Carrier performance at one airport

WN→ATL

Southwest Airlines at Hartsfield-Jackson Atlanta International

Departures: 17,795
Period: July 2025 to June 2026
Routes: 21
Rank here: #5 of 12

Southwest Airlines at Atlanta lands a B, level with the national rate of 77.6%. Roughly one flight in four arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 17,795 flights, of which United Airlines flew 7,532 at 80.3% on time.

Measured against the airport rather than the country, Southwest Airlines runs about a point behind the 78.4% weighted average across all carriers at ATL. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.

On time

77.1%

17,530 completed departures

Avg delay

58 min

Across delayed flights only

Cancelled

1.15%

At ATL, this carrier only

Rank here

Of 12 carriers clearing the floor at ATL

These figures cover 18,000 flights between July 2025 and June 2026. The median arrival is 4 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.

Against the competition

Every carrier at ATL, ranked

The choice of carrier is not cosmetic here. United Airlines arrives on time 80.3% of the time; Frontier Airlines manages 64.5%. Sample sizes sit next to every figure, because a two-point gap across 19,734 flights means less than a ten-point one.

On-time performance of all carriers departing ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	7,532	80.3%	83 min	1.47%	B
Delta Air Lines	240,801	80.0%	59 min	1.60%	B
PSA Airlines	3,218	79.4%	109 min	4.72%	B−
Alaska Airlines	1,433	77.1%	56 min	0.77%	B+
Southwest Airlines (this page)	17,795	77.1%	58 min	1.15%	B
Republic Airways	2,880	77.0%	78 min	4.24%	B−
American Airlines	6,810	76.4%	102 min	2.10%	B
SkyWest Airlines	7,222	74.7%	106 min	2.26%	C
Envoy Air	1,112	73.2%	69 min	2.61%	C
Spirit Airlines	5,230	71.5%	75 min	3.14%	C−
JetBlue Airways	2,575	70.7%	89 min	3.30%	C−
Frontier Airlines	19,734	64.5%	82 min	2.15%	D

PSA Airlines cancels 4.7% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.

Route by route

Where Southwest Airlines flies from ATL

Southwest Airlines operates 21 routes out of ATL with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.

Southwest Airlines routes from ATL
Route	Flights	On time	Avg delay	Cancelled	Grade
ATL to BWI · Baltimore	1,569	78.8%	63 min	2.10%	B
ATL to DAL · Dallas	1,548	77.6%	58 min	1.68%	B
ATL to MDW · Chicago	1,545	75.9%	55 min	1.62%	B
ATL to HOU · Houston	1,499	79.9%	58 min	0.67%	B+
ATL to DCA · Washington	1,139	73.5%	66 min	1.76%	C
ATL to STL · St. Louis	1,130	79.9%	56 min	0.53%	B+
ATL to MCO · Orlando	1,095	75.4%	61 min	1.10%	B
ATL to DEN · Denver	1,079	73.4%	54 min	1.11%	C
ATL to AUS · Austin	1,036	81.9%	49 min	0.58%	B+
ATL to LGA · New York	935	69.6%	68 min	3.10%	C−
ATL to BNA · Nashville	881	79.1%	65 min	0.45%	B+
ATL to TPA · Tampa	732	75.9%	68 min	0.82%	B+
ATL to LAS · Las Vegas	719	77.2%	48 min	0.42%	B+
ATL to PHX · Phoenix	633	72.0%	48 min	0.32%	C+
ATL to MCI · Kansas City	365	75.9%	50 min	0.00%	B+
ATL to MSY · New Orleansthin sample	363	78.1%	46 min	0.28%	B+
ATL to IND · Indianapolisthin sample	330	79.5%	53 min	0.61%	B+
ATL to CMH · Columbusthin sample	326	76.5%	49 min	0.61%	B+
ATL to SAT · San Antoniothin sample	318	81.4%	49 min	0.31%	B+
ATL to PIT · Pittsburghthin sample	302	81.7%	55 min	0.33%	B+
ATL to RDU · Raleighthin sample	247	83.6%	63 min	1.21%	B

Departure window

Best time of day for this operation

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 39 points, against 16 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am2,643 flights93.3%
8am–11am2,384 flights87.3%
11am–2pm3,546 flights84.6%
2pm–5pm4,141 flights74.3%
5pm–8pm3,876 flights62.8%
8pm–5am1,205 flights54.5%

Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 54.5% on time, against 93.3% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 2pm–5pm window is the busiest, with 4,141 flights scheduled in it.

Across the year

Seasonal pattern

Darker means more delays. Figures are on-time percentages.January best, May worst

Delays peak in May, when the on-time rate falls to 66.4%. January is the strongest month at 88.4%. Moving a flexible trip across that boundary buys 22 points. July was the busiest month here, with 1,669 flights.

Delay causes

What holds this operation up

Late-arriving aircraft
48%
Carrier
27%
National Airspace System
20%
Extreme weather
4%
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 232,000 reported delay minutes here, that single category outweighs weather by 13 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 231,773 reported delay minutes.

Cancellations sit at 1.15% against a national 1.81%, which is ordinary. Diversions add another 0.34%.

6.9% 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 an hour kind, which a normal layover absorbs.

17,795 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 88.4% on time and May 66.4%, a swing of 22 points. If the dates move at all, move them out of May before you think about anything else. 17,530 completed flights over 12 months sit behind that.

Common questions

Southwest Airlines at ATL

How often is Southwest Airlines at ATL delayed?

Roughly one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.9% of the 17,795 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on Southwest Airlines at ATL?

United Airlines leads at 80.3% on time across 7,532 flights. Frontier Airlines is at the other end on 64.5%, a gap of 16 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 Southwest Airlines at ATL?

The 5am–8am departure window is the strongest at 93.3% on time. The 8pm–5am window is the weakest at 54.5%, 39 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 May delays on Southwest Airlines at ATL?

May is the weakest month at 66.4% on time, compared with 88.4% in January. Across the year that is 22 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

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