Carrier route record
UAORD→LAS
United Airlines · Chicago to Las Vegas
- Flights
- 2,328
- Period
- July 2025 to June 2026
- Share of route
- 44%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on ORD to LAS lands a B+, 2 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 2,328 flights. The strongest carrier on the route with a full sample, Southwest Airlines, flew 670 at 72.1% on time.
The US average over the same twelve months is 77.6%, so there is little to separate United on ORD to LAS from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.6%
Arrivals under 15 minutes late, of 2,313 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.43%
National rate is 1.81%
Whole route
73.7%
Every carrier on ORD to LAS, 5,297 flights
These figures cover 2,328 flights between July 2025 and June 2026. The median arrival is 6 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
United against every carrier on ORD to LAS
United flew 2,328 of the 5,297 flights on ORD to LAS, about 44% of it. Its 79.6% on time is 6 points better than the route as a whole, which runs 73.7%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from Spirit at 83.7% to Frontier at 58.3%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 261 | 83.7% | 73 min | 1.15% | B |
| United Airlines (this page) | 2,328 | 79.6% | 64 min | 0.43% | B+ |
| Southwest Airlines | 670 | 72.1% | 69 min | 0.75% | C+ |
| American Airlines | 1,852 | 66.8% | 71 min | 2.21% | C |
| Frontier Airlinesthin sample | 186 | 58.3% | 124 min | 5.91% | D− |
No carrier stands out. Southwest tops the table at 72.1%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
United flight numbers on ORD to LAS
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 36 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am371 flights95.4%
- 8am–11am559 flights81.5%
- 11am–2pm590 flights83.7%
- 2pm–5pm417 flights71.8%
- 5pm–8pm176 flights68.0%
- 8pm–5am215 flights59.7%
Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 59.7% on time, against 95.4% 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 11am–2pm window is the busiest, with 590 flights scheduled in it.
Across the year
United on ORD to LAS through the year
July is the worst month at 70.1% on time, 20 points below February, the best at 90.5%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. May was the busiest month here, with 220 flights.
Across the week, Tuesday is the strongest day at 83.8% on time and Monday the weakest at 74.4%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 43% of the 30,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 43%Late-arriving aircraft
- 27%National Airspace System
- 23%Carrier
- 7%Extreme weather
43% 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 30,000 reported delay minutes here, that single category outweighs weather by 6 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. The split is drawn from 30,414 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 95.4% on time here.
Cancellations are rare at 0.43%, below the national 1.81% 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
6.9% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says 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.
At 1,514 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg runs 79.3% on time across 2,330 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 2,328 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 United on ORD to LAS
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 90.5% on time and July 70.1%, a swing of 20 points. If the dates move at all, move them out of July before you think about anything else. 2,313 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to LAS, every carrier
- United on LAS to ORD, the return leg
- Spirit Airlines on ORD to LAS83.7%
- Southwest Airlines on ORD to LAS72.1%
- American Airlines on ORD to LAS66.8%
- Frontier Airlines on ORD to LAS58.3%
- United Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Harry Reid International (LAS) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.