Route reliability record
EWR→SDF
Newark to Louisville
- Flights
- 1,020
- Period
- September 2025 to August 2026
- Distance
- 642 mi
- Carriers
- 3
This route carries a cancellation problem, not just a delay problem: 5.8% 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 1,020 EWR to SDF flights, with a median arrival 13 minutes early.
Best time to fly EWR to SDF: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 85.8% of the time and Tuesday flights 82.9%, against 80.7% 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
80.7%
Arrivals under 15 minutes late, of 960 completed flights
Avg delay
84 min
Across delayed arrivals only, not all flights
Cancelled
5.78%
National rate is 1.89%
Best carrier
Republic
80.8% on time across 1,016 flights
These figures cover 1,020 flights between September 2025 and August 2026. The median arrival is 13 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 EWR 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 |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| Republic Airways | 1,016 | 80.8% | 84 min | 5.81% | B− |
| United Airlinesthin sample | 3 | 66.7% | 62 min | 0.00% | C+ |
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 Newark 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. 1 of the top 2 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. LGA → SDFNew York to Louisville | Republic Airways | 76.8% | 80.0% | 3.97% | 8am–11am, Tue (route) | YX 5643 08:30 |
| 2. EWR → SDFNewark to Louisville | Republic Airways | 76.1% | 80.8% | 5.81% | 8am–11am, Tue (route) | — |
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 14 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am302 flights85.8%
- 11am–2pm35 flights71.4%
- 2pm–5pm15 flights—
- 5pm–8pm305 flights80.6%
- 8pm–5am363 flights76.5%
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 71.4% on time against 85.8% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8pm–5am window is the busiest, with 363 flights scheduled in it.
Explore
Filter EWR 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 EWR to SDF, the best departure window is 8am–11am at 85.8% on time and the worst is 11am–2pm at 71.4%, a wide gap of 14.4 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am—
- 8–11am85.8%
- 11am–2pm71.4%
- 2–5pm—
- 5–8pm80.6%
- 8pm–5am76.5%
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 21 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 71.6% on time, 21 points below May, the best at 92.1%. 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. August was the busiest month here, with 93 flights.
Across the week, Tuesday is the strongest day at 82.9% on time and Sunday the weakest at 72.5%, a spread of 10 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 45% of the 16,000 delay minutes carriers reported here, and the remaining four split what is left.
- 45%Late-arriving aircraft
- 26%Carrier
- 19%National Airspace System
- 10%Extreme weather
45% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 16,000 reported delay minutes here, that single category outweighs weather by 5 to one. The split is drawn from 15,578 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 85.8% on time here.
Cancellations run at 5.78%, against 1.89% nationally. That is roughly one flight in fifteen 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
7.3% 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.
The 642 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.
The return leg is a different operation and performs like one: it runs 87.4% on time across 1,019 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. 1,020 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: the delay figures matter less here than the 5.78% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 8am–11am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 960 completed flights over 12 months sit behind that.
Common questions
EWR to SDF questions
How often is EWR 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 19.3% of the 1,020 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
How reliable is EWR to SDF compared with the rest of the country?
80.7% 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 EWR to SDF?
The 8am–11am departure window is the strongest at 85.8% on time. The 11am–2pm window is the weakest at 71.4%, 14 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 EWR to SDF?
July is the weakest month at 71.6% on time, compared with 92.1% in May. Across the year that is 21 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 EWR — the return legseparate record
- Newark Liberty International (EWR) delay statistics
- EWR to MCO, a related route77.9%
- ORD to SDF, a related route75.8%
- EWR to ATL, a related route76.9%
- Spirit Airlines on-time record100.0%
- Republic Airways on-time record80.8%
- United Airlines on-time record66.7%
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
Direction matters. EWR to SDF and SDF to EWR 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.