San Francisco International Airport (SFO) is the premier international airport linking the US with the Asia-Pacific region, offering one of the most impressive long-haul networks of any US airport. With regular nonstop services to the likes of Delhi, Ho Chi Minh, Hong Kong and Singapore, SFO ranked as the US’ ninth-busiest airport, as per the latest OAG data, both overall and for international flights.

Its longest route has a block time of 17 hours and 40 minutes, which is among the longest scheduled commercial flights in the world today. In fact, looking at data from aviation analytics company Cirium, SFO has several city pairings clocking in at 15 hours or more, making it one of the world’s top airports for ultra-long flights.

SFO’s Ten Longest Flights At A Glance

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The longest nonstop flight out of SFO is its connection with Singapore Changi Airport (SIN), which is served by Star Alliance partners Singapore Airlines and United Airlines. With a distance of 7,340 nautical miles (13,593 km), the flight is blocked at 17 hours and 40 minutes, putting it narrowly ahead of Air India’s pairing with Delhi Indira Gandhi International Airport (DEL), which has a block time of 17 hours and 15 minutes. SFO-SIN gets a total of four daily flights — shared equally by Singapore Airlines and United — making it one of the most frequent ultra-long-haul routes from SFO alongside Hong Kong (HKG) and Manila (MNL).

Air India grabs the second and third spots with its services to Delhi and Kolkata’s Netaji Subhash Chandra Bose International Airport (CCU), using its Boeing 777-300ER fleet to serve both routes. United Airlines covers five of the above ten routes, including a brand-new connection with Australia’s Adelaide Airport (ADL), which the carrier launched in December 2025 with a three-times-weekly Boeing 787-9 service.

Nine of the ten longest routes at SFO utilize either the Airbus A350-900/1000, the Boeing 777-300ER, or the Boeing 787-9, with the sole exception being Emirates’ daily Airbus A380 flight to Dubai. Emirates is one of three airlines operating the A380 at San Francisco this winter season, along with British Airways and Lufthansa.

Honorable Mentions

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There are two other Air India routes that fall within the ultra-long-range category, but don’t make the top ten on account of making a stopover first. The two services are to Bengaluru (BLR) and Mumbai (BOM), but both involve a refueling stop in Vienna (VIE). The total flight time of these routes is between 18–19 hours, and both are served by AI’s Boeing 777-200LR fleet.

Other notable lengthy flights out of SFO include its pairing with Sydney (SYD) — this flight has a distance of 6,445 nautical miles (11,936 km) and is served by Qantas and United. According to Qantas, its flights to San Francisco typically take 14 hours and 40 minutes, while United’s flight has a scheduled block time of just over 15 hours.

A former route previously in the top ten was United’s service to Tel Aviv (TLV), which has since been indefinitely suspended. The carrier launched this pairing in 2016 with its Boeing 787 Dreamliner fleet, but scrapped service in 2023. Despite resuming flights to Israel from other US airports, it has yet to reinstate service from San Francisco.

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Future Ultra-Long-Haul Contenders

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SFO’s strategic location on the West Coast of the US has led to its strong connections across the Asia-Pacific market, so this is where future ultra-long routes are likely to materialize. Nonstop routes to key airports in India – such as Mumbai or Chennai – are likely candidates, and these connections are very feasible with Air India’s new widebody planes arriving in the next few years.

Other premier airports in Asia would also be viable nonstop destinations if the right aircraft are available. One that comes to mind is Bangkok (BKK), a city that United recently returned to after more than a decade away. While its service to BKK currently stops off in Hong Kong for refueling, a nonstop between SFO and BKK would be over the 15-hour mark.