Route reliability record
SDF→ORD
Louisville to Chicago
- Flights
- 2,807
- Period
- July 2025 to June 2026
- Distance
- 286 mi
- Carriers
- 5
This route lands a B, about a point better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 2,807 flights, of which Republic Airways flew 1,736 at 82.5% on time.
Republic Airways is the most reliable of the three carriers covered here at 82.5% on time across 1,736 flights.
Key figures
On time
79.0%
Arrivals under 15 minutes late, of 2,724 completed flights
Avg delay
78 min
Across delayed arrivals only, not all flights
Cancelled
2.81%
National rate is 1.81%
Best carrier
Republic
82.5% on time across 1,736 flights
These figures cover 2,807 flights between July 2025 and June 2026. Beyond the headline rate, 8.4% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on SDF to ORD
The choice of carrier is not cosmetic here. Republic Airways arrives on time 82.5% of the time; SkyWest Airlines manages 70.9%. Sample sizes sit next to every figure, because a two-point gap across 645 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airways | 1,736 | 82.5% | 67 min | 2.71% | B |
| Envoy Air | 416 | 77.5% | 78 min | 1.44% | B |
| SkyWest Airlines | 645 | 70.9% | 96 min | 3.88% | C− |
| American Airlinesthin sample | 3 | 66.7% | 48 min | 0.00% | C+ |
| United Airlinesthin sample | 6 | 50.0% | 54 min | 0.00% | F+ |
SkyWest Airlines cancels 3.9% 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.
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 21 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am846 flights86.0%
- 8am–11am601 flights84.2%
- 11am–2pm368 flights82.5%
- 2pm–5pm414 flights72.9%
- 5pm–8pm575 flights64.8%
- 8pm–5am3 flights—
Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 64.8% on time, against 86.0% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5am–8am window is the busiest, with 846 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 19 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 71.0% on time, 19 points below September, the best at 89.6%. 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. May was the busiest month here, with 312 flights.
Across the week, Thursday is the strongest day at 84.8% on time and Friday the weakest at 74.5%. 10 points is a smaller lever than departure hour, but it is free.
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 45,000 reported delay minutes.
- 39%National Airspace System
- 38%Late-arriving aircraft
- 17%Carrier
- 6%Extreme weather
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 45,000 reported delay minutes here, that single category outweighs weather by 6 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 44,533 reported delay minutes.
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 17,000 minutes out of 45,000, against a national NAS share of 21%.
Cancellations run at 2.81%, against 1.81% nationally. That is roughly one flight in 40 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
8.4% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the a little over an hour kind, which a normal layover absorbs.
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 75.3% on time across 2,804 flights, 4 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 4 points of difference.
The sample behind these figures is 2,807 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.
What to do with this
Booking this route
Put together: the delay figures matter less here than the 2.81% 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. 2,724 completed flights over 12 months sit behind that.
Common questions
SDF to ORD questions
How often is SDF to ORD delayed?
About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.0% of the 2,807 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on SDF to ORD?
Republic Airways leads at 82.5% on time across 1,736 flights. SkyWest Airlines is at the other end on 70.9%, a gap of 12 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 SDF to ORD?
The 5am–8am departure window is the strongest at 86.0% on time. The 5pm–8pm window is the weakest at 64.8%, 21 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 SDF to ORD?
July is the weakest month at 71.0% on time, compared with 89.6% in September. Across the year that is 19 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
- ORD to SDF — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- Republic Airways on-time record82.5%
- Envoy Air on-time record77.5%
- SkyWest Airlines on-time record70.9%
- Why the first flight of the morning is statistically safest
- What a cancellation rate actually tells you (and what it hides)
Direction matters. SDF to ORD and ORD to SDF are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.