Carrier route record
YXORD→BUF
Republic Airways · Chicago to Buffalo
- Flights
- 355
- Period
- July 2025 to June 2026
- Share of route
- 16%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Republic Airways.
Republic on ORD to BUF sits in the middle of the pack with a C−. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 355 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 422 at 79.8% on time.
Envoy Air is the most reliable of the three carriers covered here at 79.8% on time across 422 flights.
Key figures
On time
74.3%
Arrivals under 15 minutes late, of 335 completed flights
Avg delay
74 min
Across delayed arrivals only, not all flights
Cancelled
5.07%
National rate is 1.81%
Whole route
70.6%
Every carrier on ORD to BUF, 2,195 flights
These figures cover 355 flights between July 2025 and June 2026. Beyond the headline rate, 9.0% 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
Republic against every carrier on ORD to BUF
Republic flew 355 of the 2,195 flights on ORD to BUF, about 16% of it. Its 74.3% on time is 4 points better than the route as a whole, which runs 70.6%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from Envoy at 79.8% to American at 58.8%. One 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; American Airlines manages 58.8%. Sample sizes sit next to every figure, because a two-point gap across 476 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 Airways (this page)thin 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 | 476 | 58.8% | 88 min | 1.26% | D |
The spread between Envoy and American is 21 points, wide enough that it should decide the booking. On a hundred trips that is 21 more arrivals inside the on-time window.
Departure window
When Republic runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 37 points, against 21 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am61 flights91.7%
- 8am–11am44 flights79.1%
- 11am–2pm1 flights—
- 2pm–5pm130 flights77.7%
- 5pm–8pm32 flights71.0%
- 8pm–5am87 flights54.4%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 54.4% on time, against 91.7% for the 5am–8am 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 2pm–5pm window is the busiest, with 130 flights scheduled in it.
Across the year
Republic on ORD to BUF through the year
- Jul–Sep 202516 flights—
- Oct–Dec 202554 flights63.3%
- Jan–Mar 2026173 flights70.1%
- Apr–Jun 2026112 flights83.0%
Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 74.3% on time across 355 flights.
Republic on ORD to BUF did not run the same all year. Its best quarter was Apr–Jun 2026 at 83.0% on time and its weakest Oct–Dec 2025 at 63.3%, a swing of 20 points on roughly 118 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
Across the week, Saturday is the strongest day at 86.1% on time and Wednesday the weakest at 66.7%. 19 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Republic runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 42% of the 6,370 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.
- 42%Late-arriving aircraft
- 24%Carrier
- 20%National Airspace System
- 13%Extreme weather
Extreme weather accounts for 13% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.2 times the usual weather exposure. The split is drawn from 6,370 reported delay minutes.
42% 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 6,370 reported delay minutes here, that single category outweighs weather by 3 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.
Cancellations run at 5.07%, against 1.81% nationally. That is about one flight in twenty cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
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. 9.0% 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 5am–8am window matters as much as it does.
The return leg runs 76.2% on time across 355 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 355 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 Republic on ORD to BUF
Put together: the delay figures matter less here than the 5.07% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 335 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to BUF, every carrier
- Republic on BUF to ORD, the return leg
- Envoy Air on ORD to BUF79.8%
- United Airlines on ORD to BUF73.8%
- SkyWest Airlines on ORD to BUF66.1%
- American Airlines on ORD to BUF58.8%
- Republic Airways network-wide record
- Chicago O'Hare International (ORD) delay statistics
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
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.