Route reliability record
ORD→BOI
Chicago to Boise
- Flights
- 1,108
- Period
- September 2025 to August 2026
- Distance
- 1,437 mi
- Carriers
- 4
This route sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 1,108 ORD to BOI flights, with a median arrival 1 minute early.
Best time to fly ORD to BOI: a 11am–2pm departure, ideally on a Saturday. Flights in that window arrived on time 75.4% of the time and Saturday flights 73.7%, against 69.3% for the route overall.
The national on-time rate over the same period is 77.3%, so this route runs 8 points behind the country as a whole. Across a thousand flights that is about 80 extra late arrivals.
Key figures
On time
69.3%
Arrivals under 15 minutes late, of 1,085 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
1.53%
National rate is 1.89%
Best carrier
SkyWest
63.4% on time across 503 flights
These figures cover 1,108 flights between September 2025 and August 2026. Beyond the headline rate, 12.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on ORD to BOI
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 Airlinesthin 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+ |
Flight by flight
Flights on ORD to BOI
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 32 points, against half a point between the best and worst carrier.
- 5am–8am1 flights—
- 8am–11am617 flights73.6%
- 11am–2pm118 flights75.4%
- 2pm–5pm44 flights68.2%
- 5pm–8pm250 flights63.4%
- 8pm–5am78 flights43.2%
Scale runs 35% to 80%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 43.2% on time, against 75.4% for the 11am–2pm 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 8am–11am window is the busiest, with 617 flights scheduled in it.
Explore
Filter ORD to BOI by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On ORD to BOI, the best departure window is 11am–2pm at 75.4% on time and the worst is 8pm–5am at 43.2%, a wide gap of 32.2 points. All US flights leaving 11am–2pm ran 78.3%.
- 5–8am—
- 8–11am73.6%
- 11am–2pm75.4%
- 2–5pm68.2%
- 5–8pm63.4%
- 8pm–5am43.2%
best all US flightsScale 35% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 45 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
December is the weak month at 40.8% on time, against 85.6% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. December was the busiest month here, with 106 flights.
Across the week, Saturday is the strongest day at 73.7% on time and Friday the weakest at 61.3%, a spread of 12 points.
Delay causes
Why this route gets delayed
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 23,000 reported delay minutes.
- 36%Late-arriving aircraft
- 35%Carrier
- 22%National Airspace System
- 7%Extreme weather
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 23,000 reported delay minutes here, that single category outweighs weather by 5 to one. The split is drawn from 23,363 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 8,240 of the 23,000 delay minutes reported here.
Cancellations sit at 1.53% against a national 1.89%, which is ordinary. Diversions add another 0.54%.
Connections and stage length
What a delay here actually costs
12.4% 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 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 is a different operation and performs like one: it runs 74.9% on time across 1,111 flights, 6 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 6 points of difference.
The sample behind these figures is 1,108 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.
Work out the risk of missing a connection in BOI after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 85.6% on time and December 40.8%, a swing of 45 points. If the dates move at all, move them out of December before you think about anything else. 1,085 completed flights over 12 months sit behind that.
Common questions
ORD to BOI questions
How often is ORD to BOI delayed?
Roughly one flight in three arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 30.7% of the 1,108 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
How reliable is ORD to BOI compared with the rest of the country?
69.3% of flights arrive on time here against a national 77.3%, a difference of 8 points against it. That is worth a C on this site's grading scale.
What time of day has the fewest delays on ORD to BOI?
The 11am–2pm departure window is the strongest at 75.4% on time. The 8pm–5am window is the weakest at 43.2%, 32 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are December delays on ORD to BOI?
December is the weakest month at 40.8% on time, compared with 85.6% in September. Across the year that is 45 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- BOI to ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- American Airlines on ORD to BOI78.4%
- United Airlines on ORD to BOI77.4%
- SkyWest Airlines on ORD to BOI63.4%
- Envoy Air on ORD to BOI62.9%
- ORD to LGA, a related route66.6%
- SEA to BOI, a related route86.3%
- ORD to BOS, a related route66.6%
- American Airlines on-time record78.4%
- United Airlines on-time record77.4%
- SkyWest Airlines on-time record63.4%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. ORD to BOI and BOI to ORD are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.