Carrier route record

WNATL→SAT

Southwest Airlines · Atlanta to San Antonio

Flights: 318
Period: July 2025 to June 2026
Share of route: 11%
Carriers: 4

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

Southwest on ATL to SAT lands a B+, 4 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 50 minutes on average. That is a workable record, not a spotless one. That rests on 318 flights, with a median arrival 6 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Southwest on ATL to SAT from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

81.4%

Arrivals under 15 minutes late, of 317 completed flights

Avg delay

49 min

Across delayed arrivals only, not all flights

Cancelled

0.31%

National rate is 1.81%

Whole route

81.2%

Every carrier on ATL to SAT, 3,027 flights

These figures cover 318 flights between July 2025 and June 2026. The median arrival is 6 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 ATL to SAT

Southwest flew 318 of the 3,027 flights on ATL to SAT, about 11% of it. Its 81.4% on time is about level with the route as a whole at 81.2%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Spirit at 87.5% to Frontier at 71.4%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on ATL to SAT
Airline	Flights	On time	Avg delay	Cancelled	Grade
Spirit Airlinesthin sample	8	87.5%	15 min	0.00%	A+
Delta Air Lines	2,610	81.5%	53 min	1.69%	B
Southwest Airlines (this page)thin sample	318	81.4%	49 min	0.31%	B+
Frontier Airlinesthin sample	91	71.4%	94 min	0.00%	C+

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 318 flights.

5am–8am—
8am–11am13 flights—
11am–2pm55 flights76.4%
2pm–5pm242 flights83.0%
5pm–8pm8 flights—
8pm–5am—

Scale runs 70% to 90%. 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 76.4% on time against 83.0% for 2pm–5pm. 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 2pm–5pm window is the busiest, with 242 flights scheduled in it.

Across the year

Southwest on ATL to SAT through the year

Jul–Sep 202592 flights80.4%
Oct–Dec 202592 flights88.0%
Jan–Mar 202662 flights86.9%
Apr–Jun 202672 flights69.4%

Scale runs 60% to 95%. 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 81.4% on time across 318 flights.

Southwest on ATL to SAT did not run the same all year. Its best quarter was Oct–Dec 2025 at 88.0% on time and its weakest Apr–Jun 2026 at 69.4%, a swing of 19 points on roughly 80 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, Wednesday is the strongest day at 92.5% on time and Saturday the weakest at 70.0%. 23 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 66% of the 2,891 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
66%
Carrier
20%
National Airspace System
12%
Security
1%
Extreme weather
1%

66% 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 2,891 reported delay minutes here, that single category outweighs weather by 66 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 2,891 reported delay minutes.

Cancellations are rare at 0.31%, 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 4.7% 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.

The 874 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 79.9% on time across 318 flights, within 2 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. 318 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 ATL to SAT

Put together: treat all of this as provisional. 318 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 81.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 317 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