Carrier route record
WNORD→LAS
Southwest Airlines · Chicago to Las Vegas
- Flights
- 670
- Period
- July 2025 to June 2026
- Share of route
- 13%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on ORD to LAS sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 670 flights. The strongest carrier on the route with a full sample, United Airlines, flew 2,328 at 79.6% on time.
The national on-time rate over the same period is 77.6%, so Southwest on ORD to LAS runs 6 points behind the country as a whole. Across a thousand flights that is about 55 extra late arrivals.
Key figures
On time
72.1%
Arrivals under 15 minutes late, of 663 completed flights
Avg delay
69 min
Across delayed arrivals only, not all flights
Cancelled
0.75%
National rate is 1.81%
Whole route
73.7%
Every carrier on ORD to LAS, 5,297 flights
These figures cover 670 flights between July 2025 and June 2026. Beyond the headline rate, 10.7% 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
Southwest against every carrier on ORD to LAS
Southwest flew 670 of the 5,297 flights on ORD to LAS, about 13% of it. Its 72.1% on time is 2 points worse than the route as a whole, which runs 73.7%. Ranked by on-time rate it is number three 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 choice of carrier is not cosmetic here. United Airlines arrives on time 79.6% of the time; American Airlines manages 66.8%. Sample sizes sit next to every figure, because a two-point gap across 1,852 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 261 | 83.7% | 73 min | 1.15% | B |
| United Airlines | 2,328 | 79.6% | 64 min | 0.43% | B+ |
| Southwest Airlines (this page) | 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− |
The spread between United and American is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 more arrivals inside the on-time window.
Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 49 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am328 flights88.4%
- 8am–11am2 flights—
- 11am–2pm116 flights70.2%
- 2pm–5pm67 flights39.4%
- 5pm–8pm157 flights52.6%
- 8pm–5am—
Scale runs 30% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 88.4% of the time, against 39.4% for the afternoon window. That is 49 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 328 flights scheduled in it.
Across the year
Southwest on ORD to LAS through the year
July is the worst month at 59.0% on time, 31 points below October, the best at 89.5%. 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 70 flights.
Across the week, Tuesday is the strongest day at 79.4% on time and Sunday the weakest at 65.1%. 14 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 50% of the 13,000 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.
- 50%Late-arriving aircraft
- 26%Carrier
- 22%National Airspace System
- 1%Security
- 1%Extreme weather
50% 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 13,000 reported delay minutes here, that single category outweighs weather by 46 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 12,724 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 88.4% on time here.
Cancellations are rare at 0.75%, 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
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.7% 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.
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 is a different operation and performs like one: it runs 66.6% on time across 669 flights, 6 points below 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.
One caution: this is a thin sample. 670 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 Southwest on ORD to LAS
Put together: treat all of this as provisional. 670 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 72.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 663 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to LAS, every carrier
- Southwest on LAS to ORD, the return leg
- Spirit Airlines on ORD to LAS83.7%
- United Airlines on ORD to LAS79.6%
- American Airlines on ORD to LAS66.8%
- Frontier Airlines on ORD to LAS58.3%
- Southwest Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Harry Reid International (LAS) delay statistics
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
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.