Río Negro

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.

The accident was caused by the collision of the aircraft with the ground during the final approach to Bariloche runway after an improper and premature descent which was below safety limits. The accident can be attributed to a procedural error by the crew during the final approach in that they abandoned the ILS procedure, an action strongly and unduly influenced by the interruption of the VOR signal and also probably by the state of mind of the pilot-in-command.

Controlled flight into terrain.

It is believed that the accident was the consequence of a controlled flight into terrain after the crew initiated the descent prematurely when he did not have sufficient ground assistance. It is possible that the crew was unaware of the strength of the wind in the area when the accident occurred, winds that caused the aircraft to divert from the prescribed approach path.