Route reliability record
ORD→SDF
Chicago to Louisville
- Flights
- 2,792
- Period
- September 2025 to August 2026
- Distance
- 286 mi
- Carriers
- 5
This route carries a cancellation problem, not just a delay problem: 3.6% of scheduled flights never operate, against 1.9% nationally. Of the ones that do fly, close to three flights in four 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 2,792 ORD to SDF flights, of which Republic Airways flew 1,850 at 75.8% on time.
Best time to fly ORD to SDF: a 5am–8am departure, ideally on a Thursday. Flights in that window arrived on time 83.9% of the time and Thursday flights 80.2%, against 75.8% 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
75.8%
Arrivals under 15 minutes late, of 2,690 completed flights
Avg delay
71 min
Across delayed arrivals only, not all flights
Cancelled
3.58%
National rate is 1.89%
Best carrier
Republic
75.8% on time across 1,850 flights
These figures cover 2,792 flights between September 2025 and August 2026. Beyond the headline rate, 9.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on ORD to SDF
The two carriers here are closely matched: 3 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 282 | 84.6% | 51 min | 1.06% | B |
| Republic Airways | 1,850 | 75.8% | 77 min | 4.11% | B− |
| SkyWest Airlines | 650 | 72.4% | 61 min | 3.08% | C− |
| American Airlinesthin sample | 4 | 50.0% | 71 min | 0.00% | F+ |
| United Airlinesthin sample | 5 | 20.0% | 45 min | 0.00% | F+ |
Republic Airways cancels 4.1% 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 ORD to SDF
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.
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Best ways to make this trip
The most reliable ways to fly Chicago 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 3 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. MDW → SDFChicago to Louisville | Southwest Airlines | 81.7% | 83.1% | 1.66% | 5am–8am, Wed | — |
| 2. ORD → SDFChicago to Louisville | Republic Airways | 72.7% | 75.8% | 4.11% | 5am–8am, Thu | YX 3551 19:52 |
| 3. ORD → SDFChicago to Louisville | SkyWest Airlines | 70.2% | 72.4% | 3.08% | 11am–2pm, Wed | — |
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 10 points, against 3 points between the best and worst carrier.
- 5am–8am256 flights83.9%
- 8am–11am419 flights75.5%
- 11am–2pm219 flights81.9%
- 2pm–5pm597 flights73.7%
- 5pm–8pm709 flights74.5%
- 8pm–5am592 flights73.5%
Scale runs 65% to 90%.
Book the early departure. Flights leaving between 5am–8am arrive on time 83.9% of the time, against 73.5% for the overnight window. That is 10 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 709 flights scheduled in it.
Explore
Filter ORD 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 ORD to SDF, the best departure window is 5am–8am at 83.9% on time and the worst is 8pm–5am at 73.5%, a wide gap of 10.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am83.9%
- 8–11am75.5%
- 11am–2pm81.9%
- 2–5pm73.7%
- 5–8pm74.5%
- 8pm–5am73.5%
best all US flightsScale 60% to 95%.
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.
December is the weak month at 62.7% on time, against 88.7% in September. 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. April was the busiest month here, with 312 flights.
Across the week, Thursday is the strongest day at 80.2% on time and Sunday the weakest at 70.6%, a spread of 10 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 51% of the 46,000 delay minutes carriers reported here, and the remaining four split what is left.
- 51%Late-arriving aircraft
- 23%Carrier
- 20%National Airspace System
- 7%Extreme weather
51% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 46,000 reported delay minutes here, that single category outweighs weather by 7 to one. The split is drawn from 46,360 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 83.9% on time here.
Cancellations run at 3.58%, against 1.89% nationally. That is about one flight in 30 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
9.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
At 286 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 79.3% on time across 2,795 flights, 4 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 4 points of difference.
The sample behind these figures is 2,792 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
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 3.58% cancellation rate. A late arrival costs you a little over an hour; 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. 2,690 completed flights over 12 months sit behind that.
Common questions
ORD to SDF questions
How often is ORD to SDF delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.2% of the 2,792 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on ORD to SDF?
Republic Airways leads at 75.8% on time across 1,850 flights. SkyWest Airlines is at the other end on 72.4%, a gap of 3 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 ORD to SDF?
The 5am–8am departure window is the strongest at 83.9% on time. The 8pm–5am window is the weakest at 73.5%, 10 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 ORD to SDF?
December is the weakest month at 62.7% on time, compared with 88.7% in September. 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 ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- Envoy Air on ORD to SDF84.6%
- Republic Airways on ORD to SDF75.8%
- SkyWest Airlines on ORD to SDF72.4%
- ORD to LGA, a related route66.6%
- ATL to SDF, a related route84.3%
- ORD to BOS, a related route66.6%
- Envoy Air on-time record84.6%
- Republic Airways on-time record75.8%
- SkyWest Airlines on-time record72.4%
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
Direction matters. ORD to SDF and SDF to ORD 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.