AS521
AS521 (Alaska Airlines) is a multi-stop service on 7 routes, busiest Seattle to San Jose. Of 322 departures recorded from October 2024 to July 2026, 77.1% left on time, according to the US BTS.
- On-time departures77.1%of 322 flights
- Average delay9.7 min
- July 202631
- Cancelled0.9%
- Legs flown under this number7
Recorded departures by month
All legs under this number combined; see the leg table.
Months without data are left blank.
The most recent periods16 periods
| Period | Departures 2025 | Departures 2026 | Change vs last year |
|---|---|---|---|
| January | – | 26 | – |
| February | – | 28 | – |
| March | 1 | 29 | ▲ 2,800.0% |
| April | 1 | 26 | ▲ 2,500.0% |
| May | 19 | 31 | ▲ 63.2% |
| June | 11 | 30 | ▲ 172.7% |
| July | – | 31 | – |
| August | 12 | – | – |
| September | 30 | – | – |
| October | 9 | – | in progress |
| November | 17 | – | – |
| December | 12 | – | – |
according to the US BTS · October 2024 → July 2026
On-time departures by month
Months without data are left blank.
On time = departure within 15 minutes of schedule. Non-cancelled flights with a recorded delay only.
The most recent periods16 periods
| Period | On time 2025 | On time 2026 | Change vs last year |
|---|---|---|---|
| January | – | 84.0% | – |
| February | – | 85.7% | – |
| March | 100.0% | 67.9% | ▼ 32.1% |
| April | 100.0% | 88.5% | ▼ 11.5% |
| May | 79.0% | 77.4% | ▼ 1.9% |
| June | 90.9% | 79.3% | ▼ 12.8% |
| July | – | 51.6% | – |
| August | 83.3% | – | – |
| September | 53.3% | – | – |
| October | 100.0% | – | in progress |
| November | 94.1% | – | – |
| December | 75.0% | – | – |
according to the US BTS · October 2024 → July 2026
Average departure delay by month
Months without data are left blank.
according to the US BTS · October 2024 → July 2026
Cancelled departures by month
Months without data are left blank.
The most recent periods16 periods
| Period | Cancelled 2025 | Cancelled 2026 | Change vs last year |
|---|---|---|---|
| January | – | 1 | – |
| February | – | 0 | – |
| March | 0 | 1 | – |
| April | 0 | 0 | – |
| May | 0 | 0 | – |
| June | 0 | 1 | – |
| July | – | 0 | – |
| August | 0 | – | – |
| September | 0 | – | – |
| October | 0 | – | in progress |
| November | 0 | – | – |
| December | 0 | – | – |
according to the US BTS · October 2024 → July 2026
This is a historical record of departures already flown, not a forecast for your flight.
Several legs: the headline figure averages all of them. See the leg table.
Cancellation share
- Not cancelled 99.1% 319
- Cancelled 0.9% 3
Share of all recorded flights in the period, all legs. · Oct 13, 2024 → Jul 31, 2026
On time, leg by leg
Departures within 15 minutes of schedule; small figure = departures recorded.
Legs flown under this number
3| Routes | Distance (km) | Avg delay | On time | Departures |
|---|---|---|---|---|
| SEA SJC Seattle–Tacoma International Airport – Mineta San Jose International Airport | 1,122 | 7.3 min | 83.0% | 184 |
| SJC SEA Mineta San Jose International Airport – Seattle–Tacoma International Airport | 1,122 | 15.5 min | 58.8% | 52 |
| BNA SEA Nashville International Airport – Seattle–Tacoma International Airport | 3,176 | 19.3 min | 64.4% | 45 |
Monthly figures
| Period | Departures | With departure delay recorded | On time | Cancelled |
|---|---|---|---|---|
| October 2024 | 9 | 9 | 100.0% | 0 |
| March 2025 | 1 | 1 | 100.0% | 0 |
| April 2025 | 1 | 1 | 100.0% | 0 |
| May 2025 | 19 | 19 | 79.0% | 0 |
| June 2025 | 11 | 11 | 90.9% | 0 |
| August 2025 | 12 | 12 | 83.3% | 0 |
| September 2025 | 30 | 30 | 53.3% | 0 |
| October 2025 | 9 | 9 | 100.0% | 0 |
| November 2025 | 17 | 17 | 94.1% | 0 |
| December 2025 | 12 | 12 | 75.0% | 0 |
| January 2026 | 26 | 25 | 84.0% | 1 |
| February 2026 | 28 | 28 | 85.7% | 0 |
| March 2026 | 29 | 28 | 67.9% | 1 |
| April 2026 | 26 | 26 | 88.5% | 0 |
| May 2026 | 31 | 31 | 77.4% | 0 |
| June 2026 | 30 | 29 | 79.3% | 1 |
| July 2026 | 31 | 31 | 51.6% | 0 |