In the event of an inadvertent departure from controlled flight, what is the first action to take?

The first action to take in the event of an inadvertent departure from controlled flight is to set the controls to neutral. This is crucial because neutralizing the controls helps to eliminate any excessive inputs that may have contributed to the departure. By allowing the aircraft to stabilize, it provides the pilot with the best opportunity to recover from the situation. Restoring control is paramount to preventing further loss of control, and ensuring the aircraft returns to a manageable attitude.

The other actions listed could be appropriate in different emergency situations but are not the immediate steps necessary for recovery from a loss of control. For example, turning off the Power Control Lever (PCL) or pulling the firewall shutoff handle may be relevant in engine failure or fire scenarios, but they are not directly beneficial in regaining control after an uncontrolled departure from flight. Checking altitude is important during flight but does not assist in recovering flight control in this specific situation.