On 13 October 2010, a Boeing 717-200 (717),
registered VH-NXD, was being operated by Cobham Aviation Services
Australia, on a scheduled passenger flight from Perth to
Kalgoorlie, Western Australia. On board were 97 passengers, three
cabin crew and two flight crew.
During the approach to land on runway 29 at
Kalgoorlie Airport, the stickshaker activated. The copilot, who was
the pilot flying, reduced the aircraft's pitch angle and continued
the turn onto final. About a minute later, the approach was no
longer stabilised and the flight crew conducted a go-around. On the
second approach to land and after turning onto final, the copilot
noted that the aircraft was below the required profile. As the
copilot increased the aircraft's pitch attitude, the stickshaker
activated for about 2 seconds. Following recovery actions, a
go-around was conducted. The third approach was conducted by the
pilot in command at an airspeed that was about 15 kts higher than
the previous approaches.
The investigation found that the stickshaker
activations were primarily a result of an incorrect approach speed.
The approach speed generated by the flight management system (FMS)
was based on a landing weight that was 9,415 kg less than the
aircraft's actual weight. Prior to departure, the flight crew had
inadvertently entered the aircraft's operating weight in lieu of
the aircraft's zero fuel weight (ZFW) into the FMS. The data entry
error also influenced the aircraft's take-off weight (TOW) in the
FMS. The error went unnoticed and did not manifest as an
operational problem until the approach into Kalgoorlie.
The investigation identified several organisational
issues that had the potential to adversely affect the safety of
future operations. Those issues related to the format of the
aircraft load sheet, the verification check by the flight crew of
the TOW against the load sheet and the lack of an independent
validation check of the FMS-generated landing weight. In response,
the operator has made a number of enhancements to the format of the
717 load sheet, the FMS weight data entry and verification
procedures, the weight validation checks and the 717 simulator
training in respect of recovery from stickshaker activation.
The application of correct operating data is a foundational and
critical element of flight safety. In January 2011, the ATSB
released a research report titled
Take-off performance calculation and entry errors: A global
perspective.
