When does sterile flight deck begin?

• A. Once the flight deck door is closed and the cabin is reported secure for taxi.
• B. Before engine start
• C. After takeoff
• D. Upon landing

Answer: (A)

Sterile flight deck is the period when only essential cockpit communication and actions are allowed to maximize safety during critical phases of flight. It begins when the flight deck door is closed and the cabin is reported secure for taxi. At that moment the cabin is no longer a source of routine disturbance, and the crew can focus fully on taxi, engine start preparation, and the ensuing takeoff. Starting earlier—before the door is closed or before the cabin is secured—could allow nonessential activity or interruptions to intrude, reducing the pilots’ situational awareness during a vulnerable phase.