Route reliability record
ORD→BUF
Chicago to Buffalo
- Flights
- 2,204
- Period
- September 2025 to August 2026
- Distance
- 474 mi
- Carriers
- 5
This route sits in the middle of the pack with a C−. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 2,204 ORD to BUF flights, of which United Airlines flew 588 at 75.7% on time.
Best time to fly ORD to BUF: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 87.4% of the time and Saturday flights 75.5%, against 70.4% for the route overall.
United Airlines is the most reliable of the four carriers covered here at 75.7% on time across 588 flights.
Key figures
On time
70.4%
Arrivals under 15 minutes late, of 2,128 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
3.18%
National rate is 1.89%
Best carrier
United
75.7% on time across 588 flights
These figures cover 2,204 flights between September 2025 and August 2026. Beyond the headline rate, 12.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on ORD to BUF
The choice of carrier is not cosmetic here. United Airlines arrives on time 75.7% of the time; American Airlines manages 59.1%. Sample sizes sit next to every figure, because a two-point gap across 478 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 320 | 79.4% | 61 min | 2.81% | B |
| United Airlines | 588 | 75.7% | 79 min | 1.02% | B |
| Republic Airways | 428 | 74.4% | 71 min | 4.67% | C− |
| SkyWest Airlines | 390 | 64.3% | 81 min | 5.64% | D− |
| American Airlines | 478 | 59.1% | 89 min | 2.72% | D |
SkyWest Airlines cancels 5.6% 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.
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Best ways to make this trip
The most reliable ways to fly Chicago to Buffalo
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 3 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. ORD → ROCChicago to Rochester | Republic Airways | 78.3% | 79.9% | 1.97% | 5am–8am, Tue | — |
| 2. ORD → ROCChicago to Rochester | Envoy Air | 76.9% | 78.9% | 2.48% | 11am–2pm, Tue | — |
| 3. ORD → BUFChicago to Buffalo | United Airlines | 74.9% | 75.7% | 1.02% | 5am–8am, Tue | — |
| 4. MDW → BUFChicago to Buffalo | Southwest Airlines | 73.3% | 74.4% | 1.45% | 5am–8am, Tue | — |
| 5. ORD → BUFChicago to Buffalo | Republic Airways | 70.9% | 74.4% | 4.67% | 5am–8am, Sat | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 39 points, against 17 points between the best and worst carrier.
- 5am–8am379 flights87.4%
- 8am–11am267 flights76.4%
- 11am–2pm213 flights73.8%
- 2pm–5pm558 flights73.6%
- 5pm–8pm466 flights62.6%
- 8pm–5am321 flights48.0%
Scale runs 40% to 95%.
The 8pm–5am window is where this operation falls apart: 48.0% on time, against 87.4% 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 558 flights scheduled in it.
Explore
Filter ORD to BUF by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On ORD to BUF, the best departure window is 5am–8am at 87.4% on time and the worst is 8pm–5am at 48.0%, a wide gap of 39.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am87.4%
- 8–11am76.4%
- 11am–2pm73.8%
- 2–5pm73.6%
- 5–8pm62.6%
- 8pm–5am48.0%
best all US flightsScale 40% to 95%.
Across the year
When delays peak on this route
This route's year swings by 15 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
September is the best month on the calendar at 78.1% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. May was the busiest month here, with 217 flights.
Across the week, Saturday is the strongest day at 75.5% on time and Sunday the weakest at 60.4%, a spread of 15 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 50% of the 50,000 delay minutes carriers reported here, and the remaining four split what is left.
- 50%Late-arriving aircraft
- 26%Carrier
- 17%National Airspace System
- 8%Extreme weather
50% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 50,000 reported delay minutes here, that single category outweighs weather by 6 to one. The split is drawn from 49,990 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 87.4% on time here.
Cancellations run at 3.18%, against 1.89% nationally. That is about one flight in 30 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 actually costs
12.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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 is a different operation and performs like one: it runs 74.4% on time across 2,205 flights, 4 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 4 points of difference.
The sample behind these figures is 2,204 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in BUF after this flight
What to do with this
Booking this route
Put together: the delay figures matter less here than the 3.18% 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. 2,128 completed flights over 12 months sit behind that.
Common questions
ORD to BUF questions
How often is ORD to BUF delayed?
Roughly one flight in three arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 29.6% of the 2,204 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on ORD to BUF?
United Airlines leads at 75.7% on time across 588 flights. American Airlines is at the other end on 59.1%, a gap of 17 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on ORD to BUF?
The 5am–8am departure window is the strongest at 87.4% on time. The 8pm–5am window is the weakest at 48.0%, 39 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are March delays on ORD to BUF?
March is the weakest month at 62.6% on time, compared with 78.1% in September. Across the year that is 15 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- BUF to ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- Envoy Air on ORD to BUF79.4%
- United Airlines on ORD to BUF75.7%
- Republic Airways on ORD to BUF74.4%
- SkyWest Airlines on ORD to BUF64.3%
- American Airlines on ORD to BUF59.1%
- ORD to LGA, a related route66.6%
- MCO to BUF, a related route66.4%
- ORD to BOS, a related route66.6%
- Envoy Air on-time record79.4%
- United Airlines on-time record75.7%
- Republic Airways on-time record74.4%
- The US routes with the most cancellations
- Same route, different airline: where the carrier you pick matters most
Direction matters. ORD to BUF and BUF to ORD are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.