About 1 in 5 AA 4391 flights from Portland arrived 15+ minutes late, diverted or cancelled over the past year (19%); 3.0% were cancelled. The typical flight landed 10 minutes early.
AA 4391: PWM → ORD
Scheduled to leave Portland at 6:00 a.m. local time, operated by Republic Airways as YX 4391. Over the past year it arrived on time 81% of the time (135 flights), in line with other AA flights on the route at that hour (82%). Last seen in the data Aug 4, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 19 | — |
| Tuesday | 19 | — |
| Wednesday | 19 | — |
| Thursday | 19 | — |
| Friday | 20 | 95% |
| Saturday | 20 | 65% |
| Sunday | 19 | — |
Why it was late
All flights PWM → ORD · Connecting off AA 4391? Check the risk
Questions
How often is AA 4391 from PWM to ORD late?
American Airlines 4391 from Portland, ME to Chicago, IL arrived 15 or more minutes late, was diverted or was cancelled on 19% of 135 scheduled flights between September 2025 and August 2026. 3.0% 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.