Route reliability record
ATL→SDF
Atlanta to Louisville
- Flights
- 2,710
- Period
- September 2025 to August 2026
- Distance
- 321 mi
- Carriers
- 1
This route earns a B. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 2,710 ATL to SDF flights, with a median arrival 8 minutes early.
Best time to fly ATL to SDF: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 91.0% of the time and Wednesday flights 89.4%, against 84.3% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.3%. That gap is worth roughly 70 fewer late arrivals for every thousand flights.
Key figures
On time
84.3%
Arrivals under 15 minutes late, of 2,667 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
1.48%
National rate is 1.89%
Best carrier
Delta
84.3% on time across 2,710 flights
These figures cover 2,710 flights between September 2025 and August 2026. The median arrival is 8 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Which airline is most reliable on ATL to SDF
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 2,710 | 84.3% | 64 min | 1.48% | B |
Flight by flight
Flights on ATL to SDF
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 11 points, against half a point between the best and worst carrier.
- 5am–8am105 flights91.0%
- 8am–11am658 flights89.2%
- 11am–2pm362 flights87.2%
- 2pm–5pm430 flights79.6%
- 5pm–8pm440 flights81.8%
- 8pm–5am715 flights81.6%
Scale runs 70% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.0% of the time, against 79.6% for the afternoon window. That is 11 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 715 flights scheduled in it.
Explore
Filter ATL to SDF by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On ATL to SDF, the best departure window is 5am–8am at 91.0% on time and the worst is 2pm–5pm at 79.6%, a wide gap of 11.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am91.0%
- 8–11am89.2%
- 11am–2pm87.2%
- 2–5pm79.6%
- 5–8pm81.8%
- 8pm–5am81.6%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 21 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 73.2% on time, 21 points below September, the best at 93.7%. 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 263 flights.
Across the week, Wednesday is the strongest day at 89.4% on time and Sunday the weakest at 76.2%, a spread of 13 points.
Delay causes
Why this route gets delayed
Carrier accounts for 47% of the 27,000 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Carrier
- 26%Late-arriving aircraft
- 20%National Airspace System
- 7%Extreme weather
- 0%Security
The largest share of delay minutes, 47%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 12,000 of the 27,000 delay minutes reported here. The split is drawn from 26,657 reported delay minutes.
Cancellations sit at 1.48% against a national 1.89%, which is ordinary. Diversions add another 0.11%.
Connections and stage length
What a delay here actually costs
5.1% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
At 321 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 89.6% on time across 2,710 flights, 5 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 5 points of difference.
The sample behind these figures is 2,710 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.
Work out the risk of missing a connection in SDF after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 93.7% on time and July 73.2%, a swing of 21 points. If the dates move at all, move them out of July before you think about anything else. 2,667 completed flights over 12 months sit behind that.
Common questions
ATL to SDF questions
How often is ATL to SDF delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 15.7% of the 2,710 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is ATL to SDF compared with the rest of the country?
84.3% of flights arrive on time here against a national 77.3%, a difference of 7 points in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on ATL to SDF?
The 5am–8am departure window is the strongest at 91.0% on time. The 2pm–5pm window is the weakest at 79.6%, 11 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 ATL to SDF?
July is the weakest month at 73.2% on time, compared with 93.7% in September. Across the year that is 21 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 ATL — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- ATL to LGA, a related route72.3%
- ORD to SDF, a related route75.8%
- ATL to MCO, a related route70.3%
- Delta Air Lines on-time record84.3%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. ATL to SDF and SDF to ATL are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Embed ATL to SDF’s on-time badge on your site
Paste this into a web page. The badge shows the current on-time rate, cancellation rate and grade, and updates every month. Preview it, or build a badge for another route or airport.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.