Avgeek Alert: What Is a Flight Plan?


When film directors shoot their movies, they make sure that everything is perfect: for example, actors are all in place; their lines are memorised; there’s a timeline with expected completion date. In short, any detail that ensures that the project will be completed successfully. Well, this is what a aircraft’s flight plan is: the detailed planning of any variable that could influence a perfect flight. What must (and usually does) a good flight plan include?

Both the International Civil Aviation Organisation (ICAO) and national aviation authorities such as Spain‘s AENA specify that a flight plan must be filed under the different conditions detailed by each organisation. But in essence, filing one is a prerequisite for the vast majority of flights. This is not only because it’s part of national and international aviation protocols, but for practical reasons. The crew, by noting every technical aspect, monitors every detail of the flight, which significantly increases safety. In addition, flight plans are an excellent tool for air traffic management. Following are its main components:


Selecting the Flight Segments

Before selecting which route to fly, pilots obviously need to know something about the geography of the areas they will fly over. For example, whether there is a large river, a mountain range, or one or more a big cities. They’ll do all this on a physical map, and without selecting the segments yet will look for all those visual references that will help them plan the flight.

The route itself comes next. Pilots will take into account the type of airspace; the topography (valleys, mountains, rivers, etc.) they’ll be overflying; the weather forecast for the duration of the flight, etc. Then they’ll choose their route keeping in mind the various constraints that may arise with these variables. They must also decide their flight altitude to fly as well as altitude limits for landing and take-off (although these are usually designated by the airports themselves). The plan is, so to speak, a technical script that will help the pilot learn the specific characteristics of the flight on that day and time.

Identifying Alternative Airports

Once they have the general picture of the flight in optimal conditions, pilots incorporate alternative airports into the plan – where they will land in case something unexpected comes up during the journey. Such alternative airports must of course be near the flight’s starting or end point, or along the route. Each alternate airport is chosen according to different variables, such as the distance from the original route and its characteristics (airport, visual circuit, altitude, special procedures, etc.), and all of this is duly recorded.

Crafting the Flight Plan

Each section of the flight plan has a heading with the main details and, underneath, a short coded narrative providing visual references (pilots aren’t required to to memorise each of these references, but they must know how to identify them afterwards, which occurs because of this revision method).

Critical elements are fuel, weight, and balance The fuel must be calculated, not just by counting the kilometres to be travelled but also multiple factors such as ascent and descent phases, possible diversions to alternative airports, and so on – all determined via pretty much standardised formulas. And to know how much fuel can be carried, the weight and balance of the aircraft are essential data, and pilots must determine how many kilograms of cargo the aircraft is carrying and whether the centre of gravity is within the established standards.

Determining Weather Conditions

As we mentioned above, weather is another one of the most important factors in making a flight plan, and it’s observed not just during the planning phase, but also just before the flight itself. Pilots report weather phenomena that may affect the estimated departure and arrival times, such as heavy rain or wind, as well as the meteorological conditions at both the origin and destination airports. This information is of course essential, as it can delay or cancel a flight.

Confirming Airport Characteristics

Pilots need to familiarise themselves with key details of the procedures are at the origin and destination airports for the flight plan, from the name of the airport to the orientation of the runways; the length of the runways; control tower data; approach frequencies; and much more.

Taking Additional Data into Account

These include:

– Knowing the most important radio frequencies, both during cruise and at the airports.
– The performance planning of the trip (pressure, altitudes, etc.).
– A fresh weather check prior to take-off.

Obviously, most of this is done today with very powerful software systems, but there was a time when computers did not exist and the calculation of each of these very large amounts of data had to be done by hand!


Photo | Oselote