Carrier route record
YXBOS→ORD
Republic Airways · Boston to Chicago
- Flights
- 894
- 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 BOS to ORD carries a cancellation problem, not just a delay problem: 5.9% 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 894 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 445 at 75.6% on time.
Envoy Air is the most reliable of the five carriers covered here at 75.6% on time across 445 flights.
Key figures
On time
70.4%
Arrivals under 15 minutes late, of 838 completed flights
Avg delay
81 min
Across delayed arrivals only, not all flights
Cancelled
5.93%
National rate is 1.81%
Whole route
72.7%
Every carrier on BOS to ORD, 7,637 flights
These figures cover 894 flights between July 2025 and June 2026. Beyond the headline rate, 13.1% 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 BOS to ORD
Republic flew 894 of the 7,637 flights on BOS to ORD, about 12% of it. Its 70.4% on time is 2 points worse than the route as a whole, which runs 72.7%. Ranked by on-time rate it is number five of six carriers on the route, where the range runs from Envoy at 75.6% to Delta at 65.2%.
The choice of carrier is not cosmetic here. Envoy Air arrives on time 75.6% of the time; Delta Air Lines manages 65.2%. Sample sizes sit next to every figure, because a two-point gap across 962 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 445 | 75.6% | 91 min | 3.60% | B− |
| United Airlines | 2,678 | 75.0% | 85 min | 1.90% | B |
| JetBlue Airways | 533 | 73.6% | 68 min | 2.25% | C |
| American Airlines | 2,125 | 73.4% | 93 min | 2.82% | C |
| Republic Airways (this page) | 894 | 70.4% | 81 min | 5.93% | C− |
| Delta Air Lines | 962 | 65.2% | 75 min | 3.12% | C− |
Envoy Air cancels 3.6% 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.
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 18 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am124 flights75.2%
- 8am–11am198 flights77.9%
- 11am–2pm215 flights71.4%
- 2pm–5pm198 flights65.2%
- 5pm–8pm98 flights59.8%
- 8pm–5am61 flights65.5%
Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 59.8% on time, against 77.9% 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 11am–2pm window is the busiest, with 215 flights scheduled in it.
Across the year
Republic on BOS to ORD through the year
December is the weak month at 58.0% on time, against 87.8% in May. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. January was the busiest month here, with 178 flights.
Across the week, Thursday is the strongest day at 78.9% on time and Monday the weakest at 67.0%. 12 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 20,000 reported delay minutes.
- 38%National Airspace System
- 31%Late-arriving aircraft
- 20%Carrier
- 11%Extreme weather
- 0%Security
38% 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 7,687 minutes out of 20,000, against a national NAS share of 21%. The split is drawn from 20,040 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 77.9% on time here.
Cancellations run at 5.93%, against 1.81% nationally. That is roughly one flight in fifteen 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. 13.1% 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 70.3% on time across 896 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. 894 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 BOS to ORD
Put together: the delay figures matter less here than the 5.93% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 8am–11am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 838 completed flights over 12 months sit behind that.
Related
Where to go next
- BOS to ORD, every carrier
- Republic on ORD to BOS, the return leg
- Envoy Air on BOS to ORD75.6%
- United Airlines on BOS to ORD75.0%
- JetBlue Airways on BOS to ORD73.6%
- American Airlines on BOS to ORD73.4%
- Delta Air Lines on BOS to ORD65.2%
- Republic Airways network-wide record
- Boston Logan International (BOS) delay statistics
- Chicago O'Hare International (ORD) 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.