In the event of unexpected turbulence, what is the first action the Flight Deck should take?

In the event of unexpected turbulence, the first action the Flight Deck should take is to ensure that the seatbelt sign is on. This is crucial for the safety of all passengers and crew onboard, as it alerts them to take their seats and fasten their seatbelts, minimizing the risk of injury during turbulent conditions. By activating the seatbelt sign, the crew can help prevent passengers from moving about the cabin, which could lead to accidents or injuries from sudden jolts or movements of the aircraft.

While making an announcement to passengers or contacting ground control may be important afterward, the immediate priority is to ensure that passengers are secured. Turning off the seatbelt sign would effectively counteract this safety measure, and contacting ground control is typically not the first action taken in response to in-flight turbulence.