Ask the pilot: How do you calculate flight time?

How fast can a plane actually fly? Does it always take the most straightforward route? When do the aircraft get a rest? And what does it take to actually fly one? The people with the answers are the SAS pilots.

How do you calculate flight time?


Jimisola Laursen       

Age: 41
Career: Joined SAS in 2014. Has flown CRJ900s and 737NGs. Started flying the ­Airbus A320 in 2016. A former track athlete and 400m indoor Nordic record holder.
Home base: CPH
Flies: Airbus 319/320/321
Flight hours: 5,400

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Hi Peter,
Just as with other modes 

of transport, travel time is worked out by calculating distance divided by speed. In this case, the flight duration is the distance of the flight route divided by the ground speed.

A flight from A to B can be carried out over one or several routes. These routes are like roads in the air with the addition that you can also fly at different heights and that wind speed can vary between them. Ideally, you choose the most optimal flight route based on the shortest possible duration, as this saves fuel. However, many other factors such as weather, slot times, military traffic, other air traffic and so on can affect the choice of route.

The distance of the flight is actually quite simple to work out and it’s easy to do manual calculations on a map using a ruler, but at SAS, we use computer programs.

It does, however, get a bit more complicated when you want to calculate the speed over the ground (GS, or Ground Speed) which is the aircraft’s speed in relation to the air (TAS, or True Airspeed) taking into account wind speed (headwind and tailwind affect the speed over the ground). The shorter the interval you use to calculate the speed over the ground, the more accurate the flight time will ultimately be.

Jimisola Laursen
First Officer

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