WN4535
WN4535 (Southwest Airlines) is a multi-stop service on 15 routes, busiest Baltimore to Louisville. Of 436 departures recorded from October 2024 to July 2026, 70.1% left on time, according to the US BTS.
- On-time departures70.1%of 436 flights
- Average delay15.4 min
- July 202631
- Cancelled1.2%
- Legs flown under this number15
Recorded departures by month
All legs under this number combined; see the leg table.
Months without data are left blank.
The most recent periods18 periods
| Period | Departures 2025 | Departures 2026 | Change vs last year |
|---|---|---|---|
| January | 29 | 6 | ▼ 79.3% |
| February | 20 | 1 | ▼ 95.0% |
| March | 12 | 27 | ▲ 125.0% |
| April | 19 | 33 | ▲ 73.7% |
| May | 22 | 35 | ▲ 59.1% |
| June | 3 | 30 | ▲ 900.0% |
| July | – | 31 | – |
| August | 3 | – | – |
| September | 4 | – | – |
| October | 29 | – | in progress |
| November | 40 | – | – |
| December | 35 | – | – |
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 periods18 periods
| Period | On time 2025 | On time 2026 | Change vs last year |
|---|---|---|---|
| January | 82.1% | 66.7% | ▼ 18.8% |
| February | 95.0% | 0.0% | ▼ 100.0% |
| March | 83.3% | 53.9% | ▼ 35.4% |
| April | 79.0% | 81.8% | ▲ 3.6% |
| May | 54.6% | 62.9% | ▲ 15.2% |
| June | 66.7% | 46.7% | ▼ 30.0% |
| July | – | 54.8% | – |
| August | 100.0% | – | – |
| September | 100.0% | – | – |
| October | 69.0% | – | in progress |
| November | 83.8% | – | – |
| December | 77.1% | – | – |
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 periods18 periods
| Period | Cancelled 2025 | Cancelled 2026 | Change vs last year |
|---|---|---|---|
| January | 1 | 0 | ▼ 100.0% |
| February | 0 | 0 | – |
| March | 0 | 1 | – |
| April | 0 | 0 | – |
| May | 0 | 0 | – |
| June | 0 | 0 | – |
| July | – | 0 | – |
| August | 0 | – | – |
| September | 0 | – | – |
| October | 0 | – | in progress |
| November | 3 | – | – |
| 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 98.9% 431
- Cancelled 1.1% 5
Share of all recorded flights in the period, all legs. · Oct 12, 2024 → Jul 31, 2026
On time, leg by leg
Departures within 15 minutes of schedule; small figure = departures recorded.
Legs flown under this number
8| Routes | Distance (km) | Avg delay | On time | Departures |
|---|---|---|---|---|
| BWI SDF Baltimore/Washington International Thurgood Marshall Airport – Louisville Muhammad Ali International Airport | 795 | 11.9 min | 77.7% | 86 |
| GSP BNA Greenville-Spartanburg International Airport – Nashville International Airport | 426 | 22.0 min | 53.5% | 58 |
| TPA BNA Tampa International Airport – Nashville International Airport | 987 | 17.6 min | 71.9% | 57 |
| MCO MDW Orlando International Airport – Chicago Midway International Airport | 1,595 | 2.2 min | 93.0% | 44 |
| BUR SMF Hollywood Burbank/Bob Hope Airport – Sacramento International Airport | 577 | 13.4 min | 66.7% | 42 |
| MDW DEN Chicago Midway International Airport – Denver International Airport | 1,438 | 18.3 min | 61.8% | 36 |
| STL ATL St. Louis Lambert International Airport – Hartsfield Jackson Atlanta International Airport | 779 | 25.2 min | 59.4% | 33 |
| SMF SAN Sacramento International Airport – San Diego International Airport | 773 | 17.7 min | 70.0% | 30 |
Monthly figures
| Period | Departures | With departure delay recorded | On time | Cancelled |
|---|---|---|---|---|
| October 2024 | 19 | 19 | 73.7% | 0 |
| November 2024 | 21 | 21 | 66.7% | 0 |
| December 2024 | 17 | 17 | 58.8% | 0 |
| January 2025 | 29 | 28 | 82.1% | 1 |
| February 2025 | 20 | 20 | 95.0% | 0 |
| March 2025 | 12 | 12 | 83.3% | 0 |
| April 2025 | 19 | 19 | 79.0% | 0 |
| May 2025 | 22 | 22 | 54.6% | 0 |
| June 2025 | 3 | 3 | 66.7% | 0 |
| August 2025 | 3 | 3 | 100.0% | 0 |
| September 2025 | 4 | 4 | 100.0% | 0 |
| October 2025 | 29 | 29 | 69.0% | 0 |
| November 2025 | 40 | 37 | 83.8% | 3 |
| December 2025 | 35 | 35 | 77.1% | 0 |
| January 2026 | 6 | 6 | 66.7% | 0 |
| February 2026 | 1 | 1 | 0.0% | 0 |
| March 2026 | 27 | 26 | 53.9% | 1 |
| April 2026 | 33 | 33 | 81.8% | 0 |
| May 2026 | 35 | 35 | 62.9% | 0 |
| June 2026 | 30 | 30 | 46.7% | 0 |
| July 2026 | 31 | 31 | 54.8% | 0 |