Reverse Flow arrival into San Francisco (KSFO).

San Francisco International Airport (KSFO) operated in its less common "east flow" or reverse flow configuration when United Airlines Flight 1593, arriving from Newark Liberty International (KEWR), was photographed on short final for runway 10L. Under normal conditions, KSFO's dominant traffic pattern routes arrivals onto the 28-side runways — 28L and 28R — taking advantage of the region's prevailing westerly and northwesterly winds off the Pacific. When surface winds shift to the southeast, as was the case during this observation, air traffic control transitions the field to an east flow configuration, directing arrivals onto runways 10L and 10R, which point toward the San Francisco Bay rather than toward the ocean.

Reverse flow operations at KSFO represent a meaningful operational shift for both controllers and flight crews. In the standard west flow, arriving aircraft track over the Pacific or the coastal communities west and south of the airport before touching down heading west. In east flow, arrival paths shift dramatically — aircraft approach from over the East Bay, flying over Oakland and surrounding urban areas before crossing the bay shoreline on short final. NorCal TRACON must reconfigure the entire terminal area arrival and departure structure, including STARs, departure procedures, and sequencing logic, all of which can temporarily reduce throughput as the transition is coordinated. Flight crews must be prepared for different approach briefings, altered noise abatement constraints, and different visual or instrument approach procedures than those they commonly use at this destination.

For line pilots who regularly operate into KSFO, familiarity with the reverse flow configuration is operationally essential, though the infrequency of east flow — occurring perhaps five to fifteen percent of operating days depending on seasonal weather patterns — means some crews encounter it rarely. Transcontinental crews inbound from the East Coast, like those operating the EWR–SFO pairing, are particularly susceptible to encountering it after a five-plus-hour flight during which conditions may have changed significantly since departure. The ILS and RNAV approaches to runways 10L and 10R have different terrain and obstacle environments than those to the 28s, and the visual picture on short final differs substantially, with the bay and the East Bay hills behind the aircraft rather than ahead.

The observation reflects a broader pattern of weather-driven operational variability at major West Coast hubs. KSFO, like Los Angeles International (KLAX) and Seattle-Tacoma (KSEA), experiences periodic wind-driven configuration changes that cascade through regional airspace. At KSFO specifically, the marine layer, thermal gradients driven by the Central Valley, and seasonal pressure patterns can push winds to easterly or southeasterly headings, particularly in shoulder seasons. For corporate and charter operators planning SFO arrivals, east flow conditions can produce ground delays, rerouting, and altered fuel planning requirements, making real-time weather awareness and dispatcher coordination critical during periods of unsettled Bay Area meteorology.