Carrier route record

WNLAS→ATL

Southwest Airlines · Las Vegas to Atlanta

Flights: 720
Period: July 2025 to June 2026
Share of route: 15%
Carriers: 4

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

Southwest on LAS to ATL lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about 40 minutes on average. That is a workable record, not a spotless one. That rests on 720 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 3,327 at 87.7% on time.

Set against the rest of the country, Southwest's LAS to ATL record is 5 points better than the US average of 77.6%. That gap is worth roughly 53 fewer late arrivals for every thousand flights.

On time

82.9%

Arrivals under 15 minutes late, of 713 completed flights

Avg delay

39 min

Across delayed arrivals only, not all flights

Cancelled

0.69%

National rate is 1.81%

Whole route

85.2%

Every carrier on LAS to ATL, 4,791 flights

These figures cover 720 flights between July 2025 and June 2026. The median arrival is 5 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

Southwest against every carrier on LAS to ATL

Southwest flew 720 of the 4,791 flights on LAS to ATL, about 15% of it. Its 82.9% on time is 2 points worse than the route as a whole, which runs 85.2%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from Delta at 87.7% to Frontier at 74.5%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 87.7% of the time; Frontier Airlines manages 74.5%. Sample sizes sit next to every figure, because a two-point gap across 561 flights means less than a ten-point one.

On-time performance by carrier on LAS to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	3,327	87.7%	83 min	0.72%	A+
Southwest Airlines (this page)	720	82.9%	39 min	0.69%	B+
Spirit Airlinesthin sample	183	82.3%	69 min	0.55%	B+
Frontier Airlines	561	74.5%	70 min	2.14%	C

The spread between Delta and Frontier 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 is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 720 flights.

5am–8am61 flights79.7%
8am–11am265 flights84.5%
11am–2pm28 flights—
2pm–5pm1 flights—
5pm–8pm—
8pm–5am365 flights86.4%

Scale runs 70% to 90%. Rows with fewer than 30 flights show a dash.

The overnight block holds up unusually well at 86.4% on time across 365 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8pm–5am window is the busiest, with 365 flights scheduled in it.

Across the year

Southwest on LAS to ATL through the year

Darker means more delays. Figures are on-time percentages.September best, July worst

July is the worst month at 73.8% on time, 21 points below September, the best at 95.1%. 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. March was the busiest month here, with 62 flights.

Across the week, Tuesday is the strongest day at 89.6% on time and Friday the weakest at 77.0%. 13 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 44% of the 4,767 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
44%
Carrier
41%
National Airspace System
15%

44% 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 4,767 reported delay minutes here, that single category outweighs weather by 44 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 4,767 reported delay minutes.

The largest share of delay minutes, 41%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 1,957 of the 4,767 delay minutes reported here.

Cancellations are rare at 0.69%, 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

Badly late arrivals are rare here: only 2.4% 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 1,747 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 77.2% on time across 719 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. 720 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 ATL

Put together: treat all of this as provisional. 720 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 82.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 713 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