Best Time to Fly IAD to SDF: On-Time Stats by Hour & Airline
Washington Dulles International → Louisville Muhammad Ali International
Data through July 2026 · Last updated October 18, 2026
236 flights were scheduled from Washington (IAD) to Louisville (SDF) in the last 12 months, and 86.6% of those that flew arrived on time, 9.0 points above the US average of 77.6%.
Republic Airways was the only reporting airline with regular flights on this route.
September has been the best month (96% on time) and Sunday the weakest day of the week (84%).
1.7% of flights were cancelled, versus 1.8% nationally.
IAD to SDF on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| Republic Airways | 86.9% | 134 min | 1.7% | 234 |
| United Airlines | Limited data | 2 | ||
80%+ good 70–79.9% fair <70% poor
Best time of day to fly IAD to SDF
On-time arrival % by scheduled departure hour (local time), 800 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 8am–9am | 88.5% | 0.6% | 335 |
| 9am–10am | Limited data | 15 | |
| 12pm–1pm | Limited data | 4 | |
| 3pm–4pm | 91.1% | 0.0% | 79 |
| 5pm–6pm | 87.4% | 1.8% | 227 |
| 6pm–7pm | 90.2% | 3.5% | 116 |
| 10pm–11pm | Limited data | 24 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on IAD to SDF
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | Limited data | 14 | ||
| Christmas & New Year (Dec 20 - Jan 3) | Limited data | 15 | ||
| Summer peak (Jun 15 - Aug 15) | 81.7% | -8.3 pts | 2.6% | 226 |
| All other days | 90.0% | — | 0.9% | 545 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).