Jet Stream and Flight Times

The jet stream is a fast, narrow river of air high in the atmosphere, flowing mainly west to east. Eastbound flights ride its tailwind and arrive sooner; westbound flights fight a headwind and take longer.

What it is

Jet streams occur near the top of the troposphere, around airliner cruise altitudes, with winds that can exceed 200 km/h. They shift with the seasons, and are strongest in winter.

Effect on flight time

A tailwind raises ground speed. A flight from Europe to Pakistan flies mostly east and often gains time; the return flight faces headwinds and takes longer. The difference can be an hour or more on long flights. Flights to North America from Pakistan, which are westbound, are often longer than the reverse.

Planning routes

Airlines plan routes that balance distance and wind, so the track is not always the shortest. See why planes fly curved routes.

On a tracker

Ground speed varies with the wind. See ground speed and how to read altitude, speed and vertical rate. A tailwind can push ground speed well above the aircraft’s speed through the air.

Turbulence

Clear-air turbulence can occur near the edges of the jet stream; see thunderstorms and turbulence.

General information only, not legal or safety advice. Details change; check with your airline and the relevant authority. See our editorial policy.