Route reliability record
STL→DCA
St. Louis to Washington
- Flights
- 2,414
- Period
- July 2025 to June 2026
- Distance
- 719 mi
- Carriers
- 5
This route sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 2,414 flights, of which PSA Airlines flew 615 at 74.1% on time.
The national on-time rate over the same period is 77.6%, so this route runs 5 points behind the country as a whole. Across a thousand flights that is about 47 extra late arrivals.
Key figures
On time
72.9%
Arrivals under 15 minutes late, of 2,331 completed flights
Avg delay
76 min
Across delayed arrivals only, not all flights
Cancelled
2.65%
National rate is 1.81%
Best carrier
PSA
74.1% on time across 615 flights
These figures cover 2,414 flights between July 2025 and June 2026. Beyond the headline rate, 9.3% 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
Which airline is most reliable on STL to DCA
The two carriers here are closely matched: 2 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 199 | 77.1% | 62 min | 3.52% | B− |
| PSA Airlines | 615 | 74.1% | 128 min | 5.20% | C− |
| Envoy Airthin sample | 22 | 72.7% | 32 min | 0.00% | C+ |
| Southwest Airlines | 1,403 | 72.5% | 57 min | 1.43% | C |
| American Airlinesthin sample | 175 | 67.5% | 83 min | 2.86% | C |
PSA Airlines cancels 5.2% 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.
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 36 points, against 2 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am340 flights82.7%
- 8am–11am601 flights85.5%
- 11am–2pm448 flights71.7%
- 2pm–5pm462 flights67.0%
- 5pm–8pm477 flights61.1%
- 8pm–5am86 flights50.0%
Scale runs 40% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 50.0% on time, against 85.5% 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 601 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 23 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.
July is the worst month at 58.5% on time, 23 points below April, the best at 81.8%. 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. October was the busiest month here, with 223 flights.
Across the week, Saturday is the strongest day at 82.9% on time and Sunday the weakest at 66.1%. 17 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 48,000 reported delay minutes.
- 39%Late-arriving aircraft
- 35%Carrier
- 23%National Airspace System
- 3%Extreme weather
- 0%Security
39% 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 48,000 reported delay minutes here, that single category outweighs weather by 14 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 47,775 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 17,000 of the 48,000 delay minutes reported here.
Cancellations run at 2.65%, against 1.81% nationally. That is about one flight in 40 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.3% 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 719 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 73.6% on time across 2,414 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.
The sample behind these figures is 2,414 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. April runs 81.8% on time and July 58.5%, a swing of 23 points. If the dates move at all, move them out of July before you think about anything else. 2,331 completed flights over 12 months sit behind that.
Common questions
STL to DCA questions
How often is STL to DCA delayed?
About 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 27.1% of the 2,414 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 STL to DCA?
PSA Airlines leads at 74.1% on time across 615 flights. Southwest Airlines is at the other end on 72.5%, a gap of 2 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 STL to DCA?
The 8am–11am departure window is the strongest at 85.5% on time. The 8pm–5am window is the weakest at 50.0%, 36 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 STL to DCA?
July is the weakest month at 58.5% on time, compared with 81.8% in April. Across the year that is 23 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- DCA to STL — the return legseparate record
- St. Louis Lambert International (STL) delay statistics
- Ronald Reagan Washington National (DCA) delay statistics
- Republic Airways on-time record77.1%
- PSA Airlines on-time record74.1%
- Envoy Air on-time record72.7%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. STL to DCA and DCA to STL 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.