Carrier route record
YXORD→BOS
Republic Airways · Chicago to Boston
- Flights
- 896
- Period
- July 2025 to June 2026
- Share of route
- 12%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Republic Airways.
Republic on ORD to BOS carries a cancellation problem, not just a delay problem: 5.5% of scheduled flights never operate, against 1.8% nationally. Of the ones that do fly, about seven flights in ten arrive on time, worth a C− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 896 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 444 at 82.8% on time.
Envoy Air is the most reliable of the five carriers covered here at 82.8% on time across 444 flights.
Key figures
On time
70.3%
Arrivals under 15 minutes late, of 846 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
5.47%
National rate is 1.81%
Whole route
67.6%
Every carrier on ORD to BOS, 7,642 flights
These figures cover 896 flights between July 2025 and June 2026. Beyond the headline rate, 11.7% 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 BOS
Republic flew 896 of the 7,642 flights on ORD to BOS, about 12% of it. Its 70.3% on time is 3 points better than the route as a whole, which runs 67.6%. Ranked by on-time rate it is number three of six carriers on the route, where the range runs from Envoy at 82.8% to American at 59.9%.
The choice of carrier is not cosmetic here. Envoy Air arrives on time 82.8% of the time; American Airlines manages 59.9%. Sample sizes sit next to every figure, because a two-point gap across 2,126 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 444 | 82.8% | 69 min | 2.48% | B |
| JetBlue Airways | 534 | 73.5% | 83 min | 2.62% | C |
| Republic Airways (this page) | 896 | 70.3% | 73 min | 5.47% | C− |
| Delta Air Lines | 962 | 69.1% | 88 min | 3.01% | C− |
| United Airlines | 2,680 | 68.6% | 78 min | 1.87% | C |
| American Airlines | 2,126 | 59.9% | 75 min | 2.82% | D |
Delta Air Lines cancels 3.0% 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 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 20 points, against 23 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am308 flights79.7%
- 8am–11am95 flights73.3%
- 11am–2pm100 flights68.0%
- 2pm–5pm163 flights62.3%
- 5pm–8pm130 flights64.7%
- 8pm–5am100 flights60.0%
Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 60.0% on time, against 79.7% 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 5am–8am window is the busiest, with 308 flights scheduled in it.
Across the year
Republic on ORD to BOS through the year
June is the worst month at 54.3% on time, 34 points below May, the best at 87.8%. 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. January was the busiest month here, with 178 flights.
Across the week, Thursday is the strongest day at 80.0% on time and Friday the weakest at 61.1%. 19 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Republic 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 18,000 reported delay minutes.
- 41%Late-arriving aircraft
- 26%National Airspace System
- 23%Carrier
- 10%Extreme weather
41% 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 18,000 reported delay minutes here, that single category outweighs weather by 4 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 18,255 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 79.7% on time here.
Cancellations run at 5.47%, against 1.81% nationally. That is roughly 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. 11.7% 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.
The 867 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 70.4% on time across 894 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. 896 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 BOS
Put together: the delay figures matter less here than the 5.47% 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. 846 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to BOS, every carrier
- Republic on BOS to ORD, the return leg
- Envoy Air on ORD to BOS82.8%
- JetBlue Airways on ORD to BOS73.5%
- Delta Air Lines on ORD to BOS69.1%
- United Airlines on ORD to BOS68.6%
- American Airlines on ORD to BOS59.9%
- Republic Airways network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Boston Logan International (BOS) delay statistics
- The US routes with the most cancellations
- Same route, different airline: where the carrier you pick matters most
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.