What is clear-air turbulence?

The aircraft can bump a little even with a deep blue sky outside the window. That's called clear-air turbulence.

Causes

Clear-air turbulence mostly forms along the edges of jet streams and over mountain ranges, where layers of air moving at different speeds rub against each other. With no clouds, it can't be seen by eye or by weather radar.

How is it forecast?

• Weather centres calculate these areas from changes in wind speed and temperature and publish forecast maps.
• Aircraft report the bumps they meet, and the reports are shared with aircraft behind them.
• Pilots may change altitude based on this information.

What you feel

Mostly light, short jiggles. Pilots switch on the seatbelt sign and move to a calmer altitude if needed.

The seatbelt habit

Clear-air turbulence sometimes comes before the seatbelt sign. That's why keeping your belt loosely fastened while seated is the simplest and most useful habit.

SafeSkies shows the forecast along your route, so you know ahead which parts may be bumpy in clear air.