Route reliability record
ORD→LAS
Chicago to Las Vegas
- Flights
- 5,154
- Period
- September 2025 to August 2026
- Distance
- 1,514 mi
- Carriers
- 5
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, 4 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 5,154 ORD to LAS flights, of which United Airlines flew 2,354 at 79.5% on time.
Best time to fly ORD to LAS: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 88.7% of the time and Tuesday flights 79.5%, against 72.9% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 79.5% on time across 2,354 flights.
Key figures
On time
72.9%
Arrivals under 15 minutes late, of 5,066 completed flights
Avg delay
75 min
Across delayed arrivals only, not all flights
Cancelled
1.34%
National rate is 1.89%
Best carrier
United
79.5% on time across 2,354 flights
These figures cover 5,154 flights between September 2025 and August 2026. Beyond the headline rate, 10.2% 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 LAS
The choice of carrier is not cosmetic here. United Airlines arrives on time 79.5% of the time; American Airlines manages 64.9%. Sample sizes sit next to every figure, because a two-point gap across 1,897 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 137 | 85.8% | 89 min | 2.19% | A |
| United Airlines | 2,354 | 79.5% | 68 min | 0.30% | B+ |
| Southwest Airlines | 551 | 73.4% | 67 min | 0.73% | C+ |
| American Airlines | 1,897 | 64.9% | 71 min | 2.16% | D |
| Frontier Airlinesthin sample | 215 | 60.7% | 156 min | 6.51% | D− |
The spread between United and American is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
Flight by flight
Flights on ORD to LAS
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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Best ways to make this trip
The most reliable ways to fly Chicago to Las Vegas
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 1 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. ORD → LASChicago to Las Vegas | United Airlines | 79.3% | 79.5% | 0.30% | 5am–8am, Sat | UA 574 07:11 |
| 2. MDW → LASChicago to Las Vegas | Southwest Airlines | 75.5% | 76.2% | 0.90% | 5am–8am, Sat (route) | — |
| 3. ORD → LASChicago to Las Vegas | Southwest Airlines | 72.9% | 73.4% | 0.73% | 5am–8am, Tue | — |
| 4. ORD → LASChicago to Las Vegas | American Airlines | 63.5% | 64.9% | 2.16% | 5am–8am, Tue | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 33 points, against 15 points between the best and worst carrier.
- 5am–8am1,046 flights88.7%
- 8am–11am913 flights79.4%
- 11am–2pm925 flights77.3%
- 2pm–5pm747 flights64.9%
- 5pm–8pm640 flights63.2%
- 8pm–5am883 flights56.0%
Scale runs 50% to 95%.
The 8pm–5am window is where this operation falls apart: 56.0% on time, against 88.7% 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 5am–8am window is the busiest, with 1,046 flights scheduled in it.
Explore
Filter ORD to LAS 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 LAS, the best departure window is 5am–8am at 88.7% on time and the worst is 8pm–5am at 56.0%, a wide gap of 32.7 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am88.7%
- 8–11am79.4%
- 11am–2pm77.3%
- 2–5pm64.9%
- 5–8pm63.2%
- 8pm–5am56.0%
best all US flightsScale 50% to 95%.
Across the year
When delays peak on this route
This route's year swings by 18 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.
Delays peak in April, when the on-time rate falls to 64.5%. February is the strongest month at 82.6%. Moving a flexible trip across that boundary buys 18 points. April was the busiest month here, with 508 flights.
Across the week, Tuesday is the strongest day at 79.5% on time and Sunday the weakest at 68.3%, a spread of 11 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 47% of the 102,000 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Late-arriving aircraft
- 27%Carrier
- 20%National Airspace System
- 6%Extreme weather
- 0%Security
47% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 102,000 reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 102,440 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 88.7% on time here.
Cancellations sit at 1.34% against a national 1.89%, which is ordinary. Diversions add another 0.37%.
Connections and stage length
What a delay here actually costs
10.2% 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.
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 75.6% on time across 5,148 flights, within 3 points 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 5,154 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 LAS 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. February runs 82.6% on time and April 64.5%, a swing of 18 points. If the dates move at all, move them out of April before you think about anything else. 5,066 completed flights over 12 months sit behind that.
Common questions
ORD to LAS questions
How often is ORD to LAS delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 27.1% of the 5,154 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on ORD to LAS?
United Airlines leads at 79.5% on time across 2,354 flights. American Airlines is at the other end on 64.9%, a gap of 15 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on ORD to LAS?
The 5am–8am departure window is the strongest at 88.7% on time. The 8pm–5am window is the weakest at 56.0%, 33 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 April delays on ORD to LAS?
April is the weakest month at 64.5% on time, compared with 82.6% in February. Across the year that is 18 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
- LAS to ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- Harry Reid International (LAS) delay statistics
- Spirit Airlines on ORD to LAS85.8%
- United Airlines on ORD to LAS79.5%
- Southwest Airlines on ORD to LAS73.4%
- American Airlines on ORD to LAS64.9%
- Frontier Airlines on ORD to LAS60.7%
- ORD to LGA, a related route66.6%
- LAX to LAS, a related route75.8%
- ORD to BOS, a related route66.6%
- Spirit Airlines on-time record85.8%
- United Airlines on-time record79.5%
- Southwest Airlines on-time record73.4%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. ORD to LAS and LAS 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.