Carrier route record

WNBWI→ATL

Southwest Airlines · Baltimore to Atlanta

Flights: 1,573
Period: July 2025 to June 2026
Share of route: 29%
Carriers: 4

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

Southwest on BWI to ATL lands a B, level with the national rate of 77.6%. Roughly one flight in four arrives 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 1,573 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 2,824 at 86.2% on time.

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

On time

77.4%

Arrivals under 15 minutes late, of 1,547 completed flights

Avg delay

60 min

Across delayed arrivals only, not all flights

Cancelled

1.34%

National rate is 1.81%

Whole route

80.6%

Every carrier on BWI to ATL, 5,415 flights

These figures cover 1,573 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.

Carrier by carrier

Southwest against every carrier on BWI to ATL

Southwest flew 1,573 of the 5,415 flights on BWI to ATL, about 29% of it. Its 77.4% on time is 3 points worse than the route as a whole, which runs 80.6%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Delta at 86.2% to Frontier at 68.0%. 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 86.2% of the time; Frontier Airlines manages 68.0%. Sample sizes sit next to every figure, because a two-point gap across 883 flights means less than a ten-point one.

On-time performance by carrier on BWI to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	2,824	86.2%	79 min	2.05%	A
Spirit Airlinesthin sample	135	84.3%	67 min	0.74%	B+
Southwest Airlines (this page)	1,573	77.4%	60 min	1.34%	B
Frontier Airlines	883	68.0%	71 min	2.38%	C

The spread between Delta and Frontier is 18 points, wide enough that it should decide the booking. On a hundred trips that is 18 more arrivals inside the on-time window.

Departure window

When Southwest runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 41 points, against 18 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am95 flights92.5%
8am–11am490 flights91.1%
11am–2pm224 flights76.7%
2pm–5pm263 flights79.3%
5pm–8pm411 flights62.2%
8pm–5am90 flights51.7%

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

The 8pm–5am window is where this operation falls apart: 51.7% on time, against 92.5% 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 8am–11am window is the busiest, with 490 flights scheduled in it.

Across the year

Southwest on BWI to ATL through the year

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

Delays peak in March, when the on-time rate falls to 62.7%. February is the strongest month at 89.2%. Moving a flexible trip across that boundary buys 27 points. October was the busiest month here, with 148 flights.

Across the week, Tuesday is the strongest day at 87.4% on time and Thursday the weakest at 71.4%. 16 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 21,000 reported delay minutes.

Late-arriving aircraft
40%
Carrier
31%
National Airspace System
21%
Extreme weather
6%
Security
2%

40% 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 21,000 reported delay minutes here, that single category outweighs weather by 7 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 21,037 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 92.5% on time here.

Cancellations sit at 1.34% against a national 1.81%, which is ordinary. Diversions add another 0.32%.

Connections and stage length

What a delay here costs

7.0% 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 last about an hour, which a normal layover absorbs.

The 577 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 78.8% on time across 1,569 flights, within about a point 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 1,573 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 Southwest on BWI to ATL

Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 89.2% on time and March 62.7%, a swing of 27 points. If the dates move at all, move them out of March before you think about anything else. 1,547 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