The Transportation Safety Board of Canada (TSB) found that changing runways without recalculating the landing distance needed, based on the changes in wind and runway surface conditions, led to a runway overrun in Halifax, Nova Scotia, in 2020.
WestJet Flight 248 skidded off the end of a runway at the Halifax Stanfield International Airport on Jan. 5, 2020.
It landed in the midst of a snowstorm and overshot the runway with 172 passengers and seven crew members aboard. There were no injuries.
TSB said the flight crew had originally planned to land on Runway 05, but decided to change runways and landed on Runway 14 instead.
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“(Runway 14) allows for landing with lower minimum ceiling and visibility requirements than the approach to Runway 05,” said TSB in a statement.
Once the aircraft touched the wet, snow-covered runway, it could not be stopped and it overran the end of the runway.
TSB’s investigation found that, while preparing for the runway change, “the flight crew 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, TSB found that the reported wind speed and direction changed as the flight progressed.
“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,” TSB said.
Investigators also noted that the wet snow on the runway reduced braking effectiveness, which also contributed to an increase in landing distance.
From 2005 to 2019, TSB said they have investigated 19 incidents where aircraft overran runways.