Flight AS521
Alaska Airlines flight AS521
Looking for AS521 in the air…
Seattle (SEA) to San Jose (SJC)
Historically, this flight arrives 15+ minutes late 14% of the time, and when it is late the delay averages 61 minutes. It was cancelled 1.0% of the time.
- On-time arrivals
- 85.6%
- Less than 15 minutes late
- Cancelled
- 1.0%
- Of scheduled flights
- Average delay when late
- 61 min
- Flights arriving 15+ minutes late
- Flights tracked
- 197
- Scheduled flights in the period
What caused the delays
- Airline (crew, maintenance, cleaning) 51%
- Late-arriving aircraft 45%
- Air traffic control & airport 5%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Jose (SJC) to Seattle (SEA)
Historically, this flight arrives 15+ minutes late 25% of the time, and when it is late the delay averages 55 minutes. It was cancelled 1.4% of the time.
- On-time arrivals
- 75.4%
- Less than 15 minutes late
- Cancelled
- 1.4%
- Of scheduled flights
- Average delay when late
- 55 min
- Flights arriving 15+ minutes late
- Flights tracked
- 70
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 76%
- Air traffic control & airport 14%
- Airline (crew, maintenance, cleaning) 10%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Nashville (BNA) to Seattle (SEA)
Historically, this flight arrives 15+ minutes late 48% of the time, and when it is late the delay averages 46 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 51.5%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 46 min
- Flights arriving 15+ minutes late
- Flights tracked
- 33
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 47%
- Air traffic control & airport 21%
- Airline (crew, maintenance, cleaning) 19%
- Extreme weather 13%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Show as table
| Month | On time | Flights |
|---|---|---|
| September 2025 | 50.0% | 30 |
| October 2025 | 88.9% | 9 |
| November 2025 | 94.1% | 17 |
| December 2025 | 83.3% | 12 |
| January 2026 | 80.0% | 26 |
| February 2026 | 78.6% | 28 |
| March 2026 | 85.7% | 29 |
| April 2026 | 92.3% | 26 |
| May 2026 | 87.1% | 31 |
| June 2026 | 82.8% | 30 |
| July 2026 | 71.0% | 31 |
| August 2026 | 77.4% | 31 |
Source: U.S. DOT Bureau of Transportation Statistics on-time data, September 2025 – August 2026. Covers flights operated by reporting U.S. carriers. About our data