Route reliability record
ORD→SDF
Chicago to Louisville
- Flights
- 2,804
- Period
- July 2025 to June 2026
- Distance
- 286 mi
- Carriers
- 5
This route carries a cancellation problem, not just a delay problem: 3.3% of scheduled flights never operate, against 1.8% 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 2,804 flights, of which Envoy Air flew 415 at 84.1% on time.
Envoy Air is the most reliable of the three carriers covered here at 84.1% on time across 415 flights.
Key figures
On time
75.3%
Arrivals under 15 minutes late, of 2,706 completed flights
Avg delay
71 min
Across delayed arrivals only, not all flights
Cancelled
3.32%
National rate is 1.81%
Best carrier
Envoy
84.1% on time across 415 flights
These figures cover 2,804 flights between July 2025 and June 2026. Beyond the headline rate, 9.8% 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 ORD to SDF
The choice of carrier is not cosmetic here. Envoy Air arrives on time 84.1% of the time; SkyWest Airlines manages 71.0%. 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 |
|---|---|---|---|---|---|
| Envoy Air | 415 | 84.1% | 54 min | 1.20% | B |
| Republic Airways | 1,733 | 75.0% | 75 min | 3.87% | B− |
| SkyWest Airlines | 645 | 71.0% | 69 min | 3.10% | C− |
| American Airlinesthin sample | 4 | 50.0% | 71 min | 0.00% | F+ |
| United Airlinesthin sample | 6 | 33.3% | 45 min | 0.00% | F+ |
Republic Airways 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 14 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am263 flights86.2%
- 8am–11am380 flights73.7%
- 11am–2pm270 flights80.6%
- 2pm–5pm593 flights73.8%
- 5pm–8pm708 flights74.1%
- 8pm–5am590 flights71.9%
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 86.2% of the time, against 71.9% for the overnight window. That is 14 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 708 flights scheduled in it.
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, Tuesday is the strongest day at 78.7% on time and Sunday the weakest at 70.9%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 51% of the 48,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 51%Late-arriving aircraft
- 22%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. That is a cascade, and cascades start small and grow through the day. Across 48,000 reported delay minutes here, that single category outweighs weather by 7 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 47,649 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 86.2% on time here.
Cancellations run at 3.32%, against 1.81% 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
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.8% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum 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 79.0% on time across 2,807 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 2,804 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 3.32% 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. 2,706 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 arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.7% of the 2,804 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 ORD to SDF?
Envoy Air leads at 84.1% on time across 415 flights. SkyWest Airlines is at the other end on 71.0%, a gap of 13 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 86.2% on time. The 8pm–5am window is the weakest at 71.9%, 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 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-time record84.1%
- Republic Airways on-time record75.0%
- SkyWest Airlines on-time record71.0%
- Why the first flight of the morning is statistically safest
- What a cancellation rate actually tells you (and what it hides)
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.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.