Carrier route record
UAORD→BOI
United Airlines · Chicago to Boise
- Flights
- 245
- Period
- September 2025 to August 2026
- Share of route
- 22%
- Carriers
- 4
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on ORD to BOI lands a B+, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 245 flights, with a median arrival 6 minutes early.
The US average over the same twelve months is 77.3%, so there is little to separate United on ORD to BOI from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
77.4%
Arrivals under 15 minutes late, of 243 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.41%
National rate is 1.89%
Whole route
69.3%
Every carrier on ORD to BOI, 1,108 flights
These figures cover 245 flights between September 2025 and August 2026. Beyond the headline rate, 8.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
United against every carrier on ORD to BOI
United flew 245 of the 1,108 flights on ORD to BOI, about 22% of it. Its 77.4% on time is 8 points better than the route as a whole, which runs 69.3%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from American at 78.4% to Envoy at 62.9%. 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| American Airlinesthin sample | 208 | 78.4% | 62 min | 0.00% | B+ |
| United Airlines (this page)thin sample | 245 | 77.4% | 58 min | 0.41% | B+ |
| SkyWest Airlines | 503 | 63.4% | 82 min | 3.18% | D− |
| Envoy Airthin sample | 152 | 62.9% | 51 min | 0.00% | D+ |
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 United 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 245 flights.
- 5am–8am—
- 8am–11am194 flights81.2%
- 11am–2pm1 flights—
- 2pm–5pm33 flights75.8%
- 5pm–8pm—
- 8pm–5am17 flights—
Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.
The early departures do better, though not dramatically: 81.2% on time for the 8am–11am window against 75.8% for 2pm–5pm. Worth taking if the schedule allows, not worth an extra connection. The 8am–11am window is the busiest, with 194 flights scheduled in it.
Across the year
United on ORD to BOI through the year
- Jul–Sep 202536 flights86.1%
- Oct–Dec 202586 flights77.6%
- Apr–Jun 202661 flights70.0%
- Jul–Sep 202662 flights79.0%
Scale runs 60% to 90%.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 77.4% on time across 245 flights.
United on ORD to BOI did not run the same all year. Its best quarter was Jul–Sep 2025 at 86.1% on time and its weakest Apr–Jun 2026 at 70.0%, a swing of 16 points on roughly 61 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.
Across the week, Saturday is the strongest day at 83.3% on time and Wednesday the weakest at 69.7%, a spread of 14 points.
Arrival by arrival
How late United on ORD to BOI runs when it is late
United on ORD to BOI often beats the schedule: 75 of 243 completed flights, 31%, arrived 15 minutes or more early. The 55 late arrivals split 18 under half an hour, 17 between 30 and 60 minutes, and 20 an hour or more.
- 15+ min early75 flights30.9%
- Within 15 min113 flights46.5%
- 15–29 min late18 flights7.4%
- 30–59 min late17 flights7.0%
- 1–2 hours late16 flights6.6%
- 2+ hours late4 flights1.6%
Scale runs 0% to 100%.
Share of 243 completed flights by arrival against schedule.
6 of 46 late departures made up the time and arrived on time, 13% of them. In the other direction, 15 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 BOI.
The worst days
Worst days for United on ORD to BOI
The latest arrival of the period was on 13 August 2026, 3 hours 42 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on five of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 August 2026 | 3 hours 42 minutes | Late-arriving aircraft |
| 28 June 2026 | 3 hours 24 minutes | Late-arriving aircraft |
| 13 September 2025 | 3 hours 13 minutes | Late-arriving aircraft |
| 18 May 2026 | 2 hours 22 minutes | Late-arriving aircraft |
| 8 October 2025 | 1 hour 52 minutes | Late-arriving aircraft |
Delay causes
Why United runs late on this route
Late-arriving aircraft accounts for 44% of the 3,191 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Late-arriving aircraft
- 35%Carrier
- 20%National Airspace System
- 0%Extreme weather
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,191 reported delay minutes here, that single category outweighs weather by 44 to one. The split is drawn from 3,191 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,125 of the 3,191 delay minutes reported here.
Cancellations are rare at 0.41%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
8.2% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
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.
The return leg runs 75.5% on time across 244 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. 245 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 United on ORD to BOI
Put together: treat all of this as provisional. 245 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 77.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 243 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to BOI, every carrier
- United on BOI to ORD, the return leg
- American Airlines on ORD to BOI78.4%
- SkyWest Airlines on ORD to BOI63.4%
- Envoy Air on ORD to BOI62.9%
- United Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Why the first flight of the morning is statistically safest
- Connecting flights: how much buffer the data says you need
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.