Flight Plan Preparation and ATS Filing
What the flight plan is for
An ATS flight plan exists so that search and rescue, air traffic services and adjacent units know who you are, where you intend to go and when. It is a legal declaration of intent, so accuracy matters more than speed. Understand the difference between filing, activating and closing, and know who is responsible for each. In controlled airspace the plan is usually activated by the ATS unit; outside it, you may need to activate by radio or by relay.
Structure
Be comfortable with the standard fields: aircraft identification, flight rules and type of flight, type of aircraft and wake category, equipment, departure aerodrome and time, cruising speed and level, route, destination, total elapsed time, alternates, fuel endurance and persons on board. Know the conventions for route description, including designated routes, significant points, change of speed or level, and the meaning of DCT. Understand the difference between a full plan and an abbreviated plan for repetitive flights.
Traps
Examiners like the endurance field: it is fuel endurance in hours and minutes, not total flight time, and it must exceed the total elapsed time. Another trap is departure time, which is the off-blocks or take-off time as specified by the rules you operate under, not your estimate. Watch for questions on when a plan must be filed before departure and how much deviation from the filed route or level requires an amendment.
Worked example
A flight departs at 0915, takes 2 h 40 min, and carries fuel for 4 h 05 min. Total elapsed time is E0240; endurance is E0405. If the flight is delayed 40 minutes, the elapsed time is unchanged but the destination ETA and any subsequent ATS coordination must be updated, and some states require a delay message.