83% of flights from Boston to Louisville arrived on time over the past 12 months. That is better than the typical U.S. route. The 10 a.m. departures ran on time 88% of the time; the 1 p.m. ones 79%. Most reliable airline: American Airlines (84%). 6% of flights arrived more than an hour late or not at all.
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for BOS → SDF: when a flight was late, it was under 45 minutes late 57% of the time. About 1 in 24 flights landed an hour or more late, and 1 in 355 three hours or more; 1.7% were cancelled outright.
- On time or early83%
- 15–30 min late5.8%
- 30–60 min late4.9%
- 1–2 hours late3.1%
- 2–3 hours late0.7%
- 3+ hours late0.3%
- Diverted0.1%
- Cancelled1.7%
Share of all 709 scheduled flights, past 12 months, by arrival time against schedule.
By airline
| Airline | Flights | On time | Cancelled | Typical arrival | 1h+ late | Avg when late | Operated by |
|---|---|---|---|---|---|---|---|
| American Airlines | 360 | 84% | 1.7% | −10 min | 4.4% | +57 min | Envoy 62%, Republic Airways 38% |
| Delta Air Lines | 349 | 83% | 1.7% | −12 min | 3.7% | +49 min | Republic Airways 99%, Delta Air Lines 1% |
Airline = the name on the ticket. Regional flights (e.g. "Delta Connection") count under the ticketing airline, and the operator is listed.
Best time of day to fly
On-time rate by scheduled departure hour (local time at BOS). Delays build through the day as late planes knock on, so early flights usually do best.
By airline and hour
| Departs | American Airlines | Delta Air Lines |
|---|---|---|
| 9 a.m. | — | 83% |
| 10 a.m. | 88% | — |
By month
Each calendar month pooled over 2023–2026. Best: November (95%). Worst: January (77%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 106 | 85% | 5.7% |
| Tuesday | 104 | 81% | 3.9% |
| Wednesday | 102 | 89% | 0.0% |
| Thursday | 101 | 84% | 0.0% |
| Friday | 103 | 83% | 0.0% |
| Saturday | 90 | — | — |
| Sunday | 103 | 80% | 1.0% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 7 · airline 3 · air traffic/airport 2
Month by month
Not enough months with data to draw a trend.
Flight numbers on this route
Regular flights with at least 120 scheduled trips in the past year. Sorted by departure time.
| Flight | Departs | Flights | On time | Cancelled | Typical arrival | Operated by |
|---|---|---|---|---|---|---|
| DL 5615 | 9:55 a.m. | 234 | 83% | 2.6% | −11 min | Republic Airways |
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| May 3, 2026 | 4 | 25% | 0 |
| Apr 30, 2026 | 4 | 25% | 0 |
Questions
How often are flights from BOS to SDF on time?
83% of 709 scheduled flights from Boston, MA to Louisville, KY arrived within 15 minutes of schedule between September 2025 and August 2026. 1.7% were cancelled.
What is the best time of day to fly BOS to SDF?
Flights scheduled to leave at 10 a.m. were the most reliable (88% on time). The 1 p.m. departures were the least (79%).
Which airline is most on time from BOS to SDF?
American Airlines: 84% of its 360 flights on the route arrived on time. Delta Air Lines: 83%.
What month has the most delays from BOS to SDF?
January (77% on time). The best month is November (95%), over 2023–2026.
Related
- SDF → BOS (return)
- Boston Logan (BOS) delays by hour
- Flights into Louisville Muhammad Ali (SDF)
- American Airlines on-time record
- Delta Air Lines on-time record
- Connecting off this flight? Check the risk
Domestic flights by the airlines that report to the U.S. DOT, plus their regional partners. "On time" means arriving less than 15 minutes after schedule; cancelled and diverted flights count as not on time. Past performance is a guide, not a forecast. Method.