Best time to fly out of Louisville (SDF)
The early-flight folk wisdom holds up at Louisville Muhammad Ali: departures in the Before 6am band left on time 92.8% of the time, against 66.1% in the 8–10pm band. These are historical odds, not forecasts. The records say what happened on this schedule over three years; they know nothing about tomorrow’s thunderstorm.
Data through June 2026 · Bureau of Transportation Statistics
On-time rate by hour and day
On this page, “on time” means a departure that pushed back less than 15 minutes behind its scheduled time — the Bureau of Transportation Statistics definition, and the one airlines are held to.
| Departure time | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Before 6am | 94 | 92 | 91 | 94 | 94 | 92 | 94 |
| 6–8am | 91 | 92 | 93 | 92 | 90 | 90 | 90 |
| 8–10am | 89 | 92 | 93 | 92 | 89 | 90 | 88 |
| 10am–12pm | 86 | 86 | 88 | 86 | 83 | 83 | 83 |
| 12–2pm | 82 | 87 | 87 | 84 | 82 | 82 | 81 |
| 2–4pm | 80 | 84 | 85 | 77 | 77 | 80 | 75 |
| 4–6pm | 77 | 80 | 78 | 73 | 73 | 75 | 71 |
| 6–8pm | 74 | 75 | 75 | 68 | 73 | 71 | 68 |
| 8–10pm | 66 | 76 | 72 | 66 | 67 | 71 | 59 |
| 10pm–12am | – | – | – | – | – | – | – |
The steadiest stretch at SDF was Before 6am — 92.8% of departures left on time across 2,128 flights. The weakest was 8–10pm at 66.1%. 6–8am departures from SDF left on time 91.1% of the time across 17,252 flights; 6–8pm departures, 71.9% across 6,938. That is a gap of 19.2 points, and it is the whole case for the early flight.
The year at SDF
July was the hard month at SDF: 76.8% of departures left on time, across 6,518 flights. October was the easy one at 87.5%. Each month pools three years of that month, so a single bad week does not decide it.
| Month | Share departures that left on time | Flights |
|---|---|---|
| January | 82.5% | 5,034 |
| February | 85.9% | 4,852 |
| March | 82.4% | 5,939 |
| April | 84.2% | 6,132 |
| May | 79.7% | 6,724 |
| June | 78.6% | 6,282 |
| July | 76.8% | 6,518 |
| August | 84.4% | 6,141 |
| September | 86.8% | 5,993 |
| October | 87.5% | 6,412 |
| November | 86.9% | 5,520 |
| December | 83% | 5,363 |
Airlines at SDF
Every airline with at least 100 departures from SDF, busiest first. These are that airline’s departures from this airport only — its record across the country sits on its own page.
| Airline | Left on time | Typical delay | Cancelled | Departures |
|---|---|---|---|---|
| Republic Airways | 89% | 69 min | 1.8% | 17,713 |
| Southwest Airlines | 82.1% | 57 min | 1.1% | 15,440 |
| American Airlines | 78.8% | 118 min | 2.1% | 7,790 |
| Delta Air Lines | 88.5% | 84 min | 1.2% | 7,570 |
| SkyWest Airlines | 81.9% | 99 min | 1.6% | 5,869 |
| PSA Airlines | 76.9% | 114 min | 3.3% | 5,148 |
| Envoy Air | 81% | 67 min | 1.5% | 3,752 |
| United Airlines | 83.5% | 81 min | 0.9% | 2,584 |
| Spirit Airlines | 71.4% | 72 min | 1.9% | 2,458 |
| Allegiant Air | 72.2% | 98 min | 1.2% | 2,159 |
| Endeavor Air | 85.3% | 80 min | 1.2% | 427 |
What delays out of SDF were put down to
Airlines file a reason with every arrival running 15 minutes late or more. Across 12,434 flights that departed SDF and ran 15 minutes late or more, the delay minutes break down with 37% put down to airline operations and 35.4% to late-arriving aircraft.
- Late-arriving aircraft 35.4%
- Airline operations 37%
- Air traffic & airport volume 22.1%
- Severe weather 5.3%
- Security 0.2%
Late-arriving aircraft is the knock-on category: the plane came in late, so it went out late again. It is why a 7am problem in Newark is still a problem in Denver at dinnertime, and why it is usually the biggest slice on the bar.
If you are connecting through SDF
Of 70,908 scheduled arrivals into SDF, 77.4% reached the gate less than 15 minutes behind schedule. Of the 14,742 arrivals that ran late, 53.7% were no more than 45 minutes behind — which is the difference between a tight connection and a new boarding pass.
Work out a specific layover — pick the airport and the minutes you have, and the tool reads the same arrival records back as a share.
Busiest routes out of SDF
Ranked by flights, with the share that arrived on time at the far end. Where a route carries enough flights for a page of its own the chip goes there; otherwise it goes to the destination airport.
- ATL 89.1% on time · 8,428 flights
- ORD 80.6% on time · 7,044 flights
- DFW 75.7% on time · 6,221 flights
- CLT 77% on time · 5,604 flights
- LGA 86.3% on time · 4,185 flights
- DTW 85.6% on time · 3,519 flights
- DEN 83.3% on time · 3,273 flights
- DCA 79.8% on time · 3,089 flights
- MDW 86% on time · 3,073 flights
- EWR 88.2% on time · 2,950 flights
SDF in one number
Louisville Muhammad Ali (SDF)
Rank 60 of 363 US airports by departures. Steadiest stretch of the day: Before 6am. Hardest month: July.
Questions about SDF
- What is the best time of day to fly out of Louisville Muhammad Ali?
- Before 6am. Departures in that band left on time 92.8% of the time across 2,128 flights, July 2023 through June 2026 — the best of the ten bands in the day. The 8–10pm band was the weakest at 66.1%.
- Is the early flight out of SDF really more reliable?
- 6–8am departures from SDF left on time 91.1% of the time across 17,252 flights; 6–8pm departures, 71.9% across 6,938. That is a gap of 19.2 points, and it is the whole case for the early flight.
- What is the worst month to fly out of SDF?
- July: 76.8% of the departures that flew left on time, with 6,518 scheduled. October was the other end of the year at 87.5%. Each figure pools three years of that calendar month.
- Which airline is most on time at SDF?
- Republic Airways — 89% of its 17,713 departures from SDF left on time. Spirit Airlines sat at the other end at 71.4% over 2,458 flights. Only airlines with at least 100 departures here are ranked.
- How often are flights cancelled at SDF?
- 1.6% of scheduled departures were cancelled over July 2023 through June 2026. Cancellations are counted against everything scheduled, not against everything that flew — a rate that looks small still adds up to real people in a rebooking line.