WN3521
WN3521 (Southwest Airlines) is a multi-stop service on 28 routes, busiest Chicago to Seattle. Of 367 departures recorded from October 2024 to July 2026, 77.4% left on time, according to the US BTS.
- On-time departures77.4%of 367 flights
- Average delay12.9 min
- July 202628▲ 460.0%vs July 2025
- Cancelled0.0%
- Legs flown under this number28
Recorded departures by month
All legs under this number combined; see the leg table.
The most recent periods19 periods
| Period | Departures 2025 | Departures 2026 | Change vs last year |
|---|---|---|---|
| January | 10 | 4 | ▼ 60.0% |
| February | 7 | 3 | ▼ 57.1% |
| March | 17 | 11 | ▼ 35.3% |
| April | 22 | 32 | ▲ 45.5% |
| May | 27 | 39 | ▲ 44.4% |
| June | 6 | 29 | ▲ 383.3% |
| July | 5 | 28 | ▲ 460.0% |
| August | 5 | – | – |
| September | 4 | – | – |
| October | 39 | – | in progress |
| November | 19 | – | – |
| December | 15 | – | – |
| Year to date (Jan–Jul) | 94 | 146 | ▲ 55.3% |
according to the US BTS · October 2024 → July 2026
On-time departures by month
On time = departure within 15 minutes of schedule. Non-cancelled flights with a recorded delay only.
The most recent periods19 periods
| Period | On time 2025 | On time 2026 | Change vs last year |
|---|---|---|---|
| January | 70.0% | 50.0% | ▼ 28.6% |
| February | 100.0% | 100.0% | 0.0% |
| March | 82.4% | 81.8% | ▼ 0.6% |
| April | 81.8% | 81.3% | ▼ 0.7% |
| May | 85.2% | 79.5% | ▼ 6.7% |
| June | 33.3% | 79.3% | ▲ 138.0% |
| July | 40.0% | 100.0% | ▲ 150.0% |
| August | 80.0% | – | – |
| September | 75.0% | – | – |
| October | 64.1% | – | in progress |
| November | 68.4% | – | – |
| December | 40.0% | – | – |
| Year-to-date average (Jan–Jul) | 70.4% | 81.7% | ▲ 16.1% |
according to the US BTS · October 2024 → July 2026
Average departure delay by month
according to the US BTS · October 2024 → July 2026
Cancelled departures by month
The most recent periods19 periods
| Period | Cancelled 2025 | Cancelled 2026 | Change vs last year |
|---|---|---|---|
| January | 0 | 0 | – |
| February | 0 | 0 | – |
| March | 0 | 0 | – |
| April | 0 | 0 | – |
| May | 0 | 0 | – |
| June | 0 | 0 | – |
| July | 0 | 0 | – |
| August | 0 | – | – |
| September | 0 | – | – |
| October | 0 | – | in progress |
| November | 0 | – | – |
| December | 0 | – | – |
| Year to date (Jan–Jul) | 0 | 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 100.0% 367
- Cancelled 0.0% 0
Share of all recorded flights in the period, all legs. · Oct 14, 2024 → Jul 29, 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 |
|---|---|---|---|---|
| MDW SEA Chicago Midway International Airport – Seattle–Tacoma International Airport | 2,782 | 8.6 min | 84.5% | 58 |
| TPA MDW Tampa International Airport – Chicago Midway International Airport | 1,607 | 5.7 min | 87.2% | 39 |
| MCI LAS Kansas City International Airport – Harry Reid International Airport | 1,829 | 26.7 min | 52.8% | 36 |
Monthly figures
| Period | Departures | With departure delay recorded | On time | Cancelled |
|---|---|---|---|---|
| October 2024 | 8 | 8 | 100.0% | 0 |
| November 2024 | 13 | 13 | 84.6% | 0 |
| December 2024 | 24 | 24 | 79.2% | 0 |
| January 2025 | 10 | 10 | 70.0% | 0 |
| February 2025 | 7 | 7 | 100.0% | 0 |
| March 2025 | 17 | 17 | 82.4% | 0 |
| April 2025 | 22 | 22 | 81.8% | 0 |
| May 2025 | 27 | 27 | 85.2% | 0 |
| June 2025 | 6 | 6 | 33.3% | 0 |
| July 2025 | 5 | 5 | 40.0% | 0 |
| August 2025 | 5 | 5 | 80.0% | 0 |
| September 2025 | 4 | 4 | 75.0% | 0 |
| October 2025 | 39 | 39 | 64.1% | 0 |
| November 2025 | 19 | 19 | 68.4% | 0 |
| December 2025 | 15 | 15 | 40.0% | 0 |
| January 2026 | 4 | 4 | 50.0% | 0 |
| February 2026 | 3 | 3 | 100.0% | 0 |
| March 2026 | 11 | 11 | 81.8% | 0 |
| April 2026 | 32 | 32 | 81.3% | 0 |
| May 2026 | 39 | 39 | 79.5% | 0 |
| June 2026 | 29 | 29 | 79.3% | 0 |
| July 2026 | 28 | 28 | 100.0% | 0 |