WN4239
WN4239 (Southwest Airlines) is a multi-stop service on 18 routes, busiest Baltimore to Boston. Of 238 departures recorded from October 2024 to July 2026, 69.4% left on time, according to the US BTS.
- On-time departures69.4%of 238 flights
- Average delay14.6 min
- July 202626▲ 225.0%vs July 2025
- Cancelled1.3%
- Legs flown under this number18
Recorded departures by month
All legs under this number combined; see the leg table.
Months without data are left blank.
The most recent periods16 periods
| Period | Departures 2025 | Departures 2026 | Change vs last year |
|---|---|---|---|
| January | 19 | 3 | ▼ 84.2% |
| February | 19 | – | – |
| March | 4 | 43 | ▲ 975.0% |
| April | 6 | 10 | ▲ 66.7% |
| May | 9 | – | – |
| June | 9 | 19 | ▲ 111.1% |
| July | 8 | 26 | ▲ 225.0% |
| August | 2 | – | – |
| September | 1 | – | – |
| October | – | – | in progress |
| November | 3 | – | – |
| December | 10 | – | – |
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 periods16 periods
| Period | On time 2025 | On time 2026 | Change vs last year |
|---|---|---|---|
| January | 83.3% | 0.0% | ▼ 100.0% |
| February | 79.0% | – | – |
| March | 75.0% | 46.5% | ▼ 38.0% |
| April | 83.3% | 60.0% | ▼ 28.0% |
| May | 88.9% | – | – |
| June | 33.3% | 82.4% | ▲ 147.1% |
| July | 37.5% | 84.6% | ▲ 125.7% |
| August | 0.0% | – | – |
| September | 100.0% | – | – |
| October | – | – | in progress |
| November | 66.7% | – | – |
| December | 40.0% | – | – |
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 periods16 periods
| Period | Cancelled 2025 | Cancelled 2026 | Change vs last year |
|---|---|---|---|
| January | 1 | 0 | ▼ 100.0% |
| February | 0 | – | – |
| March | 0 | 0 | – |
| April | 0 | 0 | – |
| May | 0 | – | – |
| June | 0 | 2 | – |
| July | 0 | 0 | – |
| August | 0 | – | – |
| September | 0 | – | – |
| October | – | – | in progress |
| November | 0 | – | – |
| 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 98.7% 235
- Cancelled 1.3% 3
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
3| Routes | Distance (km) | Avg delay | On time | Departures |
|---|---|---|---|---|
| BWI BOS Baltimore/Washington International Thurgood Marshall Airport – Boston Logan International Airport | 594 | 10.1 min | 81.7% | 61 |
| SFO SAN San Francisco International Airport – San Diego International Airport | 719 | 6.4 min | 82.5% | 42 |
| PHX OMA Phoenix Sky Harbor International Airport – Eppley Airfield | 1,667 | 22.2 min | 51.5% | 33 |
Monthly figures
| Period | Departures | With departure delay recorded | On time | Cancelled |
|---|---|---|---|---|
| October 2024 | 20 | 20 | 90.0% | 0 |
| November 2024 | 10 | 10 | 90.0% | 0 |
| December 2024 | 17 | 17 | 88.2% | 0 |
| January 2025 | 19 | 18 | 83.3% | 1 |
| February 2025 | 19 | 19 | 79.0% | 0 |
| March 2025 | 4 | 4 | 75.0% | 0 |
| April 2025 | 6 | 6 | 83.3% | 0 |
| May 2025 | 9 | 9 | 88.9% | 0 |
| June 2025 | 9 | 9 | 33.3% | 0 |
| July 2025 | 8 | 8 | 37.5% | 0 |
| August 2025 | 2 | 2 | 0.0% | 0 |
| September 2025 | 1 | 1 | 100.0% | 0 |
| November 2025 | 3 | 3 | 66.7% | 0 |
| December 2025 | 10 | 10 | 40.0% | 0 |
| January 2026 | 3 | 3 | 0.0% | 0 |
| March 2026 | 43 | 43 | 46.5% | 0 |
| April 2026 | 10 | 10 | 60.0% | 0 |
| June 2026 | 19 | 17 | 82.4% | 2 |
| July 2026 | 26 | 26 | 84.6% | 0 |