Connection · one ticket · schedule Jun 6 – Jul 31, 2026 · records Aug 2025 – Jul 2026
Seattle → Boston via San Francisco: arrives on time 51%
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19:05 SEA → 21:21 SFOUA 2241 · United · 2h 16m · 22% on time, 2.7% cancelled
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1h 44m layover in San Francisco (SFO) · 45 min minimum on one ticket
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23:05 SFO → 08:01 BOS +1 dayUA 1665 · United · 5h 56m · 84% on time, 1.5% cancelled
Total trip 9h 56m, scheduled departure to arrival (Boston is 3 h ahead of Seattle). Times are local. Both flew on 37 of the last 56 days.
Makes the connection63%The first flight arrived more than 59 minutes late on 37% of the days it flew: too late for the 45-minute minimum connection on a 1h 44m layover.
Arrives on time51%First flight not cancelled (2.7% are) × connection made (63%) × second flight not cancelled (1.5% are) and within 15 minutes (84%).
Total trip9h 56mSEA 19:05 to BOS 08:01, layover included
Tight connection: often missed. The first flight is late enough to miss it on more than 1 day in 4.
Not yet counted: the second flight also leaving late (which helps), gate-to-gate distance at the hub, and rebooking after a missed connection.