Carrier route record

AABOI→ORD

American Airlines · Boise to Chicago

Flights: 172
Period: July 2025 to June 2026
Share of route: 15%
Carriers: 4

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with American Airlines.

American on BOI to ORD draws a D+. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is an hour and a half behind schedule. Build slack into anything you connect to. That rests on 172 flights, with a median arrival 4 minutes late.

The national on-time rate over the same period is 77.6%, so American on BOI to ORD runs 16 points behind the country as a whole. Across a thousand flights that is about 162 extra late arrivals.

On time

61.4%

Arrivals under 15 minutes late, of 171 completed flights

Avg delay

88 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

Whole route

75.3%

Every carrier on BOI to ORD, 1,111 flights

These figures cover 172 flights between July 2025 and June 2026. Beyond the headline rate, 14.6% 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 BOI to ORD

American flew 172 of the 1,111 flights on BOI to ORD, about 15% of it. Its 61.4% on time is 14 points worse than the route as a whole, which runs 75.3%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from SkyWest at 83.6% to American at 61.4%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on BOI to ORD
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	507	83.6%	75 min	1.78%	B
United Airlinesthin sample	244	77.1%	85 min	0.82%	B+
Envoy Airthin sample	188	63.8%	99 min	0.00%	D+
American Airlines (this page)thin sample	172	61.4%	88 min	0.00%	D+

Departure window

When American runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 172 flights.

5am–8am—
8am–11am—
11am–2pm131 flights60.0%
2pm–5pm41 flights65.9%
5pm–8pm—
8pm–5am—

Scale runs 50% to 70%. Rows with fewer than 30 flights show a dash.

The weak window here is the middle of the day, not the evening: 11am–2pm runs 60.0% on time against 65.9% for 2pm–5pm. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 11am–2pm window is the busiest, with 131 flights scheduled in it.

Across the year

American on BOI to ORD through the year

Jul–Sep 202556 flights52.7%
Oct–Dec 202531 flights71.0%
Apr–Jun 202685 flights63.5%

Scale runs 45% to 75%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 61.4% on time across 172 flights.

American on BOI to ORD did not run the same all year. Its best quarter was Oct–Dec 2025 at 71.0% on time and its weakest Jul–Sep 2025 at 52.7%, a swing of 18 points on roughly 57 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Delay causes

Why American 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 5,790 reported delay minutes.

Late-arriving aircraft
37%
Carrier
33%
National Airspace System
16%
Extreme weather
14%

Extreme weather accounts for 14% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.3 times the usual weather exposure. The split is drawn from 5,790 reported delay minutes.

37% 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 5,790 reported delay minutes here, that single category outweighs weather by 3 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.

Cancellations are rare at 0.00%, below the national 1.81% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.

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. 14.6% 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 1,437 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 77.9% on time across 172 flights, 17 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 17 points of difference.

One caution: this is a thin sample. 172 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 American on BOI to ORD

Put together: treat all of this as provisional. 172 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 61.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 171 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures