About 1 in 4 AS 621 flights from Seattle arrived 15+ minutes late, diverted or cancelled over the past year (23%); 0.5% were cancelled. The typical flight landed 3 minutes early.
AS 621: SEA → SAN
Scheduled to leave Seattle at 12:41 p.m. local time. Over the past year it arrived on time 77% of the time (186 flights), better than other AS flights on the route at that hour (66%). Last seen in the data Aug 31, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 30 | 67% |
| Tuesday | 29 | 93% |
| Wednesday | 29 | 79% |
| Thursday | 29 | 79% |
| Friday | 18 | — |
| Saturday | 21 | 86% |
| Sunday | 30 | 63% |
Why it was late
All flights SEA → SAN · Connecting off AS 621? Check the risk
Questions
How often is AS 621 from SEA to SAN late?
Alaska Airlines 621 from Seattle, WA to San Diego, CA arrived 15 or more minutes late, was diverted or was cancelled on 23% of 186 scheduled flights between September 2025 and August 2026. 0.5% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check Alaska Airlines for today's flight. Method.