Route reliability record

AUS→ATL

Austin to Atlanta

Flights: 4,544
Period: July 2025 to June 2026
Distance: 813 mi
Carriers: 4

This route lands a B, 4 points better than the national rate of 77.6%. About one flight in six arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 4,544 flights, of which Delta Air Lines flew 3,232 at 85.6% on time.

Set against the rest of the country, this route's record is 4 points better than the US average of 77.6%. That gap is worth roughly 44 fewer late arrivals for every thousand flights.

On time

82.0%

Arrivals under 15 minutes late, of 4,470 completed flights

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

1.43%

National rate is 1.81%

Best carrier

Delta

85.6% on time across 3,232 flights

These figures cover 4,544 flights between July 2025 and June 2026. The median arrival is 9 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 AUS to ATL

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 85.6% of the time; Southwest Airlines manages 78.8%. Sample sizes sit next to every figure, because a two-point gap across 1,036 flights means less than a ten-point one.

On-time performance by carrier on AUS to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlinesthin sample	1	100.0%	—	0.00%	A+
Delta Air Lines	3,232	85.6%	73 min	1.49%	A
Southwest Airlines	1,036	78.8%	53 min	0.68%	B+
Frontier Airlinesthin sample	275	52.1%	74 min	3.64%	F−

Delta leads Southwest by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

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 30 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am787 flights95.3%
8am–11am935 flights90.4%
11am–2pm951 flights84.9%
2pm–5pm816 flights73.2%
5pm–8pm1,017 flights69.0%
8pm–5am38 flights65.8%

Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 95.3% of the time, against 65.8% for the overnight window. That is 30 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 1,017 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 19 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.September best, July worst

July is the worst month at 71.9% on time, 19 points below September, the best at 90.6%. 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 412 flights.

Across the week, Tuesday is the strongest day at 87.1% on time and Sunday the weakest at 74.1%. 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. Late-arriving aircraft accounts for 46% of the 55,000 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.

Late-arriving aircraft
46%
Carrier
30%
National Airspace System
21%
Extreme weather
3%

46% 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 55,000 reported delay minutes here, that single category outweighs weather by 15 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 54,646 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 95.3% on time here.

Cancellations sit at 1.43% against a national 1.81%, which is ordinary. Diversions add another 0.20%.

Connections and stage length

What a delay here actually costs

5.8% 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 a little over an hour kind, which a normal layover absorbs.

The 813 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 79.8% on time across 4,545 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.

The sample behind these figures is 4,544 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. September runs 90.6% on time and July 71.9%, a swing of 19 points. If the dates move at all, move them out of July before you think about anything else. 4,470 completed flights over 12 months sit behind that.

Common questions

AUS to ATL questions

How often is AUS to ATL delayed?

About one flight in six arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.0% of the 4,544 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.

Which airline is most reliable on AUS to ATL?

Delta Air Lines leads at 85.6% on time across 3,232 flights. Southwest Airlines is at the other end on 78.8%, a gap of 7 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

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

The 5am–8am departure window is the strongest at 95.3% on time. The 8pm–5am window is the weakest at 65.8%, 30 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 AUS to ATL?

July is the weakest month at 71.9% on time, compared with 90.6% in September. Across the year that is 19 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. AUS to ATL and ATL to AUS 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