When ADS-B is installed, a pilot must have it in transmit mode...

• A. At all times unless ATC requests otherwise
• B. Only in controlled airspace
• C. Only when required by regulation
• D. Never transmit if not asked

Answer: (A)

ADS-B Out is a surveillance tool that continuously broadcasts your position, altitude, and velocity to air traffic control and other receivers. Once it’s installed, you’re expected to keep it transmitting whenever you’re airborne in the airspace where ADS-B Out is required. The best answer reflects that ongoing obligation, with the understanding that ATC may ask you to turn it off for a specific reason or operation, but those requests are the exception, not the rule.

Reasons the other ideas don’t fit: transmitting only in controlled airspace or only when regulation requires would undermine the constant surveillance benefit ADS-B Out provides in most airspace. And never transmitting unless asked would defeat the purpose of having ADS-B Out, since the system is designed to provide continuous information to controllers.