Route reliability record
BWI→SDF
Baltimore to Louisville
- Flights
- 891
- Period
- September 2025 to August 2026
- Distance
- 495 mi
- Carriers
- 1
This route lands a B, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That rests on 891 BWI to SDF flights, with a median arrival 5 minutes early.
Best time to fly BWI to SDF: a 11am–2pm departure, ideally on a Tuesday. Flights in that window arrived on time 91.9% of the time and Tuesday flights 88.6%, against 80.0% 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
80.0%
Arrivals under 15 minutes late, of 869 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
2.47%
National rate is 1.89%
Best carrier
Southwest
80.0% on time across 891 flights
These figures cover 891 flights between September 2025 and August 2026. The median arrival is 5 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.
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Carrier by carrier
Which airline is most reliable on BWI to SDF
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 | 891 | 80.0% | 53 min | 2.47% | B |
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Best ways to make this trip
The most reliable ways to fly Baltimore to Louisville
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. 2 of the top 3 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. BWI → SDFBaltimore to Louisville | Southwest Airlines | 78.0% | 80.0% | 2.47% | 11am–2pm, Tue | — |
| 2. DCA → SDFWashington to Louisville | PSA Airlines | 72.6% | 76.7% | 5.33% | 5am–8am, Sat | — |
| 3. DCA → SDFWashington to Louisville | Republic Airways | 68.6% | 72.5% | 5.38% | 8am–11am, Sat | YX 4672 19:45 |
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 22 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am230 flights88.5%
- 11am–2pm135 flights91.9%
- 2pm–5pm98 flights70.4%
- 5pm–8pm90 flights75.9%
- 8pm–5am338 flights73.0%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 91.9% on time, ahead of 2pm–5pm at 70.4%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 8pm–5am window is the busiest, with 338 flights scheduled in it.
Explore
Filter BWI to SDF 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 BWI to SDF, the best departure window is 11am–2pm at 91.9% on time and the worst is 2pm–5pm at 70.4%, a wide gap of 21.5 points. All US flights leaving 11am–2pm ran 78.3%.
- 5–8am—
- 8–11am88.5%
- 11am–2pm91.9%
- 2–5pm70.4%
- 5–8pm75.9%
- 8pm–5am73.0%
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 26 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.
Delays peak in May, when the on-time rate falls to 70.0%. February is the strongest month at 96.4%. Moving a flexible trip across that boundary buys 26 points. October was the busiest month here, with 95 flights.
Across the week, Tuesday is the strongest day at 88.6% on time and Sunday the weakest at 73.4%, a spread of 15 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 50% of the 9,152 delay minutes carriers reported here, and the remaining four split what is left.
- 50%Late-arriving aircraft
- 36%Carrier
- 12%National Airspace System
- 2%Extreme weather
50% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 9,152 reported delay minutes here, that single category outweighs weather by 32 to one. The split is drawn from 9,152 reported delay minutes.
The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 3,325 of the 9,152 delay minutes reported here.
Cancellations sit at 2.47% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here actually costs
6.8% 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 roughly 55 minutes, which a normal layover absorbs.
At 495 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 11am–2pm window matters as much as it does.
The return leg is a different operation and performs like one: it runs 86.7% on time across 880 flights, 7 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 7 points of difference.
One caution: this is a thin sample. 891 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 SDF after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 891 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 80.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 869 completed flights over 12 months sit behind that.
Common questions
BWI to SDF questions
How often is BWI to SDF delayed?
About 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 20.0% of the 891 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 55 minutes on average.
How reliable is BWI to SDF compared with the rest of the country?
80.0% of flights arrive on time here against a national 77.3%, a difference of 3 points in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on BWI to SDF?
The 11am–2pm departure window is the strongest at 91.9% on time. The 2pm–5pm window is the weakest at 70.4%, 22 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 May delays on BWI to SDF?
May is the weakest month at 70.0% on time, compared with 96.4% in February. Across the year that is 26 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
- SDF to BWI — the return legseparate record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- BWI to ATL, a related route79.9%
- ORD to SDF, a related route75.8%
- BWI to MCO, a related route75.5%
- Southwest Airlines on-time record80.0%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. BWI to SDF and SDF to BWI are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.