Jet engine

Ask the pilot: How do you start a Jet Engine?

The pilot answers the question we all wonder about.

Photo: Andy Prhat
September 2022
Even the most experienced travelers have many questions about the inner workings of airplanes. How do they react to weather conditions? What do all the noises mean? How do they take off and land? The experts with all the answers are, of course, the pilots.

“We get our power from a small engine.”

How do you start a jet engine?


Hi Jeff,

To start an airplane is slightly different than how you start your car. First, we don’t really have a key. When we arrive at the aircraft we use electricity from the ground to start up all our systems without starting the engines.

When we are finally ready to start our engines and push back from the gate, we get our power from a small engine and generator located in the tail of the aircraft. This engine also gives us the power we need to start the engines. When you turn your key in a car, a small electrical engine helps start the engine by rotating it. In some cases, the same can be done on jet engines, but on most, and on all SAS aircraft, we actually use high-pressure air to get the engine turning.

When we turn the starter switch in the cockpit, air is directed from the small engine in the tail to the selected engine we want to start first. This high-pressure air gets the engine to turn and build up internal pressure in the combustion chambers. When the engine is rotating sufficiently, fuel is sent to the engine, and the fuel is ignited, thereby further building up more pressure to rotate the engine. Finally, the engine reaches a speed where it is self-sustained, and air from the starter engine is removed. The engine is now running on its own at idle speed, and we’re ready to start the next engine.

Pernilla Nilsson
Senior First Officer

Pernilla Nilsson

Title: Senior First Officer
Home base: Copenhagen
Flies: A319, A320, A321
Flight hours: 13,500
Favorite airport: Most of the Norwegian airports. They can be very challenging in harsh weather but a beautiful day it’s unbeatable. The landscape is fantastic with the mountains and fjords. You’ll never get tired of this view.