Carrier route record

AABOS→ORD

American Airlines · Boston to Chicago

Flights: 2,165
Period: September 2025 to August 2026
Share of route: 28%
Carriers: 6

Historical statistics for September 2025 to August 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 77.3%. The late ones land an hour and a half behind schedule. That rests on 2,165 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.

On time

73.3%

Arrivals under 15 minutes late, of 2,086 completed flights

Avg delay

98 min

Across delayed arrivals only, not all flights

Cancelled

2.86%

National rate is 1.89%

Whole route

71.9%

Every carrier on BOS to ORD, 7,860 flights

These figures cover 2,165 flights between September 2025 and August 2026. Beyond the headline rate, 13.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Carrier by carrier

American against every carrier on BOS to ORD

American flew 2,165 of the 7,860 flights on BOS to ORD, about 28% of it. Its 73.3% on time is about level with the route as a whole at 71.9%. Ranked by on-time rate it is number three 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.

On-time performance by carrier on BOS to ORD
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 (this page)	2,165	73.3%	98 min	2.86%	C
Republic Airways	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−

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.

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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 37 points, against 12 points between the best and worst carrier.

5am–8am537 flights90.6%
8am–11am320 flights90.2%
11am–2pm364 flights78.3%
2pm–5pm301 flights59.7%
5pm–8pm634 flights53.4%
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: 53.4% on time, against 90.6% 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 634 flights scheduled in it.

Across the year

American on BOS to ORD through the year

Darker means more delays. Figures are on-time percentages.February best, October worst

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, Tuesday is the strongest day at 77.9% on time and Monday the weakest at 70.3%, a spread of 8 points.

Arrival by arrival

How late American on BOS to ORD runs when it is late

American on BOS to ORD often beats the schedule: 845 of 2,086 completed flights, 41%, arrived 15 minutes or more early. When American on BOS to ORD is late it tends to be very late: 285 of its 557 late arrivals were an hour or more behind, and 143 were two hours or more.

15+ min early845 flights40.5%
Within 15 min684 flights32.8%
15–29 min late137 flights6.6%
30–59 min late135 flights6.5%
1–2 hours late142 flights6.8%
2+ hours late143 flights6.9%

Scale runs 0% to 100%.

Share of 2,086 completed flights by arrival against schedule.

100 of 564 late departures made up the time and arrived on time, 18% of them. 93 flights left on time and still arrived late.

The worst days

Worst days for American on BOS to ORD

The latest arrival of the period was on 3 July 2026, 17 hours 14 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The five worst days are spread across July, April, September, June and December, with no single month standing out.

The latest arrivals of American on BOS to ORD in the period
Date	Arrived late by	Largest filed cause
3 July 2026	17 hours 14 minutes	National Airspace System
27 April 2026	13 hours 19 minutes	Carrier
30 September 2025	12 hours 43 minutes	Carrier
9 June 2026	10 hours 50 minutes	Late-arriving aircraft
30 December 2025	9 hours 51 minutes	Extreme weather

Delay causes

Why American runs late on this route

Late-arriving aircraft accounts for 50% of the 54,000 delay minutes carriers reported here, and the remaining four split what is left.

Late-arriving aircraft
50%
National Airspace System
28%
Carrier
20%
Extreme weather
2%
Security
0%

50% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 54,000 reported delay minutes here, that single category outweighs weather by 25 to one. The split is drawn from 54,296 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 90.6% on time here.

Cancellations run at 2.86%, against 1.89% nationally. That is roughly 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 costs

13.7% 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 is a different operation and performs like one: it runs 59.5% on time across 2,164 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 2,165 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 2.86% 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. 2,086 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures