ATS Flight Plans and Fuel Requirements
Core concepts
An ATS flight plan (ICAO format) contains aircraft identification, flight rules, type of flight, aircraft type and wake category, equipment, departure and destination aerodromes, route, level, EET, alternate aerodromes, and fuel endurance. It must be filed at least 60 minutes before departure for IFR flights (or as specified by the state). Fuel requirements for commercial operations include taxi, trip, contingency, alternate, final reserve, and additional fuel.
Traps
Questions test: the difference between the ATS flight plan and the operational flight plan; the required fuel endurance figure; the correct item numbers in the ICAO format; and the requirement to notify ATS of changes (e.g., revised ETA, diversion). Also watch for the difference between 'fuel endurance' (total fuel in hours and minutes) and 'fuel on board'.
Worked example / rule of thumb
Rule: fuel endurance = total usable fuel ÷ average fuel flow. Example: 400 kg usable fuel, average flow 50 kg/h → endurance 8 h. If the planned flight is 2.5 h, the endurance figure in the ATS flight plan is 8 h, not 2.5 h. Always file the ATS flight plan with the correct endurance and alternate aerodromes.