Carrier route record
WNMKE→DCA
Southwest Airlines · Milwaukee to Washington
- Flights
- 680
- Period
- September 2025 to August 2026
- Share of route
- 51%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on MKE to DCA sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 680 flights, with a median arrival 2 minutes early.
The national on-time rate over the same period is 77.3%, so Southwest on MKE to DCA runs 4 points behind the country as a whole. Across a thousand flights that is about 40 extra late arrivals.
Key figures
On time
73.3%
Arrivals under 15 minutes late, of 664 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
1.76%
National rate is 1.89%
Whole route
72.7%
Every carrier on MKE to DCA, 1,345 flights
These figures cover 680 flights between September 2025 and August 2026. Beyond the headline rate, 8.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Southwest against every carrier on MKE to DCA
Southwest flew 680 of the 1,345 flights on MKE to DCA, most of the route. Its 73.3% on time is about level with the route as a whole at 72.7%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Southwest at 73.3% to Republic at 57.1%. One 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines (this page) | 680 | 73.3% | 58 min | 1.76% | C |
| PSA Airlines | 658 | 72.3% | 144 min | 6.53% | C− |
| Republic Airwaysthin sample | 7 | 57.1% | 31 min | 0.00% | D+ |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 36 points, against half a point between the best and worst carrier.
- 5am–8am13 flights—
- 8am–11am320 flights89.5%
- 11am–2pm18 flights—
- 2pm–5pm79 flights64.6%
- 5pm–8pm250 flights53.5%
- 8pm–5am—
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 53.5% on time, against 89.5% for the 8am–11am 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 320 flights scheduled in it.
Across the year
Southwest on MKE to DCA through the year
Delays peak in March, when the on-time rate falls to 59.3%. December is the strongest month at 83.3%. Moving a flexible trip across that boundary buys 24 points. June was the busiest month here, with 60 flights.
Across the week, Monday is the strongest day at 78.4% on time and Friday the weakest at 66.3%, a spread of 12 points.
Arrival by arrival
How late Southwest on MKE to DCA runs when it is late
The 177 late arrivals split 57 under half an hour, 63 between 30 and 60 minutes, and 57 an hour or more.
- 15+ min early157 flights23.6%
- Within 15 min330 flights49.7%
- 15–29 min late57 flights8.6%
- 30–59 min late63 flights9.5%
- 1–2 hours late37 flights5.6%
- 2+ hours late20 flights3.0%
Scale runs 0% to 100%.
Share of 664 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 154 departures that left 15 minutes late or more, only 17 made it up before arrival. In the other direction, 40 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at DCA.
The worst days
Worst days for Southwest on MKE to DCA
The latest arrival of the period was on 17 February 2026, 4 hours 55 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 17 February 2026 | 4 hours 55 minutes | Carrier |
| 1 February 2026 | 3 hours 49 minutes | Late-arriving aircraft |
| 20 July 2026 | 3 hours 49 minutes | Carrier |
| 30 January 2026 | 3 hours 43 minutes | National Airspace System |
| 19 December 2025 | 3 hours 38 minutes | Carrier |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 43% of the 10,000 delay minutes carriers reported here, and the remaining four split what is left.
- 43%Late-arriving aircraft
- 39%National Airspace System
- 18%Carrier
- 1%Extreme weather
43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 10,000 reported delay minutes here, that single category outweighs weather by 43 to one. The split is drawn from 10,323 reported delay minutes.
39% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 3,980 minutes out of 10,000, against a national NAS share of 21%.
Cancellations sit at 1.76% against a national 1.89%, which is ordinary. Diversions add another 0.59%.
Connections and stage length
What a delay here costs
8.6% of arrivals land an hour or more late, close to the national 8.3%, so 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 634 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.
The return leg is a different operation and performs like one: it runs 82.5% on time across 681 flights, 9 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 9 points of difference.
One caution: this is a thin sample. 680 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 MKE to DCA
Put together: treat all of this as provisional. 680 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 73.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 664 completed flights over 12 months sit behind that.
Related
Where to go next
- MKE to DCA, every carrier
- Southwest on DCA to MKE, the return leg
- PSA Airlines on MKE to DCA72.3%
- Southwest Airlines network-wide record
- Milwaukee Mitchell International (MKE) delay statistics
- Ronald Reagan Washington National (DCA) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.