DL3991 San FranciscoSFO · 20:58 SeattleSEA · 23:13
DL3991 by Delta Air Lines flies from San Francisco (SFO) to Seattle (SEA) for the Tue, Oct 13 departure.
departs SFO · on schedule
board checked 37m ago · checking again in 45s
The route today
live boardsWeather lens
Delay & cancellation outlook for this flight
Measured, 90-day sampleConditions at SFO and SEA 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 Seattle flights today
same route · Delta Air LinesIf DL3991 is cancelled, these are the other Delta Air Lines nonstop flights from San Francisco to Seattle 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 DL3991 actually runs
Pro Flight Search has tracked every published board update for DL3991 across the SFO and SEA boards: schedule changes, gate pushes and actual clocks. Early read — pattern not clear yet. Only 2 completed legs so far: departed +11 min. Not enough to call it.
The verdict above is that record speaking, so it reflects how DL3991 operates rather than what the timetable promises. Numbers refresh as new flights operate.
How this operation is measured
Board log
scheduled → actual, per operationAircraft
Recent tails: N320SY.
Board clocks recorded as SFO and SEA published them.
Planning around DL3991? Will a delayed flight be cancelled? · Do planes make up time in the air? · How we measure
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Pro Flight Search — DL3991 San Francisco to Seattle on-time performance, measured from the SFO and SEA airport boards.
https://proflightsearch.com/flight/DL3991