DL3991 SEA → SFO

Delta Air Lines · Seattle, WA to San Francisco, CA · 292 flights observed, 2025-07-01 to 2026-06-30 · 679 mi

This flight has been getting less reliable recently — 2026-06's on-time rate (40%) is well below the 77% average from earlier months.

DL3991 covers more than one route in the data window — the stats below are for SEA → SFO, the one it has flown most recently. The others are linked under “Other routes”.

On-time arrival
72%
Median delay
0 min
90th percentile
+53 min
Cancellation rate
1%

How often is DL3991 on time?

Across 292 flights on SEA → SFO from 2025-07-01 to 2026-06-30, DL3991 arrived within 15 minutes of schedule 72% of the time. The median arrival delay was 0 min, and the worst 10% of flights arrived +53 min or later. 1% of flights were cancelled.

Delay distribution

Arrival delay for completed flights (excludes cancellations and diversions).

ArrivalFlightsShare
Early / on-time21072%
16-30 min2810%
31-60 min3010%
61-120 min155%
2+ hrs72%

Performance by month

MonthFlightsOn-timeAvg delay
2025-072993%-3 min
2025-082986%+6 min
2025-092365%+11 min
2025-102781%+4 min
2025-112568%+5 min
2025-121989%-4 min
2026-011392%-7 min
2026-021164%+13 min
2026-032378%+4 min
2026-043077%+15 min
2026-053148%+22 min
2026-063040%+43 min

Performance by day of week

DayFlightsOn-time
Mon4480%
Tue4475%
Wed4372%
Thu4274%
Fri3962%
Sat3580%
Sun4365%

Based on US Department of Transportation Bureau of Transportation Statistics on-time data. Loading live conditions and full charts…