Carrier route record

WNDTW→LAS

Southwest Airlines · Detroit to Las Vegas

Flights: 337
Period: July 2025 to June 2026
Share of route: 12%
Carriers: 4

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on DTW 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, 7 points worse than the national rate of 77.6%. The late ones land roughly 40 minutes behind schedule. That rests on 337 flights. The strongest carrier on the route with a full sample, Spirit Airlines, flew 564 at 81.1% on time.

The national on-time rate over the same period is 77.6%, so Southwest on DTW to LAS runs 7 points behind the country as a whole. Across a thousand flights that is about 68 extra late arrivals.

On time

70.8%

Arrivals under 15 minutes late, of 336 completed flights

Avg delay

42 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

Whole route

76.1%

Every carrier on DTW to LAS, 2,843 flights

These figures cover 337 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.

Carrier by carrier

Southwest against every carrier on DTW to LAS

Southwest flew 337 of the 2,843 flights on DTW to LAS, about 12% of it. Its 70.8% on time is 5 points worse than the route as a whole, which runs 76.1%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Spirit at 81.1% to Frontier at 62.2%. One 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.

On-time performance by carrier on DTW to LAS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Spirit Airlines	564	81.1%	51 min	0.71%	B+
Delta Air Lines	1,897	75.9%	60 min	0.53%	B+
Southwest Airlines (this page)thin sample	337	70.8%	42 min	0.00%	C+
Frontier Airlinesthin sample	45	62.2%	62 min	0.00%	D+

No carrier stands out. Spirit tops the table at 81.1%, 5 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 27 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am53 flights90.6%
8am–11am83 flights78.3%
11am–2pm158 flights63.7%
2pm–5pm25 flights—
5pm–8pm18 flights—
8pm–5am—

Scale runs 55% to 95%. 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 63.7% on time against 90.6% for 5am–8am. 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 11am–2pm window is the busiest, with 158 flights scheduled in it.

Across the year

Southwest on DTW to LAS through the year

Jul–Sep 202566 flights84.8%
Oct–Dec 202590 flights74.2%
Jan–Mar 202690 flights75.6%
Apr–Jun 202691 flights52.7%

Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 70.8% on time across 337 flights.

Southwest on DTW to LAS did not run the same all year. Its best quarter was Jul–Sep 2025 at 84.8% on time and its weakest Apr–Jun 2026 at 52.7%, a swing of 32 points on roughly 84 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Thursday is the strongest day at 84.3% on time and Friday the weakest at 58.8%. 26 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 48% of the 4,149 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.

Late-arriving aircraft
48%
Carrier
30%
National Airspace System
19%
Extreme weather
1%
Security
1%

48% 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 4,149 reported delay minutes here, that single category outweighs weather by 40 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 4,149 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 90.6% on time here.

Cancellations are rare at 0.00%, below the national 1.81% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 4.5% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

At 1,749 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 68.0% on time across 337 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.

One caution: this is a thin sample. 337 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 DTW to LAS

Put together: treat all of this as provisional. 337 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 70.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 336 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures