What is the jet stream?

The same thing can be behind a flight arriving early and light bumps in clear skies: the jet stream.

What is it?

Jet streams are fast, narrow bands of wind circling the globe from west to east near cruising altitude. Their speed can top 200 km/h, and they're stronger in winter.

Effect on flight time

An aircraft with the jet stream behind it speeds up over the ground; one flying into it slows down. Airlines plan routes every day around these winds. It's one reason eastbound flights are often shorter.

Link to turbulence

Along the edges of the jet stream, layers of air move at different speeds, so there can be light bumps even without clouds. This is called clear-air turbulence. Weather centres forecast these areas, and pilots share information and change altitude if needed.

Seeing it ahead

SafeSkies' turbulence forecast also shows these light-bump areas caused by the jet stream along your route. Knowing the reason for a “clear sky but bumpy” moment ahead of time makes it easier.