How Fast Is Jet Stream?

High-altitude jet streams blow at 80 m/s — 290 km/h sustained. Aircraft flying east gain enormous time savings; westbound flights lose as much. The phenomenon was first discovered by US pilots bombing Tokyo during WWII, who reported impossibly fast tailwinds.

The jet stream's path determines weather across continents — its meanderings cause many of the persistent weather patterns we experience as 'just bad luck'.

• Faster than helicopters cruise
• Discovered by US pilots over Tokyo, WWII