The Transportation Safety Board of Canada (TSB) determined that the continuation of an unstable approach following a loss of visual reference led to a Jazz Aviation LP aircraft contacting the surface short of the runway at the Sault Ste. Marie Airport, Ontario, in February 2015. There were no injuries, but there was significant damage to the aircraft. The TSB released their investigation report on Thursday.
On Feb. 24, 2015, a de Havilland DHC-8-102, operating as Jazz Aviation LP flight JZA7795 and carrying 15 passengers, departed Toronto/Lester B. Pearson International Airport, Ontario, for a scheduled flight to Sault Ste. Marie Airport, Ontario. While on approach to runway 30, in conditions of twilight and reduced visibility due to blowing snow, the aircraft touched down approximately 450 feet prior to the runway threshold. Following touchdown, the aircraft struck and damaged a runway approach light before coming to a stop approximately 1,500 feet past the threshold.
The investigation determined that a significant power reduction and subsequent decrease in airspeed, while flying below the minimum stabilization height of 500 feet, resulted in an unstable approach. This rapid deceleration steepened the aircraft's vertical path. The crew had reduced power in order to reach the target airspeed for the final approach and landing.
The crew had followed what they understood to be the correct speeds for the approach according to the company's guidance material. “Due to ambiguity in the guidance and uncertainty as to the required speed during the approach, the flight crew did not recognize that the approach was unstable and continued the approach to a landing,” TSB said in a press release Thursday.
The investigation also found that the rapidly changing weather decreased the flight crew's visibility of the runway, and that the steepened vertical profile created as a result of the power reduction went unnoticed, and uncorrected. Although the loss of visual reference required a go-around, the flight crew continued the approach.
An examination of over 500 similar flights on Jazz DHC-8-102s showed that company aircraft routinely fly decelerating approaches below the minimum stabilization height of 500 feet. If approaches that require excessive deceleration below established stabilization heights are routinely flown, then there is a continued risk of an approach or landing accident.
Following the occurrence, Jazz Aviation LP undertook a number of safety actions such as making amendments to the Jazz DASH 8 Aircraft Operating Manual, by introducing significant changes to the "Stabilized Approach Factors" subsection and adding simulator scenarios to the training syllabus.
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