Most long-haul airlines have some one-stop services, which could be for multiple reasons. United Airlines is no exception. It has had them for many years. In the remainder of 2026, the Star Alliance member’s longest offering will be timed at nearly 22 hours. Fancy that?

Most analysis on ‘longest’ flights usually focuses on nonstop services, especially those that are in ultra-long-haul territory. Perhaps for obvious reasons, there is less emphasis on one-stop operations. In this article, nonstop and one-stop flights are combined.

United’s Ten Longest Nonstop & One-Stop Flights

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For most airlines, one-stop services involve the same flight number and aircraft. They simply stop, refuel, and change crew. Passengers disembark and freight is unloaded, and—if the carrier has the required traffic rights—they load up for the next leg and continue.

Things are much more complicated for many of United’s one-stop flights. As four of the following ten markets show, United often uses the same flight number but deploys different aircraft on each leg.

Such operations involve changing planes in United’s Tokyo Narita hub, which has seen a significant revival recently. Despite having the same flight number but needing to change planes, they are nonetheless fifth freedom services, as they begin/end in the US. The arrangement is similar to previous operations by United and other US carriers operating to/from Japan for many years.

Given the highly unusual nature of them, some might not believe this is a like-for-like or fair comparison. As such, it might be better not to include them at all. To make it even more intriguing, the frequency on each leg is not necessarily always the same. Clearly, they are intriguing in themselves, not least because many of the destinations are new to United’s network.

The Longest ‘Proper’ One-Stop Operation

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Timed at up to 21h 40m, United began same-flight-number, same-plane, one-stop flights from Los Angeles to Bangkok, via Hong Kong, in October 2025. The Thai capital was previously part of the Star Alliance member’s network in 2009, when the 747-400 was flown via Narita.

United’s Ho Chi Minh City flights also operate via Hong Kong, just as they used to be. The airline returned to Vietnam in October 2025, having last flown there in 2016. As with Bangkok, Flightradar24 shows that the aircraft operating UA820 (to Bangkok) and UA152 (to Ho Chi Minh City) do indeed continue to the final Asian city.

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United’s Los Angeles-Hong Kong Loads Have Improved

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Until last October, United flew Los Angeles-Hong Kong on a so-called terminator basis. Flights primarily operated twice a day, but with relatively poor loads. According to the US Department of Transportation, the airline only filled 63.2% of seats between January and September.

The extension of flights to Bangkok/Ho Chi Minh City was partly to capture the considerable passenger volume to/from Los Angeles. After all, they are the US’s two most-trafficked long-haul markets without nonstop flights. Of course, the nature of the traffic—mainly diaspora and leisure travelers—and the vast distance means that yields are relatively low.

To help arrest the performance of United’s Los Angeles-Hong Kong route, extending flights to Bangkok/Ho Chi Minh City was a relatively cost-effective and low-risk endeavor. In November and December, seat load factors rose to 85.5% and 86.0%, respectively. United (and Cathay) will have more head-to-head competition between Los Angeles-Hong Kong in 2026, as Delta enters the market in June.