Airport Tips & Quick Reference Guide to Seattle–Tacoma Airport - Seatac (SEA)

AS521 Alaska Airlines - Flight Status

Codeshare Flights
The flight JL6310 from JAL (JL) is a codeshare flight operated by Alaska Airlines (AS) under the flight number AS521. Check this page for details about flight AS521.

Below, you can find details about Alaska Airlines flight AS521, which currently operates between the airports of Seattle - Seattle-Tacoma International Airport (Airport Code SEA) and San Jose - San Jose Mineta International Airport (Airport Code SJC).
This flight data pertains specifically to the flight's details for Thursday, May 21, 2026.

AS521 On Time performance:
86
We have calculated the percentage of flights that arrived within 15 minutes of their scheduled time, or earlier, based on real flight data from the last 3 months. More about punctuality and delays

Flight Status

AS521 Alaska Airlines to San Jose

Scheduled - On-time
Flight Status for Thursday May 21, 2026
This flight was also scheduled for Yesterday (May 19, 2026). See it here
This flight is also scheduled for Today (May 20, 2026). See it here

Airline information

Alaska Airlines
Alaska Airlines
Equipment: Boeing 737MAX 9 Passenger

Departure

Seattle (SEA)
May 21, 2026
Seattle-Tacoma International Airport
Estimated Departure Time:
02:54 pm
Gate:
C20
Scheduled Departure Time: 02:54 pm

Arrival

San Jose (SJC)
May 21, 2026
San Jose Mineta International Airport
Estimated Arrival Time:
05:06 pm
Terminal:
B
Gate:
32
Scheduled Arrival Time: 05:06 pm
Baggage: B1
Disclaimer
The information displayed on this website is gathered from third-party providers with a wide reputation on the sector, which in turn obtain the information from the airlines. This data is provided only for informative purposes. www.seattle-airport.com assumes no responsibility for loss or damage as a result of relying on information posted here. Please contact your airline to verify flight status.

Codeshare Flights

This flight is shared with other airlines, this means that these other flights are the same:

- AA7505 - American Airlines

- FI7665 - Icelandair

- JL6310 - JAL

Additional Information

Which is the frequency of flight AS521?
The flight AS521 is scheduled to flight on daily basis.

Which is the distance of flight AS521?
The distance between the two airports is 697 miles.

Which is the flight time of flight AS521?
The scheduled flight time gate to gate is: 02:12 hours.
The real flight time gate to gate on average is: 02:06 hours.

Are the departure airport and arrival airport at the same Time Zone?
Yes, both airports are in the same timezone.

Alternative Flights

The following airlines serves the same route between Seattle and San Jose:

Alaska Airlines
- Flight Number: AS1303. (On Time performance: 82 - Average Delay: 8 minutes)
- Flight Number: AS1341. (On Time performance: 91 - Average Delay: 5 minutes)
- Flight Number: AS2186. (On Time performance: 100 - Average Delay: 0 minutes)
- Flight Number: AS335. (On Time performance: 90 - Average Delay: 4 minutes)
- Flight Number: AS582. (On Time performance: 86 - Average Delay: 4 minutes)
- Flight Number: AS657. (On Time performance: 87 - Average Delay: 8 minutes)
- Flight Number: AS761. (On Time performance: 79 - Average Delay: 12 minutes)

Delta Air Lines
- Flight Number: DL3736. (On Time performance: 94 - Average Delay: 7 minutes)
- Flight Number: DL3789. (On Time performance: 89 - Average Delay: 6 minutes)
- Flight Number: DL3897. (On Time performance: 82 - Average Delay: 10 minutes)
- Flight Number: DL3956. (On Time performance: 86 - Average Delay: 9 minutes)
- Flight Number: DL4100. (On Time performance: 84 - Average Delay: 9 minutes)
- Flight Number: DL4132. (On Time performance: 79 - Average Delay: 8 minutes)

Southwest Airlines
- Flight Number: WN2089. (On Time performance: 61 - Average Delay: 15 minutes)
- Flight Number: WN2841. (On Time performance: 92 - Average Delay: 2 minutes)
- Flight Number: WN4201. (On Time performance: 100 - Average Delay: 0 minutes)

Punctuality and delays

We have gathered data from recent months and present below an analysis of how timely the flights have been.

In terms of On-Time Performance, by analyzing the flight data from the last three months, spanning from February 18, 2026 to May 17, 2026, we have obtained these figures.
Total number of flights: 83
On Time: 71 ( 86 % )
Moderate Delay: 4 ( 5 % )
Significant Delay: 3 ( 4 % )
Major Delay: 5 ( 6 % )
Canceled: 0 ( 0 % )
Diverted: 0 ( 0 % )

Average Delay: 11 minutes.
Delays analyzed by Weekday: We have gathered available data from last six months, spanning from November 18, 2025 to May 17, 2026. Next, you can observe the results broken down by day of the week: number of flights analyzed, on-time performance per day, and average delay per day.

Delays analyzed by Month: We have gathered available data from last twelve closed months, spanning from October 26, 2025 to April 30, 2026. Next, you can observe the results broken down by month: number of flights analyzed, on-time performance per month, and average delay per month.

Last Past Flights AS521

Date
Departure
Arrival
Duration
Aircraft
Status
Tuesday
19 May
02:50 pm
Seattle (SEA)
04:41 pm
San Jose (SJC)
01h 51min
Boeing 737-900
Boeing 737-900
Landed - On-time
Monday
18 May
03:14 pm
Seattle (SEA)
05:03 pm
San Jose (SJC)
01h 49min
Boeing 737MAX
Boeing 737MAX
Landed - On-time
Sunday
17 May
03:02 pm
Seattle (SEA)
05:00 pm
San Jose (SJC)
01h 58min
Boeing 737-800
Boeing 737-800
Landed - On-time
Saturday
16 May
02:50 pm
Seattle (SEA)
04:49 pm
San Jose (SJC)
01h 59min
Boeing 737-800
Boeing 737-800
Landed - On-time
Friday
15 May
03:12 pm
Seattle (SEA)
05:16 pm
San Jose (SJC)
02h 04min
Boeing 737-900
Boeing 737-900
Landed - On-time
Thursday
14 May
03:01 pm
Seattle (SEA)
05:03 pm
San Jose (SJC)
02h 02min
Boeing 737-900
Boeing 737-900
Landed - On-time
Wednesday
13 May
02:56 pm
Seattle (SEA)
04:57 pm
San Jose (SJC)
02h 01min
Boeing 737-900
Boeing 737-900
Landed - On-time
Tuesday
12 May
04:25 pm
Seattle (SEA)
06:45 pm
San Jose (SJC)
02h 20min
Boeing 737-800
Boeing 737-800
Landed - On-time
Monday
11 May
04:21 pm
Seattle (SEA)
06:31 pm
San Jose (SJC)
02h 10min
Boeing 737-900
Boeing 737-900
Landed - On-time
Sunday
10 May
04:26 pm
Seattle (SEA)
06:38 pm
San Jose (SJC)
02h 12min
Boeing 737-900
Boeing 737-900
Landed - On-time