Route reliability record
SDF→BWI
Louisville to Baltimore
- Flights
- 880
- Period
- September 2025 to August 2026
- Distance
- 495 mi
- Carriers
- 1
This route earns an A. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 880 SDF to BWI flights, with a median arrival 10 minutes early.
Best time to fly SDF to BWI: a 5am–8am departure, ideally on a Monday. Flights in that window arrived on time 95.6% of the time and Monday flights 90.9%, against 86.7% for the route overall.
Set against the rest of the country, this route's record is 9 points better than the US average of 77.3%. That gap is worth roughly 94 fewer late arrivals for every thousand flights.
Key figures
On time
86.7%
Arrivals under 15 minutes late, of 859 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
1.82%
National rate is 1.89%
Best carrier
Southwest
86.7% on time across 880 flights
These figures cover 880 flights between September 2025 and August 2026. The median arrival is 10 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 SDF to BWI
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 | 880 | 86.7% | 63 min | 1.82% | A |
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Best ways to make this trip
The most reliable ways to fly Louisville to Baltimore
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. 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 27 points, against half a point between the best and worst carrier.
- 5am–8am345 flights95.6%
- 8am–11am79 flights84.8%
- 11am–2pm103 flights94.1%
- 2pm–5pm216 flights80.9%
- 5pm–8pm137 flights68.7%
- 8pm–5am—
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 95.6% of the time, against 68.7% for the evening window. That is 27 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 345 flights scheduled in it.
Explore
Filter SDF to BWI 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 BWI, the best departure window is 5am–8am at 95.6% on time and the worst is 5pm–8pm at 68.7%, a wide gap of 26.9 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am95.6%
- 8–11am84.8%
- 11am–2pm94.1%
- 2–5pm80.9%
- 5–8pm68.7%
- 8pm–5am—
best all US flightsScale 60% to 100%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 17 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 78.2% on time, 17 points below January, the best at 94.9%. 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 95 flights.
Across the week, Monday is the strongest day at 90.9% on time and Sunday the weakest at 76.3%, a spread of 15 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 7,217 reported delay minutes.
- 38%Carrier
- 33%Late-arriving aircraft
- 27%National Airspace System
- 2%Extreme weather
The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,719 of the 7,217 delay minutes reported here. The split is drawn from 7,217 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 95.6% on time here.
Cancellations sit at 1.82% against a national 1.89%, which is ordinary. Diversions add another 0.57%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 2.9% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 80.0% on time across 891 flights, 7 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 7 points of difference.
One caution: this is a thin sample. 880 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 BWI after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 880 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 86.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 859 completed flights over 12 months sit behind that.
Common questions
SDF to BWI questions
How often is SDF to BWI delayed?
About one flight in eight arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 13.3% of the 880 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is SDF to BWI compared with the rest of the country?
86.7% of flights arrive on time here against a national 77.3%, a difference of 9 points in its favour. That is worth a A on this site's grading scale.
What time of day has the fewest delays on SDF to BWI?
The 5am–8am departure window is the strongest at 95.6% on time. The 5pm–8pm window is the weakest at 68.7%, 27 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 BWI?
June is the weakest month at 78.2% on time, compared with 94.9% in January. Across the year that is 17 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
- BWI to SDF — the return legseparate record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- SDF to ORD, a related route79.3%
- ATL to BWI, a related route75.2%
- SDF to ATL, a related route89.6%
- Southwest Airlines on-time record86.7%
- 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. SDF to BWI and BWI to SDF 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.