Carrier route record
AABOS→ORD
American Airlines · Boston to Chicago
- Flights
- 2,125
- Period
- July 2025 to June 2026
- Share of route
- 28%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with American Airlines.
American on BOS 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 2,125 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
73.4%
Arrivals under 15 minutes late, of 2,050 completed flights
Avg delay
93 min
Across delayed arrivals only, not all flights
Cancelled
2.82%
National rate is 1.81%
Whole route
72.7%
Every carrier on BOS to ORD, 7,637 flights
These figures cover 2,125 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
American against every carrier on BOS to ORD
American flew 2,125 of the 7,637 flights on BOS to ORD, about 28% of it. Its 73.4% on time is about level with the route as a whole at 72.7%. Ranked by on-time rate it is number four 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 (this page) | 2,125 | 73.4% | 93 min | 2.82% | C |
| Republic Airways | 894 | 70.4% | 81 min | 5.93% | C− |
| Delta Air Lines | 962 | 65.2% | 75 min | 3.12% | C− |
Republic Airways cancels 5.9% 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 American runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 38 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am532 flights90.9%
- 8am–11am262 flights90.8%
- 11am–2pm410 flights78.5%
- 2pm–5pm301 flights61.0%
- 5pm–8pm611 flights52.8%
- 8pm–5am9 flights—
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 52.8% on time, against 90.9% 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 5pm–8pm window is the busiest, with 611 flights scheduled in it.
Across the year
American on BOS to ORD through the year
Delays peak in October, when the on-time rate falls to 62.7%. February is the strongest month at 83.7%. Moving a flexible trip across that boundary buys 21 points. May was the busiest month here, with 256 flights.
Across the week, Wednesday is the strongest day at 79.9% on time and Thursday the weakest at 69.3%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why American runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 52% of the 51,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 52%Late-arriving aircraft
- 26%National Airspace System
- 20%Carrier
- 2%Extreme weather
- 0%Security
52% 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 51,000 reported delay minutes here, that single category outweighs weather by 26 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 50,535 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 90.9% on time here.
Cancellations run at 2.82%, against 1.81% nationally. That is roughly one flight in 40 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 is a different operation and performs like one: it runs 59.9% on time across 2,126 flights, 14 points below 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 14 points of difference.
The sample behind these figures is 2,125 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.
What to do with this
Booking American on BOS to ORD
Put together: the delay figures matter less here than the 2.82% cancellation rate. A late arrival costs you an hour and a half; 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. 2,050 completed flights over 12 months sit behind that.
Related
Where to go next
- BOS to ORD, every carrier
- American 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%
- Republic Airways on BOS to ORD70.4%
- Delta Air Lines on BOS to ORD65.2%
- American Airlines 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.