Neuquén-Juan Domingo Perón

The loss of control during taxiing was the consequence of the combination of the following factors:
- The electric pump which controls fluid pressure in the hydraulic system was not operational, generating a deficit of fluid pressure in the hydraulic system.
- The low fluid pressure warning in the hydraulic system was not recognized by the crew.
- The crew could not control the path of the aircraft due to the unavailability of nose wheel steering.
- The persistence of an informal practice among the crews of the operator on the operation of the hydraulic system, contrary to the concept of operation of the hydraulic system established by the manufacturer.
- The lack of detection of the informal practice on the operation of the hydraulic system by the operator's safety monitoring mechanisms.

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 exact cause of the accident remains unclear. The crew did not send any distress call prior to the loss of control. It is believed that the accident was the consequence of a possible in-flight fire or toxic fumes emanating in the cabin due the presence of polyethylene stored in several boxes that were not properly packed according to dangerous goods transportation procedures.

The brakes and reverse thrust systems were unserviceable following a failure of the primary hydraulic system. The auxiliary braking system was also unserviceable. For unknown reasons, the problem has not been identified by the flying crew neither the maintenance personnel.