For a reciprocating-engine-powered air carrier airplane, how much fuel reserve is required upon arrival at the most distant alternate airport?

The correct answer emphasizes that a reciprocating-engine-powered air carrier airplane must retain a fuel reserve upon arrival at the most distant alternate airport sufficient for 45 minutes of flight at normal cruising fuel consumption. This requirement is established to ensure that in the event of unexpected conditions—such as needing to divert to an alternate airport—there is enough fuel onboard to safely complete the flight without the risk of fuel exhaustion.

This 45-minute fuel reserve standard provides a buffer for a range of potential circumstances, including adverse weather or air traffic control delays, that could necessitate extended flight time. It is critical for maintaining safety and ensures that pilots and dispatchers are prepared for contingencies that could affect the aircraft's ability to land at the intended destination.

Other options, while they may address certain operational considerations, do not meet the regulatory requirement specific to alternate airport fuel reserves. The requirement is specifically set at 45 minutes to optimize safety margins and operational reliability.