Los Angeles to Tokyo: what really shapes the LAX-NRT corridor
- Departure
- Los Angeles International Airport, Los Angeles, the United States
- Arrival
- Tokyo Narita International Airport, Tokyo, Japan
- Great-circle distance
- 8,754 km (4,727 nm)
- Typical airborne time
- 10h 41m
- Usual cruise levels
- FL340 to FL400
- Initial track
- northwest bound
Route overview
The Los Angeles to Tokyo Narita route is flown daily by Japan Airlines, ANA, Delta, United, American, and Singapore Airlines using aircraft like the 787-9, 777-300ER, and A350. Westbound the trip takes roughly 11 hours against the prevailing winds, while eastbound is closer to 10 hours with the jet stream at your back. The great circle track carries you north along the coast of California, out over the Gulf of Alaska, past the Aleutian Islands, and down toward Japan at cruise altitudes between FL320 and FL400.
Why turbulence happens on this route
The dominant weather feature on this corridor is the Pacific jet stream, which in winter is the strongest sustained upper-level wind found anywhere on earth. Core speeds routinely exceed 180 knots and occasionally top 220 knots off the coast of Japan. Where that fast river of air meets slower surrounding air, you get sharp wind shear, and where you have wind shear you can get clear-air turbulence. The Aleutian arc adds a second factor. Storm systems sweep across the northern Pacific and mix cold polar air with warmer subtropical air, creating steep temperature gradients along our track. On the eastbound leg, crews often ride inside the jet for a huge speed boost, deliberately picking altitudes where the ride is smoothest. On the westbound leg, we usually route further south to avoid the strongest headwinds, which also tends to give a calmer ride.
Which seasons are bumpiest
December through March is peak Pacific jet season, and this is when clear-air turbulence over the northern Pacific is most likely. Even so, most of these winter flights are smooth for the majority of the ride, with rough patches concentrated in one or two zones our forecasters can predict. May through September is much calmer as the jet weakens and drifts north. Late summer typhoon activity near Japan is a separate concern for the arrival phase, but our dispatchers and controllers route flights well clear of any tropical systems long before you reach Japanese airspace.
How pilots handle it
Preflight for LAX to NRT includes detailed wind and shear charts across the whole Pacific. Our crew picks an initial cruise altitude that sits above or below the sharpest wind gradient, and we plan step climbs as fuel burns off. In flight we exchange pilot reports with other aircraft ahead of and behind us on the same tracks, so if a 777 an hour ahead reports smooth air at FL380 we can request the same. We in the cockpit also watch temperature deviations from standard: a sudden warm or cold pocket often precedes a bumpy patch, and that gives us a few seconds to switch on the seatbelt sign and warn the cabin.
What you can do as a passenger
Keep your seatbelt fastened whenever you are seated, since clear-air turbulence on the Pacific can arrive without warning. Choose a seat over the wing if you can, as it moves less than the tail or nose. Drink water regularly and go easy on caffeine and alcohol, both of which can heighten anxiety. If you feel a bumpy patch starting, close your eyes and try a slow breathing pattern: in for four seconds, out for six, repeated for a minute or two. This physically calms your nervous system and helps the sensation pass more comfortably.