Route reliability record
SDF→DCA
Louisville to Washington
- Flights
- 1,025
- Period
- September 2025 to August 2026
- Distance
- 474 mi
- Carriers
- 4
This route carries a cancellation problem, not just a delay problem: 4.6% of scheduled flights never operate, against 1.9% nationally. Of the ones that do fly, about four flights in five arrive on time, worth a B− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 1,025 SDF to DCA flights, of which Republic Airways flew 463 at 83.4% on time.
Best time to fly SDF to DCA: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 90.0% of the time and Saturday flights 86.1%, against 78.2% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.2%
Arrivals under 15 minutes late, of 976 completed flights
Avg delay
87 min
Across delayed arrivals only, not all flights
Cancelled
4.59%
National rate is 1.89%
Best carrier
Republic
83.4% on time across 463 flights
These figures cover 1,025 flights between September 2025 and August 2026. The median arrival is 9 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Which airline is most reliable on SDF to DCA
The choice of carrier is not cosmetic here. Republic Airways arrives on time 83.4% of the time; PSA Airlines manages 73.4%. Sample sizes sit next to every figure, because a two-point gap across 544 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 13 | 91.7% | 38 min | 7.69% | A− |
| Republic Airways | 463 | 83.4% | 53 min | 2.16% | B |
| PSA Airlines | 544 | 73.4% | 107 min | 6.62% | C− |
| American Airlinesthin sample | 5 | 60.0% | 69 min | 0.00% | D+ |
PSA Airlines cancels 6.6% 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.
Flight by flight
Flights on SDF to DCA
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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.
Best ways to make this trip
The most reliable ways to fly Louisville to Washington
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 1 of the top 3 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SDF → BWILouisville to Baltimore | Southwest Airlines | 85.1% | 86.7% | 1.82% | 5am–8am, Mon | — |
| 2. SDF → DCALouisville to Washington | Republic Airways | 81.6% | 83.4% | 2.16% | 5am–8am, Wed | YX 4549 06:00 |
| 3. SDF → DCALouisville to Washington | PSA Airlines | 68.5% | 73.4% | 6.62% | 8am–11am, Sat | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 32 points, against 10 points between the best and worst carrier.
- 5am–8am356 flights90.0%
- 8am–11am118 flights86.1%
- 11am–2pm223 flights77.1%
- 2pm–5pm212 flights57.8%
- 5pm–8pm116 flights71.6%
- 8pm–5am—
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.0% of the time, against 57.8% for the afternoon window. That is 32 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 356 flights scheduled in it.
Explore
Filter SDF to DCA by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SDF to DCA, the best departure window is 5am–8am at 90.0% on time and the worst is 2pm–5pm at 57.8%, a wide gap of 32.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am90.0%
- 8–11am86.1%
- 11am–2pm77.1%
- 2–5pm57.8%
- 5–8pm71.6%
- 8pm–5am—
best all US flightsScale 50% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 18 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.
June is the worst month at 69.1% on time, 18 points below October, the best at 87.1%. 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 93 flights.
Across the week, Saturday is the strongest day at 86.1% on time and Sunday the weakest at 73.9%, a spread of 12 points.
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 19,000 reported delay minutes.
- 38%Late-arriving aircraft
- 34%Carrier
- 28%National Airspace System
- 0%Extreme weather
- 0%Security
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 19,000 reported delay minutes here, that single category outweighs weather by 38 to one. The split is drawn from 18,547 reported delay minutes.
The largest share of delay minutes, 34%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 6,308 of the 19,000 delay minutes reported here.
Cancellations run at 4.59%, against 1.89% nationally. That is roughly one flight in twenty 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
7.8% 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 an hour and a half, which a normal layover absorbs.
At 474 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 74.9% on time across 1,027 flights, 3 points below 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 3 points of difference.
One caution: this is a thin sample. 1,025 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.
Work out the risk of missing a connection in DCA after this flight
What to do with this
Booking this route
Put together: the delay figures matter less here than the 4.59% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 976 completed flights over 12 months sit behind that.
Common questions
SDF to DCA questions
How often is SDF to DCA delayed?
Roughly one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.8% of the 1,025 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on SDF to DCA?
Republic Airways leads at 83.4% on time across 463 flights. PSA Airlines is at the other end on 73.4%, a gap of 10 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 SDF to DCA?
The 5am–8am departure window is the strongest at 90.0% on time. The 2pm–5pm window is the weakest at 57.8%, 32 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 June delays on SDF to DCA?
June is the weakest month at 69.1% on time, compared with 87.1% in October. Across the year that is 18 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 SDF — the return legseparate record
- Ronald Reagan Washington National (DCA) delay statistics
- Republic Airways on SDF to DCA83.4%
- PSA Airlines on SDF to DCA73.4%
- SDF to ORD, a related route79.3%
- BOS to DCA, a related route72.6%
- SDF to ATL, a related route89.6%
- Envoy Air on-time record91.7%
- Republic Airways on-time record83.4%
- PSA Airlines on-time record73.4%
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
Direction matters. SDF to DCA and DCA to SDF are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Embed SDF to DCA’s on-time badge on your site
Paste this into a web page. The badge shows the current on-time rate, cancellation rate and grade, and updates every month. Preview it, or build a badge for another route or airport.
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.