Route reliability record
SDF→EWR
Louisville to Newark
- Flights
- 1,019
- Period
- September 2025 to August 2026
- Distance
- 642 mi
- Carriers
- 3
This route carries a cancellation problem, not just a delay problem: 4.7% of scheduled flights never operate, against 1.9% nationally. Of the ones that do fly, close to nine flights in ten arrive on time, worth an A− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 1,019 SDF to EWR flights, with a median arrival 13 minutes early.
Best time to fly SDF to EWR: a 8am–11am departure, ideally on a Wednesday. Flights in that window arrived on time 94.0% of the time and Wednesday flights 93.1%, against 87.4% for the route overall.
Set against the rest of the country, this route's record is 10 points better than the US average of 77.3%. That gap is worth roughly 101 fewer late arrivals for every thousand flights.
Key figures
On time
87.4%
Arrivals under 15 minutes late, of 965 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
4.71%
National rate is 1.89%
Best carrier
Republic
87.5% on time across 1,015 flights
These figures cover 1,019 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 SDF to EWR
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 | 1,015 | 87.5% | 66 min | 4.73% | A− |
| United Airlinesthin sample | 3 | 33.3% | 87 min | 0.00% | F+ |
Flight by flight
Flights on SDF to EWR
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 Newark
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. SDF → EWRLouisville to Newark | Republic Airways | 83.4% | 87.5% | 4.73% | 8am–11am, Wed (route) | YX 3594 06:15 |
| 2. SDF → LGALouisville to New York | Republic Airways | 79.4% | 83.2% | 4.55% | 5am–8am, Fri (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 13 points, against half a point between the best and worst carrier.
- 5am–8am343 flights89.8%
- 8am–11am243 flights94.0%
- 11am–2pm333 flights81.4%
- 2pm–5pm99 flights81.7%
- 5pm–8pm1 flights—
- 8pm–5am—
Scale runs 75% to 100%. 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 81.4% on time against 94.0% 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 5am–8am window is the busiest, with 343 flights scheduled in it.
Explore
Filter SDF to EWR 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 EWR, the best departure window is 8am–11am at 94.0% on time and the worst is 11am–2pm at 81.4%, a wide gap of 12.6 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am89.8%
- 8–11am94.0%
- 11am–2pm81.4%
- 2–5pm81.7%
- 5–8pm—
- 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 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.
December is the weak month at 73.2% on time, against 96.6% in May. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. October was the busiest month here, with 93 flights.
Across the week, Wednesday is the strongest day at 93.1% on time and Monday the weakest at 80.1%, a spread of 13 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 8,058 reported delay minutes.
- 39%National Airspace System
- 30%Late-arriving aircraft
- 28%Carrier
- 4%Extreme weather
39% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 3,111 minutes out of 8,058, against a national NAS share of 21%. The split is drawn from 8,058 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 94.0% on time here.
Cancellations run at 4.71%, against 1.89% nationally. That is about 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
5.2% 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 about an hour, 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 80.7% on time across 1,020 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. 1,019 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 EWR after this flight
What to do with this
Booking this route
Put together: the delay figures matter less here than the 4.71% cancellation rate. A late arrival costs you about an hour; 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. 965 completed flights over 12 months sit behind that.
Common questions
SDF to EWR questions
How often is SDF to EWR 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 12.6% of the 1,019 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is SDF to EWR compared with the rest of the country?
87.4% of flights arrive on time here against a national 77.3%, a difference of 10 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 EWR?
The 8am–11am departure window is the strongest at 94.0% on time. The 11am–2pm window is the weakest at 81.4%, 13 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 December delays on SDF to EWR?
December is the weakest month at 73.2% on time, compared with 96.6% in May. 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
- EWR to SDF — the return legseparate record
- Newark Liberty International (EWR) delay statistics
- SDF to ORD, a related route79.3%
- MCO to EWR, a related route75.0%
- SDF to ATL, a related route89.6%
- Spirit Airlines on-time record100.0%
- Republic Airways on-time record87.5%
- United Airlines on-time record33.3%
- The US routes with the most cancellations
- The best time of day to fly, according to 7.05 million flight records
Direction matters. SDF to EWR and EWR 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.