What is the primary fuel requirement for IFR flights?

The primary fuel requirement for IFR (Instrument Flight Rules) flights is designed to ensure that aircraft have sufficient fuel to safely complete their journey, even in the event of unforeseen circumstances. The correct answer emphasizes the need for enough fuel not only to reach the intended destination but also to have a buffer in case diversions are necessary due to weather or other factors. This buffer is defined as enough fuel to fly to the alternate airport and includes an additional 45 minutes of fuel at normal cruising speed, ensuring a substantial safety margin.

This approach is in line with regulations set by aviation authorities, which mandate that flights should always plan for contingencies. The specifics of the fuel requirements ensure that flights can safely handle potential delays or changes during the flight, which is critical when operating under IFR conditions where weather and air traffic can be unpredictable.