WN1821
WN1821 (Southwest Airlines) is a multi-stop service on 27 routes, busiest Denver to Boise. Of 655 departures recorded from October 2024 to July 2026, 72.4% left on time, according to the US BTS.
- On-time departures72.4%of 655 flights
- Average delay14.5 min
- July 202611▼ 59.3%vs July 2025
- Cancelled0.5%
- Legs flown under this number27
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 | 37 | 30 | ▼ 18.9% |
| February | 35 | 56 | ▲ 60.0% |
| March | 32 | 47 | ▲ 46.9% |
| April | 22 | 33 | ▲ 50.0% |
| May | 23 | 31 | ▲ 34.8% |
| June | 24 | 10 | ▼ 58.3% |
| July | 27 | 11 | ▼ 59.3% |
| August | 22 | – | – |
| September | 21 | – | – |
| October | 30 | – | in progress |
| November | 28 | – | – |
| December | 29 | – | – |
| Year to date (Jan–Jul) | 200 | 218 | ▲ 9.0% |
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 | 73.0% | 86.7% | ▲ 18.8% |
| February | 82.9% | 70.9% | ▼ 14.4% |
| March | 90.6% | 63.8% | ▼ 29.6% |
| April | 71.4% | 81.8% | ▲ 14.5% |
| May | 81.8% | 90.3% | ▲ 10.4% |
| June | 41.7% | 100.0% | ▲ 140.0% |
| July | 48.2% | 81.8% | ▲ 69.9% |
| August | 54.6% | – | – |
| September | 76.2% | – | – |
| October | 76.7% | – | in progress |
| November | 60.7% | – | – |
| December | 41.4% | – | – |
| Year-to-date average (Jan–Jul) | 69.9% | 82.2% | ▲ 17.5% |
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 | 1 | – |
| March | 0 | 0 | – |
| April | 1 | 0 | ▼ 100.0% |
| May | 1 | 0 | ▼ 100.0% |
| June | 0 | 0 | – |
| July | 0 | 0 | – |
| August | 0 | – | – |
| September | 0 | – | – |
| October | 0 | – | in progress |
| November | 0 | – | – |
| December | 0 | – | – |
| Year to date (Jan–Jul) | 2 | 1 | ▼ 50.0% |
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 99.5% 652
- Cancelled 0.5% 3
Share of all recorded flights in the period, all legs. · Oct 12, 2024 → Jul 29, 2026
On time, leg by leg
Departures within 15 minutes of schedule; small figure = departures recorded.
Legs flown under this number
11Monthly figures
| Period | Departures | With departure delay recorded | On time | Cancelled |
|---|---|---|---|---|
| October 2024 | 29 | 29 | 75.9% | 0 |
| November 2024 | 36 | 36 | 86.1% | 0 |
| December 2024 | 42 | 42 | 69.1% | 0 |
| January 2025 | 37 | 37 | 73.0% | 0 |
| February 2025 | 35 | 35 | 82.9% | 0 |
| March 2025 | 32 | 32 | 90.6% | 0 |
| April 2025 | 22 | 21 | 71.4% | 1 |
| May 2025 | 23 | 22 | 81.8% | 1 |
| June 2025 | 24 | 24 | 41.7% | 0 |
| July 2025 | 27 | 27 | 48.2% | 0 |
| August 2025 | 22 | 22 | 54.6% | 0 |
| September 2025 | 21 | 21 | 76.2% | 0 |
| October 2025 | 30 | 30 | 76.7% | 0 |
| November 2025 | 28 | 28 | 60.7% | 0 |
| December 2025 | 29 | 29 | 41.4% | 0 |
| January 2026 | 30 | 30 | 86.7% | 0 |
| February 2026 | 56 | 55 | 70.9% | 1 |
| March 2026 | 47 | 47 | 63.8% | 0 |
| April 2026 | 33 | 33 | 81.8% | 0 |
| May 2026 | 31 | 31 | 90.3% | 0 |
| June 2026 | 10 | 10 | 100.0% | 0 |
| July 2026 | 11 | 11 | 81.8% | 0 |