How is the required fuel for a flight calculated?

The correct calculation for required fuel accounts for both the duration of the flight and the fuel consumption rate, along with the necessary reserve fuel.

The required fuel is determined by first calculating the total time the aircraft will be in the air, which is then multiplied by the fuel flow (the amount of fuel consumed per hour). This gives you the total fuel needed for the flight based on the expected operational time. Additionally, reserve fuel is factored in, which is crucial for safety in case of unexpected situations such as extended holding patterns, diversions, or emergencies. Consequently, the formula combines the fuel needed for the planned flight and the reserve fuel to ensure that the aircraft carries an adequate supply for the entire journey, ensuring both safety and compliance with regulations.

The other choices do not comprehensively cover the necessary elements for accurately determining the required fuel. For example, simply multiplying the total time by reserve fuel does not take into account the actual fuel flow during the flight, rendering it inadequate. Likewise, adding fuel flow to reserve fuel does not consider the time aspect, which is critical for accurate calculations, while calculating required fuel based solely on total distance divided by fuel efficiency neglects the fundamental requirement of incorporating reserve fuel for safe operations.