San Francisco to Seoul: what the SFO to ICN corridor looks like
- Departure
- San Francisco International Airport, San Francisco, the United States
- Arrival
- Incheon International Airport, Seoul, South Korea
- Great-circle distance
- 9,086 km (4,906 nm)
- Typical airborne time
- 11h 04m
- Usual cruise levels
- FL320 to FL410
- Initial track
- northwest bound
Route overview
San Francisco International Airport (SFO) in San Francisco, the United States, to Incheon International Airport (ICN) in Seoul, South Korea, is a great-circle distance of 9,086 km, about 4,906 nautical miles. At typical jet cruise speeds, and with an allowance for climb, descent and approach, that works out to roughly 11h 04m of airborne time. The great-circle track leaves San Francisco northwest bound and spends most of the flight in subtropical air.
The East Asian jet stream
Along the way the track passes over the open Atlantic and the open Pacific. This corridor lies under one of the strongest sustained upper winds on the planet, the East Asian jet stream. Eastbound flights ride it and arrive earlier, westbound flights are routed around the core to avoid the headwind. The turbulence here is clear air turbulence generated at the jet boundary, and it is a well mapped, well forecast feature of the region.
Cruise altitudes on this sector
Ultra long sectors begin cruise lower, often near FL320 because of the fuel load, and finish two or three step climbs higher, up to FL400 or FL410. 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.
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
Turbulence on this corridor is a comfort issue rather than a safety one. Airliners are certified to handle loads well beyond anything the atmosphere produces here, crews are trained for it, and the seat belt sign is the tool that keeps the cabin settled. What this page adds is knowing in advance: the map and Calmness Score above use current WAFS forecast data for SFO to ICN, so you can see what to expect before you board.