About 1 in 3 AS 520 flights from Seattle arrived 15+ minutes late, diverted or cancelled over the past year (33%); 0.0% were cancelled. The typical flight landed 1 minutes late.
AS 520: SEA → SAT
Scheduled to leave Seattle at 10:58 p.m. local time. Over the past year it arrived on time 67% of the time (123 flights), better than other AS flights on the route at that hour (58%). Last seen in the data Aug 17, 2026.
Usually Alaska Airlines's last flight of the day from Seattle to San Antonio (100% of days). Alaska Airlines's last SEA–SAT flight was cancelled 0.5% of the time, against 1.6% for its earlier ones. If it's cancelled, the next Alaska Airlines flight is usually around 9:38 a.m. the next morning.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 19 | — |
| Tuesday | 16 | — |
| Wednesday | 15 | — |
| Thursday | 17 | — |
| Friday | 19 | — |
| Saturday | 18 | — |
| Sunday | 19 | — |
Why it was late
All flights SEA → SAT · Connecting off AS 520? Check the risk
Questions
How often is AS 520 from SEA to SAT late?
Alaska Airlines 520 from Seattle, WA to San Antonio, TX arrived 15 or more minutes late, was diverted or was cancelled on 33% of 123 scheduled flights between September 2025 and August 2026. 0.0% 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.