ADS-B Out equipment is mandatory for aircraft operations in which types of airspace?

The correct answer indicates that ADS-B Out equipment is mandatory for aircraft operations in Class A, B, and C airspace. This regulation is part of the FAA's efforts to enhance situational awareness and safety in the National Airspace System.

Class A airspace, which extends from 18,000 feet MSL up to and including FL600, is primarily used by high-altitude commercial aircraft, and effective monitoring and communication are critical at these altitudes. Class B airspace surrounds the busiest airports and requires strict adherence to control procedures, where the presence of ADS-B Out helps air traffic controllers maintain an efficient flow of traffic. Class C airspace, typically around airports with a significant level of air traffic, benefits from ADS-B Out technology as it provides information to air traffic control that enhances both safety and operational effectiveness.

While ADS-B Out is not mandated in Class D airspace, which is typically smaller and less congested than the other classes, the use of ADS-B can still provide benefits. The requirements for ADS-B Out in Classes A, B, and C help improve the overall safety margin and efficiency of the airspace system.