What must be considered when calculating the fuel and oil carried on board for a day VFR flight?

When calculating the fuel and oil needed for a day VFR flight, it is essential to consider foreseeable delays as well as an additional 20 minutes of fuel at cruising speed. This consideration helps ensure that the aircraft has sufficient fuel reserves to accommodate unexpected situations such as holding patterns, air traffic delays, or altitude adjustments during the flight.

Planning for these contingencies is a critical safety measure, as it gives the pilot a safety buffer in case conditions require extended flight times beyond the calculated travel distance. The practice of adding a reserve amount is aligned with aviation regulations and safety standards, which aim to minimize the risk of running out of fuel during flight.

Calculating fuel needs based solely on the distance to the destination without accounting for potential delays or holding times can lead to insufficient fuel reserves. Similarly, focusing exclusively on the manual's indicated fuel capacity does not account for real-time operational conditions that may impact fuel consumption. Therefore, taking into account both foreseeable delays and a buffer in fuel reserve ensures a more reliable and safer flight.