YX4539
YX4539 (Republic Airways) is a multi-stop service on 16 routes, busiest Chicago to Pittsburgh. Of 652 departures recorded from October 2024 to July 2026, 74.2% left on time, according to the US BTS.
- On-time departures74.2%of 652 flights
- Average delay17.0 min
- July 202631▲ 14.8%vs July 2025
- Cancelled4.3%
- Legs flown under this number16
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 | 26 | 36 | ▲ 38.5% |
| February | 26 | 45 | ▲ 73.1% |
| March | 31 | 62 | ▲ 100.0% |
| April | 26 | 33 | ▲ 26.9% |
| May | 26 | 30 | ▲ 15.4% |
| June | 4 | 30 | ▲ 650.0% |
| July | 27 | 31 | ▲ 14.8% |
| August | 31 | – | – |
| September | 30 | – | – |
| October | 30 | – | in progress |
| November | 28 | – | – |
| December | 29 | – | – |
| Year to date (Jan–Jul) | 166 | 267 | ▲ 60.8% |
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 | 80.8% | 67.7% | ▼ 16.2% |
| February | 69.2% | 77.8% | ▲ 12.4% |
| March | 90.3% | 64.9% | ▼ 28.1% |
| April | 73.1% | 80.0% | ▲ 9.5% |
| May | 68.0% | 75.0% | ▲ 10.3% |
| June | 100.0% | 71.4% | ▼ 28.6% |
| July | 33.3% | 63.0% | ▲ 88.9% |
| August | 76.7% | – | – |
| September | 90.0% | – | – |
| October | 73.3% | – | in progress |
| November | 70.4% | – | – |
| December | 70.4% | – | – |
| Year-to-date average (Jan–Jul) | 73.5% | 71.4% | ▼ 2.9% |
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 | 2 | – |
| February | 0 | 0 | – |
| March | 0 | 5 | – |
| April | 0 | 3 | – |
| May | 1 | 2 | ▲ 100.0% |
| June | 0 | 2 | – |
| July | 3 | 4 | ▲ 33.3% |
| August | 1 | – | – |
| September | 0 | – | – |
| October | 0 | – | in progress |
| November | 1 | – | – |
| December | 2 | – | – |
| Year to date (Jan–Jul) | 4 | 18 | ▲ 350.0% |
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 95.7% 624
- Cancelled 4.3% 28
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
7| Routes | Distance (km) | Avg delay | On time | Departures |
|---|---|---|---|---|
| ORD PIT Chicago O'Hare International Airport – Pittsburgh International Airport | 662 | 19.6 min | 66.9% | 163 |
| LGA RDU LaGuardia Airport – Raleigh-Durham International Airport | 693 | 23.4 min | 75.0% | 91 |
| ORD CID Chicago O'Hare International Airport – The Eastern Iowa Airport | 315 | 14.8 min | 74.7% | 84 |
| CID ORD The Eastern Iowa Airport – Chicago O'Hare International Airport | 315 | 29.7 min | 64.5% | 83 |
| IND PHL Indianapolis International Airport – Philadelphia International Airport | 944 | 9.2 min | 82.9% | 82 |
| SDF ORD Louisville Muhammad Ali International Airport – Chicago O'Hare International Airport | 462 | 16.8 min | 67.7% | 32 |
| BOS CMH Boston Logan International Airport – John Glenn Columbus International Airport | 1,028 | 22.8 min | 70.0% | 31 |
Monthly figures
| Period | Departures | With departure delay recorded | On time | Cancelled |
|---|---|---|---|---|
| October 2024 | 37 | 37 | 94.6% | 0 |
| November 2024 | 9 | 9 | 100.0% | 0 |
| December 2024 | 25 | 23 | 73.9% | 2 |
| January 2025 | 26 | 26 | 80.8% | 0 |
| February 2025 | 26 | 26 | 69.2% | 0 |
| March 2025 | 31 | 31 | 90.3% | 0 |
| April 2025 | 26 | 26 | 73.1% | 0 |
| May 2025 | 26 | 25 | 68.0% | 1 |
| June 2025 | 4 | 4 | 100.0% | 0 |
| July 2025 | 27 | 24 | 33.3% | 3 |
| August 2025 | 31 | 30 | 76.7% | 1 |
| September 2025 | 30 | 30 | 90.0% | 0 |
| October 2025 | 30 | 30 | 73.3% | 0 |
| November 2025 | 28 | 27 | 70.4% | 1 |
| December 2025 | 29 | 27 | 70.4% | 2 |
| January 2026 | 36 | 34 | 67.7% | 2 |
| February 2026 | 45 | 45 | 77.8% | 0 |
| March 2026 | 62 | 57 | 64.9% | 5 |
| April 2026 | 33 | 30 | 80.0% | 3 |
| May 2026 | 30 | 28 | 75.0% | 2 |
| June 2026 | 30 | 28 | 71.4% | 2 |
| July 2026 | 31 | 27 | 63.0% | 4 |