Final answer:
The required minimum fuel for a flight with two alternates listed on the release is determined by aviation regulations and typically covers reaching the destination, alternate airport, and an additional 45 minutes of flight at normal cruising speed, along with any required safety margins.
Step-by-step explanation:
The required minimum fuel for a flight with two alternates listed on the release for domestic operations depends on the specific regulations of the aviation authority governing the flight, such as the Federal Aviation Administration (FAA) for the United States. However, a general rule of thumb is that the aircraft must have enough fuel to reach the first airport of intended landing, fly to the alternate airport, and then fly for an additional 45 minutes at normal cruising speed. Furthermore, certain safety margins are also included like contingency fuel which is typically around 5% of the planned fuel burn (but may differ based on the regulatory authority), and additional reserves that may be required by company policy or particular circumstances of the flight.
For instance, under FAA rules as specified in FAR (Federal Aviation Regulations) Part 91.167, airplanes flying IFR with two alternates must have enough fuel to reach the intended first airport, then to the alternate, and then fly for 45 minutes at normal cruising speed or reach the second alternate (whichever requires less fuel). Additionally, under IFR conditions, the listed 'alternate airport' should have the forecasted weather at arrival that meets specific criteria, otherwise additional fuel and considerations are necessary.