Carrier route record
UABUF→ORD
United Airlines · Buffalo to Chicago
- Flights
- 612
- Period
- July 2025 to June 2026
- Share of route
- 28%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on BUF to ORD sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 612 flights. The strongest carrier on the route with a full sample, American Airlines, flew 476 at 84.0% on time.
The US average over the same twelve months is 77.6%, so there is little to separate United on BUF to ORD from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
74.1%
Arrivals under 15 minutes late, of 603 completed flights
Avg delay
88 min
Across delayed arrivals only, not all flights
Cancelled
1.47%
National rate is 1.81%
Whole route
74.0%
Every carrier on BUF to ORD, 2,196 flights
These figures cover 612 flights between July 2025 and June 2026. Beyond the headline rate, 9.6% 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
United against every carrier on BUF to ORD
United flew 612 of the 2,196 flights on BUF to ORD, about 28% of it. Its 74.1% on time is about level with the route as a whole at 74.0%. Ranked by on-time rate it is number three of five carriers on the route, where the range runs from American at 84.0% to SkyWest at 60.2%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. American Airlines arrives on time 84.0% of the time; Envoy Air manages 70.8%. Sample sizes sit next to every figure, because a two-point gap across 423 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| American Airlines | 476 | 84.0% | 124 min | 1.47% | B |
| Republic Airwaysthin sample | 355 | 76.2% | 95 min | 3.66% | B− |
| United Airlines (this page) | 612 | 74.1% | 88 min | 1.47% | C |
| Envoy Air | 423 | 70.8% | 68 min | 3.31% | C− |
| SkyWest Airlinesthin sample | 330 | 60.2% | 134 min | 6.06% | D− |
Envoy Air cancels 3.3% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 49 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am272 flights85.4%
- 8am–11am88 flights80.5%
- 11am–2pm83 flights92.8%
- 2pm–5pm1 flights—
- 5pm–8pm168 flights43.4%
- 8pm–5am—
Scale runs 35% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 43.4% on time, against 92.8% for the 11am–2pm 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 5am–8am window is the busiest, with 272 flights scheduled in it.
Across the year
United on BUF to ORD through the year
July is the worst month at 64.2% on time, 16 points below March, the best at 80.0%. 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. September was the busiest month here, with 89 flights.
Across the week, Thursday is the strongest day at 80.2% on time and Monday the weakest at 69.0%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 14,000 reported delay minutes.
- 39%National Airspace System
- 35%Carrier
- 21%Late-arriving aircraft
- 5%Extreme weather
39% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 5,432 minutes out of 14,000, against a national NAS share of 21%. The split is drawn from 13,783 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 4,870 of the 14,000 delay minutes reported here.
Cancellations sit at 1.47% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
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. 9.6% 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 11am–2pm window matters as much as it does.
The return leg runs 73.8% on time across 612 flights, within half a point 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. 612 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 United on BUF to ORD
Put together: treat all of this as provisional. 612 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 74.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 603 completed flights over 12 months sit behind that.
Related
Where to go next
- BUF to ORD, every carrier
- United on ORD to BUF, the return leg
- American Airlines on BUF to ORD84.0%
- Republic Airways on BUF to ORD76.2%
- Envoy Air on BUF to ORD70.8%
- SkyWest Airlines on BUF to ORD60.2%
- United Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Same route, different airline: where the carrier you pick matters most
- How often a connection fails at the major US hubs
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.