Carrier route record
YXBOS→ORD
Republic Airways · Boston to Chicago
- Flights
- 930
- Period
- September 2025 to August 2026
- Share of route
- 12%
- Carriers
- 6
Historical statistics for September 2025 to August 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 1.9% 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 930 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 441 at 75.7% on time.
Envoy Air is the most reliable of the five carriers covered here at 75.7% on time across 441 flights.
Key figures
On time
71.2%
Arrivals under 15 minutes late, of 871 completed flights
Avg delay
82 min
Across delayed arrivals only, not all flights
Cancelled
5.91%
National rate is 1.89%
Whole route
71.9%
Every carrier on BOS to ORD, 7,860 flights
These figures cover 930 flights between September 2025 and August 2026. Beyond the headline rate, 13.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Republic against every carrier on BOS to ORD
Republic flew 930 of the 7,860 flights on BOS to ORD, about 12% of it. Its 71.2% on time is about level with the route as a whole at 71.9%. Ranked by on-time rate it is number four of six carriers on the route, where the range runs from Envoy at 75.7% to Delta at 63.7%.
The choice of carrier is not cosmetic here. Envoy Air arrives on time 75.7% of the time; Delta Air Lines manages 63.7%. Sample sizes sit next to every figure, because a two-point gap across 981 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 441 | 75.7% | 112 min | 3.40% | B− |
| United Airlines | 2,791 | 74.5% | 86 min | 1.79% | C |
| American Airlines | 2,165 | 73.3% | 98 min | 2.86% | C |
| Republic Airways (this page) | 930 | 71.2% | 82 min | 5.91% | C− |
| JetBlue Airways | 552 | 66.6% | 80 min | 3.26% | C− |
| Delta Air Lines | 981 | 63.7% | 75 min | 3.47% | D− |
Delta Air Lines cancels 3.5% 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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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 16 points, against 12 points between the best and worst carrier.
- 5am–8am117 flights73.6%
- 8am–11am198 flights77.9%
- 11am–2pm277 flights73.1%
- 2pm–5pm192 flights65.7%
- 5pm–8pm85 flights61.7%
- 8pm–5am61 flights65.5%
Scale runs 55% to 85%.
The 5pm–8pm window is where this operation falls apart: 61.7% 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 277 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 78.0% on time and Sunday the weakest at 65.1%, a spread of 13 points.
Arrival by arrival
How late Republic on BOS to ORD runs when it is late
Republic on BOS to ORD often beats the schedule: 283 of 871 completed flights, 32%, arrived 15 minutes or more early. The 251 late arrivals split 62 under half an hour, 75 between 30 and 60 minutes, and 114 an hour or more.
- 15+ min early283 flights32.5%
- Within 15 min337 flights38.7%
- 15–29 min late62 flights7.1%
- 30–59 min late75 flights8.6%
- 1–2 hours late70 flights8.0%
- 2+ hours late44 flights5.1%
Scale runs 0% to 100%.
Share of 871 completed flights by arrival against schedule.
43 of 220 late departures made up the time and arrived on time, 20% of them. In the other direction, 74 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at ORD.
The worst days
Worst days for Republic on BOS to ORD
The latest arrival of the period was on 11 June 2026, 20 hours 48 minutes behind schedule; most of its delay minutes were filed as extreme weather. Three of the five worst days fell in March 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 11 June 2026 | 20 hours 48 minutes | Extreme weather |
| 26 March 2026 | 11 hours 34 minutes | National Airspace System |
| 29 December 2025 | 10 hours 6 minutes | National Airspace System |
| 24 March 2026 | 5 hours 44 minutes | Late-arriving aircraft |
| 6 March 2026 | 5 hours 31 minutes | National Airspace System |
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 21,000 reported delay minutes.
- 40%National Airspace System
- 30%Late-arriving aircraft
- 19%Carrier
- 11%Extreme weather
- 0%Security
40% 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 8,251 minutes out of 21,000, against a national NAS share of 21%. The split is drawn from 20,519 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 5.91%, against 1.89% 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
13.1% 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.
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.
The return leg runs 69.7% on time across 932 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. 930 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 5.91% 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. 871 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 ORD75.7%
- United Airlines on BOS to ORD74.5%
- American Airlines on BOS to ORD73.3%
- JetBlue Airways on BOS to ORD66.6%
- Delta Air Lines on BOS to ORD63.7%
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.