About 1 in 4 AA 4539 flights from Chicago arrived 15+ minutes late, diverted or cancelled over the past year (25%); 4.4% were cancelled. The typical flight landed 7 minutes early.
AA 4539: ORD → PIT
Scheduled to leave Chicago at 9:10 p.m. local time, operated by Republic Airways as YX 4539. Over the past year it arrived on time 75% of the time (135 flights), better than other AA flights on the route at that hour (65%). Last seen in the data Aug 4, 2026.
Usually American Airlines's last flight of the day from Chicago to Pittsburgh (82% of days). American Airlines's last ORD–PIT flight was cancelled 4.7% of the time, against 1.9% for its earlier ones. If it's cancelled, the next American Airlines flight is usually around 8:25 a.m. the next morning.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 19 | — |
| Tuesday | 19 | — |
| Wednesday | 19 | — |
| Thursday | 20 | 65% |
| Friday | 19 | — |
| Saturday | 20 | 80% |
| Sunday | 19 | — |
Why it was late
All flights ORD → PIT · Connecting off AA 4539? Check the risk
Questions
How often is AA 4539 from ORD to PIT late?
American Airlines 4539 from Chicago, IL to Pittsburgh, PA arrived 15 or more minutes late, was diverted or was cancelled on 25% of 135 scheduled flights between September 2025 and August 2026. 4.4% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check American Airlines for today's flight. Method.