Carrier route record
WNLAS→ORD
Southwest Airlines · Las Vegas to Chicago
- Flights
- 669
- 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 LAS to ORD draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 669 flights. The strongest carrier on the route with a full sample, United Airlines, flew 2,330 at 79.3% on time.
The national on-time rate over the same period is 77.6%, so Southwest on LAS to ORD runs 11 points behind the country as a whole. Across a thousand flights that is about 110 extra late arrivals.
Key figures
On time
66.6%
Arrivals under 15 minutes late, of 658 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.30%
National rate is 1.81%
Whole route
76.5%
Every carrier on LAS to ORD, 5,297 flights
These figures cover 669 flights between July 2025 and June 2026. Beyond the headline rate, 9.7% 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 LAS to ORD
Southwest flew 669 of the 5,297 flights on LAS to ORD, about 13% of it. Its 66.6% on time is 10 points worse than the route as a whole, which runs 76.5%. Ranked by on-time rate it is last of five carriers on the route, where the range runs from Spirit at 83.6% to Southwest at 66.6%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two carriers here are closely matched: 3 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 | 266 | 83.6% | 54 min | 1.50% | B |
| United Airlines | 2,330 | 79.3% | 71 min | 0.43% | B+ |
| American Airlines | 1,848 | 76.2% | 99 min | 2.27% | B |
| Frontier Airlinesthin sample | 184 | 68.6% | 88 min | 4.35% | C− |
| Southwest Airlines (this page) | 669 | 66.6% | 58 min | 0.30% | C+ |
No carrier stands out. United tops the table at 79.3%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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 16 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1 flights—
- 8am–11am305 flights68.9%
- 11am–2pm37 flights52.9%
- 2pm–5pm—
- 5pm–8pm326 flights65.7%
- 8pm–5am—
Scale runs 45% to 75%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 52.9% on time against 68.9% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 5pm–8pm window is the busiest, with 326 flights scheduled in it.
Across the year
Southwest on LAS to ORD through the year
Delays peak in April, when the on-time rate falls to 54.8%. December is the strongest month at 77.4%. Moving a flexible trip across that boundary buys 23 points. May was the busiest month here, with 70 flights.
Across the week, Tuesday is the strongest day at 78.1% on time and Friday the weakest at 55.0%. 23 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
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 13,000 reported delay minutes.
- 39%Late-arriving aircraft
- 33%National Airspace System
- 25%Carrier
- 3%Extreme weather
39% 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 14 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 12,777 reported delay minutes.
33% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 4,241 minutes out of 13,000, against a national NAS share of 21%.
Cancellations are rare at 0.30%, 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. 9.7% 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 72.1% on time across 670 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.
One caution: this is a thin sample. 669 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 LAS to ORD
Put together: treat all of this as provisional. 669 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 66.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 658 completed flights over 12 months sit behind that.
Related
Where to go next
- LAS to ORD, every carrier
- Southwest on ORD to LAS, the return leg
- Spirit Airlines on LAS to ORD83.6%
- United Airlines on LAS to ORD79.3%
- American Airlines on LAS to ORD76.2%
- Frontier Airlines on LAS to ORD68.6%
- Southwest Airlines network-wide record
- Harry Reid International (LAS) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.