Caravan, when flying above 10,000 feet.)
When the aircraft was about 53 km west-north-west of Sunshine Coast Airport, air traffic control (ATC) unsuccessfully attempted to contact the pilot regarding their planned descent into Redcliffe, the investigation notes.
Following repeated calls to the pilot, ATC enlisted the assistance of pilots in nearby aircraft to contact the Caravan pilot, who was seen to overfly Redcliffe and track towards Brisbane.
The pilot of a Royal Flying Doctor Service Beechcraft B200 King Air aircraft departing Brisbane was asked by ATC to intercept and contact the Caravan pilot, but their initial efforts were unsuccessful. The King Air pilot then dipped their wings and approached the Cessna in an attempt to trigger its traffic alert and collision system (TCAS), but the pilot remained unresponsive.
At 5:35 pm, after 40 minutes without contact and when the aircraft was about 111 km south-south-east of the intended destination, the pilot woke and ATC communications were re-established. The pilot was then instructed to land at Gold Coast Airport, where the aircraft landed safely just after 6pm.
The ATSB found that the pilot was likely experiencing a level of fatigue due to inadequate sleep the night before and leading up to the incident. Further, operating at 11,000 feet with intermittent use of supplemental oxygen likely resulted in the pilot experiencing mild hypoxia. This likely exacerbated the pilot’s existing fatigue and contributed to the pilot falling asleep.
Low visibility, blowing snow factors in King Air runway excursion in Canada
In its investigation report, TSB Canada identified the recurring issue of approaches continued in low visibility environments as a contributing factor a Beech King Air runway excursion. The investigation found that the flight crew believed the landing was permitted given the absence of an approach ban, and landed even though the reported ground visibility was below the minimum aerodrome operating visibility.
On 28 April 2020, a Buffalo Airways Ltd. Beechcraft King Air A100 aircraft was conducting a charter flight under instrument flight rules, from the Cambridge Bay Airport, Nunavut to Kugaaruk, Nunavut, with two flight crew members and freight on board. Immediately after touchdown at the Kugaaruk Airport, the aircraft veered to the right and departed from the runway surface. The aircraft came to rest after colliding with a snowbank on the northwest side of the runway. The crew was uninjured and egressed the aircraft via the main cabin door. There was no fire, but the aircraft sustained substantial damage.
The investigation determined that during the later stages of the approach, a crosswind from the left, and the visual effects of blowing snow contributed to the aircraft being aligned with the right side of the runway. The aircraft touched down near the right edge of the runway and, when the right landing gear impacted the deeper snow along the runway edge, the aircraft veered to the right and departed the runway surface.
Approaches to airports north of 60°N latitude are not restricted by ground visibility and, as a result, the flight crew continued the approach when the reported visibility was ¼ statute mile, which is lower than the published advisory visibility of 1¾ statute miles for this approach. The flight crew believed that the lack of an approach ban permitted a landing, and landed at Kugaaruk Airport even though the reported ground visibility was below the minimum aerodrome operating visibility of ½ statute mile.
The rules that govern instrument approaches in Canada are too complex, confusing and ineffective at preventing pilots from conducting approaches that are not allowed, or banned, because they are below the minimum weather limits, TSB stated. In 2020, the TSB issued recommendations A20-01 and A20-02 calling on Transport Canada (TC) to review and simplify operating minima for approaches and landings at Canadian aerodromes and to introduce a mechanism to stop approaches and landings that are actually banned.
In a response to both recommendations, TC stated that it would be forming and leading an industry working group to draft a Notice of Proposed Amendment to update approach ban regulations, as well as the supporting documentation and guidance. Until these recommendations are fully addressed, there remains a risk that flight crews will initiate, or continue, approaches in weather conditions that do not permit a safe landing.
Tailwind landing factor in Boeing 737-800 runway excursion, Canada
In its newly released investigation report the Transportation Safety Board of Canada (TSB) found that changing runways without recalculating the landing distance required based on the changes in wind and runway surface conditions, led to a runway overrun in Halifax, Canada, in 2020.
On 5 January 2020, a WestJet Boeing 737-800 aircraft was conducting flight WJA248 from Toronto/Lester B. Pearson International Airport, Ontario, to Halifax/Stanfield International Airport, Nova Scotia, with 172 passengers and six crew members on board. The flight crew had originally planned to conduct an approach for runway 05. However, due to a lowering ceiling and reduced visibility, the crew requested to change to the runway 14 instrument landing system approach, which allows for landing with lower minimum ceiling and visibility requirements than the approach to runway 05. The aircraft then touched down with a tailwind component on the wet, snow-covered runway. The aircraft could not be stopped and it overran the end of runway 14, coming to rest in snow with the nose wheel approximately 91m beyond the runway end. There were no injuries and no damage to the aircraft.
The investigation found that, while preparing for the runway change, the flight crew mentally assessed that the head wind for Runway 05 would become a crosswind for runway 14. As a result, they did not recalculate the effects of the wind for the approach to runway 14, but rather considered that the landing distance and the target approach speed calculated for Runway 05 were still appropriate. However, the reported wind speed and direction changed as the flight progressed, resulting in a tailwind component that exceeded the operator’s limitation, a lower required approach speed, and a landing distance that exceeded the runway length available. None of this was recognized by the flight crew and, as a result, they continued the approach to runway 14. The unchanged target approach speed combined with the tailwind component resulted in the aircraft touching down at a faster groundspeed, thus requiring a longer stopping distance. The wet snow contamination on the runway reduced braking effectiveness, which also contributed to an increase in landing distance.
Following the occurrence, WestJet highlighted to its pilot group the importance of using the actual runway intended for landing when making pre-landing performance calculations. The company also revised its emergency response checklist to include the requirement to pull the cockpit voice recorder and flight data recorder circuit breakers after an incident, and is now monitoring for landings that exceed the maximum tailwind component in its flight data monitoring program.
Failure to use checklists factor in King Air loss of control accident
The failure of a pilot to control an airplane following the loss of thrust in one of two engines just seconds after takeoff led to the fatal crash of a Beechcraft King Air 350i in Texas, the National Transportation Safety Board said in a report.
The King Air crashed into an aircraft hangar 17 seconds after lifting off a runway at Addison Airport, Addison, Texas, June 30, 2019. The accident killed both pilots and all eight passengers.
The NTSB said in its report that after the left engine lost almost all thrust several seconds after takeoff, the pilot responded to the emergency with left rudder input, the opposite action of what the emergency called for. Seconds later, the pilot applied right rudder but by that point the airplane was rolling inverted, and there was insufficient altitude for recovery.
Investigators determined that had the pilot initially applied right rudder input, the airplane would have been controllable.
The audio from the cockpit voice recorder revealed the pilots did not call for any of the checklists that would typically be used before takeoff, nor did they discuss what they would do in the case of a loss of engine thrust on takeoff or any other emergency procedure. The NTSB said the pilot’s failure to follow checklists and adhere to the airplane manufacturer’s emergency procedures contributed to the accident.
A detailed examination of the left engine and its control systems found no condition that would have prevented normal operation. The NTSB noted that there was a known risk of an unintentional movement of an engine power lever if its friction lock was adjusted incorrectly. Friction lock settings are one of the items in a pre-takeoff checklist the pilot failed to use.
Investigators were unable to determine if the friction lock settings played a role in the loss of thrust on the left engine. The cause for loss of engine thrust could not be determined.