UA3921 San FranciscoSFO · 15:00 DenverDEN · 21:20
UA3921 by United Airlines flies from San Francisco (SFO) to Denver (DEN).
Same number through SFO → ORD → DEN
scheduled from SFO
The route today
live boardsWeather lens
Delay & cancellation outlook for this flight
Measured, 90-day sampleConditions at SFO and DEN are near their clear-air norm right now, so this reflects the route's recent baseline rather than a weather penalty. For this route and airline, under conditions like today's, over the last 90 days.
Pro Flight Search tracking, 90 days · the weather × delay correlation study → · live weather risk by airport →
When it flies
scheduled departuresEach mark is a scheduled departure at its origin-local time. Today is highlighted.
Other San Francisco to Denver flights today
same route · United AirlinesIf UA3921 is cancelled, these are the other United Airlines nonstop flights from San Francisco to Denver on the same day, with scheduled departure times in SFO local time. Most flights posting a delay still operate — rebooking usually only beats a very large posted delay. Every airline on this route →
How UA3921 actually runs
Pro Flight Search has tracked every published board update for UA3921 across the SFO and DEN boards: schedule changes, gate pushes and actual clocks. Early read — pattern not clear yet. Only 2 completed legs so far: landed +188 min. Not enough to call it.
The verdict above is that record speaking, so it reflects how UA3921 operates rather than what the timetable promises. Numbers refresh as new flights operate.
Planning around UA3921? Will a delayed flight be cancelled? · Do planes make up time in the air? · How we measure
Journalists, bloggers, and researchers may cite this page with attribution and a link to Pro Flight Search.
Pro Flight Search — UA3921 San Francisco to Denver on-time performance, measured from the SFO and DEN airport boards.
https://proflightsearch.com/flight/UA3921
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