Narrative:The Saab was approaching Bathurst's runway 17 with gear down and flaps at 20 degrees. At a radio altitude of 1,266 feet above ground level and a speed of 133 knots the captain commanded the autopilot to roll the aircraft to the right to begin tracking downwind for runway 17. It attained 28 degrees right roll after 7 seconds. Approximately 1 second later, the aircraft commenced an uncommanded roll to the left at a recorded airspeed of 114 knots and a nose-up pitch of 8 degrees. The aircraft rapidly rolled to the left reaching 109 degrees left bank within 4 seconds, before pitching 27 degrees nose down 3 seconds later. During the recovery the aircraft rolled back through wings level to 56 degrees right wing low. The aircraft descended approximately 1,080 feet in 16 seconds, and the minimum radio altitude recorded was 114 feet/35m above ground level. The aircraft's aerodynamic stall warning systems of stick shaker, audible alarm, visual warnings and stick pusher, did not activate.
1. Although provided with visual cues (windshield wiper), the flight crew did not detect airframe or wing ice during the descent and therefore did not take measures to remove the ice.
2. The flight crew left the power setting unchanged at 17 per cent after levelling out when 50 per cent-60 per cent would have been appropriate given the aircraft configuration and environmental conditions.
3. The flight crew allowed the aircraft’s speed to slow below a safe speed.
4. The stall warning system did not activate prior to the stall.
5. The aircraft was not fitted with the Canadian stall warning system modification. If this had been fitted and activated, it would have alerted the flight crew and provided them with between 3-4 seconds warning of the impending stall.
6. The SOP did not require activation of the de-ice boots in known icing conditions as per the manufacturer documentation.
7. The SOP allowed for the use of the autopilot during icing conditions which masked tactile cues regarding the increasing nose up attitude.
Official accident investigation report
|investigating agency: ||Australian Transport Safety Bureau (ATSB) - Australia |
|report status: ||Final|
|report number: ||ATSB report BO/200203074|
|duration of investigation:||579 days (1 year 7.1 months)|
|download report: ||
Inflight Loss of Control due to Airframe Icing
(ATSB report BO/200203074)
Follow-up / safety actions
The investigation identified a number of other occurrences involving Saab 340 aircraft stalling where little to no stall warning had been provided to flight crew while operating in icing conditions. This included a Saab operated by an Australian operator, which resulted in a number of ATSB recommendations being issued in that investigation, not all of which were accepted and acted upon. Some of those recommendations have been re-issued.
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not
display the exact flight path.
Distance from Sydney-Kingsford Smith International Airport, NSW to Bathurst-Raglan Airport, NSW as the crow flies is 153 km (95 miles).