ASN Wikibase Occurrence # 147132
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Narrative:The aircraft was operating in instrument meteorological conditions en route to Melbourne and had accumulated a deposit of ice on the wings and windscreen wipers. The crew interpreted this ice deposit as being less than that required for them to activate the de-ice systems on the wing leading edges, in accordance with the aircraft flight manual procedures. As the aircraft approached Melbourne the crew were instructed to enter a holding pattern at Eildon Weir. The crew acknowledged this instruction and reduced power in order to slow the aircraft to the holding pattern airspeed. The crew subsequently allowed the airspeed to fall below the target speed of 154 knots, and despite remedial action, did not regain the target speed.
|Date:||Wednesday 11 November 1998|
|Fatalities:||Fatalities: 0 / Occupants: 31|
|Aircraft damage:|| None|
|Location:||Eildon Weir, VIC -
|Phase:|| En route|
|Nature:||Passenger - Scheduled|
|Departure airport:||Albury Airport, NSW (ABX)|
|Destination airport:||Melbourne (unknown airport), VIC|
|Investigating agency: ||ATSB|
|Confidence Rating:|| Accident investigation report completed and information captured|
Shortly after the aircraft entered the holding pattern it suffered an aerodynamic stall and rolled approximately 126 degrees to the left and pitched nose down to approximately 35 degrees. The crew regained control after approximately 10 seconds. The aircraft lost 2,300 feet of altitude. The crew was not provided with a stall warning prior to the stall.
The investigation found that despite being certified to all required certification standards at the time, the Saab 340 aircraft can suffer from an aerodynamic stall whilst operating in icing conditions without the required warnings being provided to flight crew. This problem had been highlighted when the aircraft was introduced to operations in Canada and as a result a modified stall warning system was mandated for aircraft operated in Canada. This modification was not fitted to other Saab 340 aircraft worldwide.
1. The stall warning system did not activate prior to the stall.
2. The crew allowed the aircraft’s speed to slow below the published holding speed.
3. The crew interpreted the ice deposit as being less than that specified in the aircraft flight manual for activation of the wing de-ice system.
4. The crew misinterpreted the pre-stall buffet as propeller ice vibration.
5. The Saab 340 aircraft is capable of accreting ice deposits without visual clues being provided to the flight crew.
6. The aircraft was not fitted with the Canadian Stall warning system. If this had been fitted and activated, it would have (and activated) provided the crew with between 10 to 18 seconds warning of the impending stall.
ATSB Occurrence Nr. 199805068
| || |
|Investigating agency: ||ATSB |
|Report number: || |
|Status: ||Investigation completed|
|Download report: || Final report|
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