Accident Saab 340A LV-CEJ,

ASN Wikibase Occurrence # 321116

Date:	Wednesday 18 May 2011
Time:	20:48
Type:	Saab 340A
Owner/operator:	SOL Líneas Aéreas
Registration:	LV-CEJ
MSN:	340A-025
Year of manufacture:	1985
Total airframe hrs:	41422 hours
Cycles:	44477 flights
Engine model:	General Electric CT7-5A2
Fatalities:	Fatalities: 22 / Occupants: 22
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	20 km N of Prahuaniyeu, RN - Argentina
Phase:	En route
Nature:	Passenger - Scheduled
Departure airport:	Neuquén Airport, NE (NQN/SAZN)
Destination airport:	Comodoro Rivadavia Airport, CB (CRD/SAVC)
Investigating agency:	JIAAC
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
A Saab 340A passenger plane, registered LV-CEJ, was destroyed when it crashed 20 km north of Prahuaniyeu, Argentina. The 19 passengers and three crew members on board did not survive the accident.
The airplane operated on SOL Líneas Aéreas flight 5428 from Córdoba (COR) to Mendoza (MDZ), Neuquén (NQN) and Comodoro Rivadavia (CRD). The flight departed Neuquén at 20:05 for the final leg of the flight. The aircraft climbed to FL190. After flying for 24 minutes, the pilot levelled the aircraft at 17800 ft, and remained at this level for approximately 9 minutes.
When flying at FL179, the aircraft began to pick up ice. The copilot radioed air traffic control for permission to descent. The flight was then cleared down to FL140. However, while descending the crew members commented on the growing ice accretion on the wind shield and wings. By the time the aircraft had reached FL140, the icing conditions were severe. The aircraft flew for approximately two minutes with a straight and level flight attitude, increasing the accumulation of ice.
The airspeed dropped until the airplane stalled. The pilots attempted to regain control of the plane, but failed. The airplane impacted terrain and burned.

Cause:
During a commercial, domestic passenger flight, while cruising, the crew lost control of the aircraft, which uncontrollably impacted the ground due to severe ice formation caused by the following factors:
> Entering an area with icing conditions without adequately monitoring the warning signals from the external environment (temperature, cloudiness, precipitation and ice accumulation) or the internal (speed, angle of attack), which allowed for prolonged operations in icing conditions to take place.
> Receiving a forecast for slight icing - given that the aircraft encountered sever icing conditions - which led to a lack of understanding regarding the specific meteorological danger.
> Inadequately evaluating the risks, which led to mitigating measures such as adequate briefing (distribution of tasks in the cockpit, review of the de-icing systems, limitations, use of power, use of autopilot, diversion strategy etc.) not being adopted.
> Levels of stress increasing, due to operations not having the expected effects, which led the crew to lose focus on other issues.
> Icing conditions that surpassed the aircraft's ice protection systems, which were certified for the aircraft (FAR 25 Appendix C).
> Inadequate use of speed, by maintaining the speed close to stall speed during flight in icing conditions.
> Inadequate use of the autopilot, by not selecting the IAS mode when flying in icing conditions.
> Partially carrying out the procedures established in the Flight Manual and the Operations Manual, when entering into areas with severe icing conditions.
> Realizing late that the aircraft had started to stall, because the buffeting that foretells a stall was confused with the vibrations that signify ice contamination on the propellers.
> Activation of the Stick Shaker and Stall Warning at a lower speed than expected in icing conditions.
> Using a stall recovery technique which prioritized the reduction of the angle of attack at the expense of altitude loss, and which was inappropriate for the flight conditions.
> The aileron flight controls reacting in an unusual manner when the aircraft lost control, probably due to the accumulation of ice in the surfaces of these, which made it impossible for the aircraft to recover.
> The increasingly stressful situation of the crew, which affected its operational decision-making

Accident investigation: