Route reliability record

ATL→SAT

Atlanta to San Antonio

Flights: 3,027
Period: July 2025 to June 2026
Distance: 874 mi
Carriers: 4

This route lands a B, 4 points better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by about 55 minutes on average. That is a workable record, not a spotless one. That rests on 3,027 flights, with a median arrival 7 minutes early.

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

On time

81.2%

Arrivals under 15 minutes late, of 2,978 completed flights

Avg delay

55 min

Across delayed arrivals only, not all flights

Cancelled

1.49%

National rate is 1.81%

Best carrier

Delta

81.5% on time across 2,610 flights

These figures cover 3,027 flights between July 2025 and June 2026. The median arrival is 7 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

Which airline is most reliable on ATL to SAT

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 Airlinesthin sample	318	81.4%	49 min	0.31%	B+
Frontier Airlinesthin sample	91	71.4%	94 min	0.00%	C+

Departure window

The best time of day to leave

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 14 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am662 flights88.4%
11am–2pm558 flights83.2%
2pm–5pm879 flights79.5%
5pm–8pm367 flights74.5%
8pm–5am561 flights77.9%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 88.4% of the time, against 74.5% for the evening window. That is 14 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 879 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 18 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

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

July is the worst month at 68.5% on time, 18 points below February, the best at 86.7%. 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. July was the busiest month here, with 277 flights.

Across the week, Wednesday is the strongest day at 88.4% on time and Sunday the weakest at 75.6%. 13 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

One category carries most of the weight here. Carrier accounts for 44% of the 31,000 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.

Carrier
44%
Late-arriving aircraft
34%
National Airspace System
17%
Extreme weather
4%
Security
0%

34% 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 31,000 reported delay minutes here, that single category outweighs weather by 8 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 30,617 reported delay minutes.

The largest share of delay minutes, 44%, 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 14,000 of the 31,000 delay minutes reported here.

Cancellations sit at 1.49% against a national 1.81%, which is ordinary. Diversions add another 0.13%.

Connections and stage length

What a delay here actually costs

5.4% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the about 55 minutes kind, which a normal layover absorbs.

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 is a different operation and performs like one: it runs 86.1% on time across 3,026 flights, 5 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 5 points of difference.

The sample behind these figures is 3,027 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 86.7% on time and July 68.5%, a swing of 18 points. If the dates move at all, move them out of July before you think about anything else. 2,978 completed flights over 12 months sit behind that.

Common questions

ATL to SAT questions

How often is ATL to SAT delayed?

About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.8% of the 3,027 flights in this analysis, against 22.4% nationally. Delayed flights are late by about 55 minutes on average.

How reliable is ATL to SAT compared with the rest of the country?

81.2% of flights arrive on time here against a national 77.6%, a difference of 4 points in its favour. That is worth a B on this site's grading scale.

What time of day has the fewest delays on ATL to SAT?

The 8am–11am departure window is the strongest at 88.4% on time. The 5pm–8pm window is the weakest at 74.5%, 14 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are July delays on ATL to SAT?

July is the weakest month at 68.5% on time, compared with 86.7% in February. Across the year that is 18 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. ATL to SAT and SAT to ATL are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures