Carrier route record
AAORD→BUF
American Airlines · Chicago to Buffalo
- Flights
- 476
- Period
- July 2025 to June 2026
- Share of route
- 22%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with American Airlines.
American on ORD to BUF draws a D. Roughly one flight in two arrives at least 15 minutes late, and the typical late arrival is an hour and a half behind schedule. Build slack into anything you connect to. That rests on 476 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 422 at 79.8% on time.
The national on-time rate over the same period is 77.6%, so American on ORD to BUF runs 19 points behind the country as a whole. Across a thousand flights that is about 188 extra late arrivals.
Key figures
On time
58.8%
Arrivals under 15 minutes late, of 469 completed flights
Avg delay
88 min
Across delayed arrivals only, not all flights
Cancelled
1.26%
National rate is 1.81%
Whole route
70.6%
Every carrier on ORD to BUF, 2,195 flights
These figures cover 476 flights between July 2025 and June 2026. Beyond the headline rate, 18.3% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
American against every carrier on ORD to BUF
American flew 476 of the 2,195 flights on ORD to BUF, about 22% of it. Its 58.8% on time is 12 points worse than the route as a whole, which runs 70.6%. Ranked by on-time rate it is last of five carriers on the route, where the range runs from Envoy at 79.8% to American at 58.8%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. Envoy Air arrives on time 79.8% of the time; United Airlines manages 73.8%. Sample sizes sit next to every figure, because a two-point gap across 612 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 422 | 79.8% | 60 min | 2.61% | B |
| Republic Airwaysthin sample | 355 | 74.3% | 74 min | 5.07% | C− |
| United Airlines | 612 | 73.8% | 81 min | 1.14% | C |
| SkyWest Airlinesthin sample | 330 | 66.1% | 84 min | 4.85% | C− |
| American Airlines (this page) | 476 | 58.8% | 88 min | 1.26% | D |
Envoy leads United by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Departure window
When American runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 38 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am79 flights84.8%
- 11am–2pm48 flights78.7%
- 2pm–5pm10 flights—
- 5pm–8pm197 flights51.5%
- 8pm–5am142 flights46.8%
Scale runs 40% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 46.8% on time, against 84.8% for the 8am–11am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5pm–8pm window is the busiest, with 197 flights scheduled in it.
Across the year
American on ORD to BUF through the year
July is the worst month at 37.1% on time, 35 points below September, the best at 72.1%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. May was the busiest month here, with 82 flights.
Across the week, Tuesday is the strongest day at 66.7% on time and Sunday the weakest at 52.2%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why American runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 62% of the 17,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 62%Late-arriving aircraft
- 23%Carrier
- 8%National Airspace System
- 7%Extreme weather
62% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 17,000 reported delay minutes here, that single category outweighs weather by 9 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 16,882 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 84.8% on time here.
Cancellations sit at 1.26% against a national 1.81%, which is ordinary. Diversions add another 0.21%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 18.3% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
At 474 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 8am–11am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 84.0% on time across 476 flights, 25 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 25 points of difference.
One caution: this is a thin sample. 476 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking American on ORD to BUF
Put together: treat all of this as provisional. 476 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 58.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 469 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to BUF, every carrier
- American on BUF to ORD, the return leg
- Envoy Air on ORD to BUF79.8%
- Republic Airways on ORD to BUF74.3%
- United Airlines on ORD to BUF73.8%
- SkyWest Airlines on ORD to BUF66.1%
- American Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.