Carrier route record
WNMCI→DCA
Southwest Airlines · Kansas City to Washington
- Flights
- 999
- Period
- July 2025 to June 2026
- Share of route
- 52%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on MCI 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, 5 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 999 flights, with a median arrival 3 minutes early.
The national on-time rate over the same period is 77.6%, so Southwest on MCI to DCA runs 5 points behind the country as a whole. Across a thousand flights that is about 45 extra late arrivals.
Key figures
On time
73.1%
Arrivals under 15 minutes late, of 978 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
1.20%
National rate is 1.81%
Whole route
74.8%
Every carrier on MCI to DCA, 1,926 flights
These figures cover 999 flights between July 2025 and June 2026. Beyond the headline rate, 9.0% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Southwest against every carrier on MCI to DCA
Southwest flew 999 of the 1,926 flights on MCI to DCA, most of the route. Its 73.1% on time is 2 points worse than the route as a whole, which runs 74.8%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from Envoy at 90.2% to PSA at 72.8%. Three 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 |
|---|---|---|---|---|---|
| Envoy Airthin sample | 168 | 90.2% | 85 min | 2.38% | A |
| American Airlinesthin sample | 25 | 80.0% | 41 min | 0.00% | B+ |
| Republic Airwaysthin sample | 152 | 74.8% | 36 min | 0.66% | C+ |
| Southwest Airlines (this page) | 999 | 73.1% | 58 min | 1.20% | C |
| PSA Airlines | 582 | 72.8% | 136 min | 7.04% | C− |
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 43 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–8am237 flights89.2%
- 8am–11am107 flights95.3%
- 11am–2pm325 flights74.1%
- 2pm–5pm19 flights—
- 5pm–8pm303 flights51.9%
- 8pm–5am8 flights—
Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 51.9% on time, against 95.3% 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 11am–2pm window is the busiest, with 325 flights scheduled in it.
Across the year
Southwest on MCI to DCA through the year
Delays peak in May, when the on-time rate falls to 58.0%. January is the strongest month at 87.3%. Moving a flexible trip across that boundary buys 29 points. December was the busiest month here, with 89 flights.
Across the week, Saturday is the strongest day at 85.0% on time and Sunday the weakest at 68.0%. 17 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 47% of the 15,000 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.
- 47%Late-arriving aircraft
- 30%National Airspace System
- 19%Carrier
- 3%Extreme weather
- 2%Security
47% 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 15,000 reported delay minutes here, that single category outweighs weather by 18 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 15,272 reported delay minutes.
The practical consequence: the 8am–11am 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 1.20% against a national 1.81%, which is ordinary. Diversions add another 0.90%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.0% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 949 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 72.7% on time across 999 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 999 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 MCI to DCA
Put together: treat all of this as provisional. 999 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 73.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 978 completed flights over 12 months sit behind that.
Related
Where to go next
- MCI to DCA, every carrier
- Southwest on DCA to MCI, the return leg
- Envoy Air on MCI to DCA90.2%
- Republic Airways on MCI to DCA74.8%
- PSA Airlines on MCI to DCA72.8%
- Southwest Airlines network-wide record
- Kansas City International (MCI) delay statistics
- Ronald Reagan Washington National (DCA) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.