When does sterile flight deck begin on descent?

• A. Two single chimes, passing through 10,000 feet
• B. At the top of descent
• C. Upon landing
• D. After the taxi

Answer: (A)

Sterile flight deck means nonessential conversation is minimized to keep pilots focused during critical phases of flight. On descent, the moment you begin sterile procedures is when you pass through 10,000 feet, and you’ll hear two single chimes signaling that the sterile period has started. This boundary is chosen because workload and vigilance increase as you descend and prepare for approach, so restricting chatter helps pilots manage tasks and maintain situational awareness. Starting at the top of descent would be premature, while waiting until landing or taxi would miss the crucial approach phase and isn’t when the sterile period begins.