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.
The accident
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.
Investigation
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.
Changes
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.
