How Does Flight Planning Work?


An Air Canada captain answers your aviation questions. First up: how airlines find the best route to your destination.

An illustration of a blue map, half-folded, showing flightpaths and wind currents.

How does flight planning account for comfort, speed and efficiency?

Air Canada uses a software, Lufthansa Integrated Dispatch Operation, or Lido, that crunches the numbers. Routing, winds aloft, weather en route such as possible turbulence or thunderstorms, temperatures, restricted or closed airspace, fuel efficiency, weight and altitudes all enter the equation. Pilots receive the flight plan two to three hours before departure. On my Boeing 787 Dreamliner, the flight plan downloads into the navigation computers. With updated winds data and exact aircraft weight added, the airplane calculates precise fuel burns and altitudes to answer the most frequent question we pilots get: What’s our arrival time? Routes change on a daily and hourly basis. For example, a morning flight to Vancouver from Toronto might follow a Canadian route, but later in the day, it may be deemed more beneficial to fly over the northern U.S.

June 22, 2021
An illustration of an airline pilot standing in front of a window with planes flying in all directions on the other side.

What is the busiest airport you have flown into, and how does it compare to Pearson?

Passenger activity at the world’s busiest airports is measured in two ways: total passengers carried and total aircraft movements (takeoffs and landings). I have flown into most of them. Hartsfield–Jackson Atlanta International always takes first prize in passengers (110 million in 2019) but lost its number–one status for movements to Chicago O’Hare in 2019 (919,704). Toronto Pearson is in the big leagues as far as movements with 453,113 that year. Its runway layout sure helps to streamline flow.

An illustration of a sign depicting an airplane icon with four engines appearing to "fly" over a stylized blue sky with white clouds.

What happened to all the four–engine airliners?

All those highway signs depicting a four–engine jet for an international airport are behind the times: Concerns over fuel efficiency and the logistics of accommodating these oversize aircraft mean that the Boeing 747 (a.k.a. Queen of the Skies) and the goliath double–decker Airbus A380 are no longer built. Today, no four–engine passenger jets are flown by North American carriers, but you will see overseas airlines flying them – for now.

An illustration of a stopwatch, half the dial in shadow, with a white airplane icon on it.

What does it mean when your flight is labelled ETOPS?

Whenever a two–engine airliner flies 60 minutes or more away from the nearest airport (usually over water), a plan B alternate airport must be included in the flight plan. Extended–range Twin–engine Operations (ETOPS) have expanded beyond this limitation because of today’s jet engines’ high reliability. The extension can reach out to 180 minutes, and for my airplane, the Boeing 787 Dreamliner, it is certified up to 207 minutes (1,515 nautical miles).

An illustration of hands holding a tape measure and measuring a distance between two islands on a map.

Do you use the imperial or metric system?

Aviation relies on a hodgepodge of units for measurement. We use feet for altitude, except in China, North Korea and Mongolia (metres). Russia now uses feet at high altitudes but metres for low levels. Visibility is measured in feet and miles in North America, but metres and kilometres across the rest of the world. For speed, we use knots (nautical miles per hour) instead of statute miles per hour, but at higher altitudes speed is measured in relation to the speed of sound, or Mach number. Kilograms are used for weight in Canada, but in the United States it is pounds. Fuel is either in litres, imperial gallons or U.S. gallons. For an Air Canada pilot who travels overseas, navigating this measurement soup is part of the job description.

An illustration of a thermometer at a 45-degree angle with blue liquid at the bottom and an airplane icon at the top.

Do airplanes warm up in flight?

The high speeds we fly at will warm up any airliner’s surface. In fact, we have two temperature readouts in the cockpit: Static Air Temperature (SAT) reads the outside temperature, and Total Air Temperature (TAT) displays the sum of SAT plus temperature rise due to air compression and friction on the moving surface of the aircraft. The difference between SAT and TAT can be 40°C in flight. For example, flying in cloud at –10°C is conducive to airframe icing, but with a TAT of +10°C ice will not form. Fun fact: SAT is the “exterior temperature” displayed in the flight–maps feature on your seatback screen.

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Portrait of Air Canada's Captain Doug Morris
Photo: Reynard Li

Doug Morris is an author, meteorologist, instructor and Air Canada captain on the Boeing 787.