How turbulent is NRT-LAX typically?

Light to moderate. The strongest chop sits near the jet core, and crews plan cruise levels around it.

What is the best altitude to avoid turbulence on NRT-LAX?

Flying above the jet core, generally FL380-FL410, gives the smoothest ride. Below it the shear is stronger.

When is the best time of year to fly NRT-LAX?

Summer and early autumn, when the East Asian jet is at its weakest. Winter brings the strongest core winds.

What causes the turbulence on this route?

Shear at the boundary of the East Asian jet stream, the strongest sustained upper wind on the planet.

Turbulence forecast NRT → LAX. Tokyo Narita to Los Angeles. SkyBriefing.

Tokyo to Los Angeles: what the NRT to LAX corridor looks like

Departure: Tokyo Narita International Airport, Tokyo, Japan
Arrival: Los Angeles International Airport, Los Angeles, the United States
Great-circle distance: 8,754 km (4,727 nm)
Typical airborne time: 10h 41m
Usual cruise levels: FL340 to FL400
Initial track: northeast bound

Route overview

The NRT to LAX sector connects Tokyo Narita International Airport in Tokyo, Japan, with Los Angeles International Airport in Los Angeles, the United States. Measured along the great circle the two airports are 8,754 km apart, roughly 4,727 nautical miles, which is close to 10h 41m in the air before winds and routing are taken into account. The initial track is northeast bound, and the middle of the route sits in subtropical latitudes.

Leaving Tokyo

Tokyo Narita sits inland on the Boso peninsula plateau. Winter departures climb into the core region of the East Asian jet stream faster than almost anywhere else, because that jet sits over Japan through the cold season. The great-circle track leaves NRT northeast bound, and the first waypoint band of the flight sits close to 35.3N 165.7E. On a sector of 10h 41m, the climb to cruise takes roughly the first twenty to twenty five minutes.

The East Asian jet stream

Along the way the track passes over the open Atlantic and the open Pacific. The midpoint of the NRT to LAX track lies near 34.9N 11.0E, about 4,377 km from Tokyo, which is where the corridor spends its longest continuous stretch at cruise level. The East Asian jet stream dominates the winds along this track. Its core is narrow and its position moves day to day, which is why dispatchers replan the route each cycle. Clear air turbulence sits at the edges of that core, and the WAFS forecast shows where it is expected before the flight departs.

Cruise altitudes on this sector

Long haul crews normally start cruise around FL340, then step climb toward FL380 or FL400 as the aircraft burns off fuel and can hold a higher level. Choice of level matters because turbulence is layered: a change of two or three thousand feet often puts the aircraft into calmer air, and that is one of the first adjustments a crew will request.

Arriving into Los Angeles

Arrivals into LAX descend across desert and mountain terrain before reaching the coastal basin. The step from dry inland air into the marine layer is the usual explanation for the movement near the end of the descent. Descent normally begins around 34.4N 143.7W, roughly 2,189 km before LAX, and takes about half an hour from cruise level to touchdown.

Seasonal pattern

The East Asian jet stream peaks in winter and weakens through the summer, so late summer and early autumn sectors are usually the smoothest on this corridor.

Flying this route with less worry

It is worth remembering that turbulence of the kind found on the NRT to LAX track is uncomfortable and entirely within what the aircraft is built for. Wings are designed to flex, the flight is planned around the forecast, and the crew adjusts level or track when it helps. The live forecast above shows the current picture for this corridor so there are fewer surprises on the day.