Carrier route record

AAORD→BOS

American Airlines · Chicago to Boston

Flights: 2,164
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 ORD to BOS draws a D. Roughly one flight in two arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 2,164 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 440 at 82.7% on time.

Envoy Air is the most reliable of the five carriers covered here at 82.7% on time across 440 flights.

On time

59.5%

Arrivals under 15 minutes late, of 2,096 completed flights

Avg delay

78 min

Across delayed arrivals only, not all flights

Cancelled

2.91%

National rate is 1.89%

Whole route

66.6%

Every carrier on ORD to BOS, 7,864 flights

These figures cover 2,164 flights between September 2025 and August 2026. Beyond the headline rate, 19.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

Carrier by carrier

American against every carrier on ORD to BOS

American flew 2,164 of the 7,864 flights on ORD to BOS, about 28% of it. Its 59.5% on time is 7 points worse than the route as a whole, which runs 66.6%. Ranked by on-time rate it is last of six carriers on the route, where the range runs from Envoy at 82.7% to American at 59.5%.

The choice of carrier is not cosmetic here. Envoy Air arrives on time 82.7% of the time; Delta Air Lines manages 67.4%. 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 ORD to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Envoy Air	440	82.7%	67 min	2.50%	B
Republic Airways	932	69.7%	79 min	5.90%	C−
JetBlue Airways	553	68.1%	98 min	3.98%	C−
United Airlines	2,794	68.0%	80 min	1.79%	C
Delta Air Lines	981	67.4%	90 min	3.47%	C−
American Airlines (this page)	2,164	59.5%	78 min	2.91%	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.

Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

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 15 points between the best and worst carrier.

5am–8am286 flights88.0%
8am–11am263 flights70.8%
11am–2pm353 flights56.6%
2pm–5pm410 flights50.4%
5pm–8pm571 flights51.2%
8pm–5am281 flights52.5%

Scale runs 40% to 95%.

Book the early departure. Flights leaving between 5am–8am arrive on time 88.0% of the time, against 50.4% for the afternoon window. That is 38 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 571 flights scheduled in it.

Across the year

American on ORD to BOS through the year

Darker means more delays. Figures are on-time percentages.November best, March worst

November is the best month on the calendar at 72.7% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. May was the busiest month here, with 257 flights.

Across the week, Saturday is the strongest day at 67.0% on time and Sunday the weakest at 53.3%, a spread of 14 points.

Arrival by arrival

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

American on ORD to BOS often beats the schedule: 530 of 2,096 completed flights, 25%, arrived 15 minutes or more early. The 849 late arrivals split 210 under half an hour, 240 between 30 and 60 minutes, and 399 an hour or more.

15+ min early530 flights25.3%
Within 15 min717 flights34.2%
15–29 min late210 flights10.0%
30–59 min late240 flights11.5%
1–2 hours late257 flights12.3%
2+ hours late142 flights6.8%

Scale runs 0% to 100%.

Share of 2,096 completed flights by arrival against schedule.

126 of 870 late departures made up the time and arrived on time, 14% of them. In the other direction, 105 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 BOS.

The worst days

Worst days for American on ORD to BOS

The latest arrival of the period was on 23 February 2026, 17 hours 30 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. Three of the five worst days fell in February 2026.

The latest arrivals of American on ORD to BOS in the period
Date	Arrived late by	Largest filed cause
23 February 2026	17 hours 30 minutes	Late-arriving aircraft
23 February 2026	13 hours 14 minutes	Late-arriving aircraft
17 February 2026	11 hours 36 minutes	Late-arriving aircraft
31 March 2026	11 hours 17 minutes	Extreme weather
24 June 2026	10 hours 21 minutes	Carrier

Delay causes

Why American runs late on this route

Late-arriving aircraft accounts for 51% of the 67,000 delay minutes carriers reported here, and the remaining four split what is left.

Late-arriving aircraft
51%
National Airspace System
26%
Carrier
20%
Extreme weather
4%
Security
0%

51% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 67,000 reported delay minutes here, that single category outweighs weather by 14 to one. The split is drawn from 66,576 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 88.0% on time here.

Cancellations run at 2.91%, 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

19.0% 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 73.3% on time across 2,165 flights, 14 points above 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 2,164 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 ORD to BOS

Put together: the delay figures matter less here than the 2.91% 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. 2,096 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