Route reliability record
SDF→ATL
Louisville to Atlanta
- Flights
- 2,710
- Period
- September 2025 to August 2026
- Distance
- 321 mi
- Carriers
- 1
This route earns an A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 12 points better than the national rate of 77.3%. When something does go wrong the average delay runs an hour and a half. That rests on 2,710 SDF to ATL flights, with a median arrival 18 minutes early.
Best time to fly SDF to ATL: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 92.3% of the time and Wednesday flights 93.7%, against 89.6% for the route overall.
Set against the rest of the country, this route's record is 12 points better than the US average of 77.3%. That gap is worth roughly 123 fewer late arrivals for every thousand flights.
Key figures
On time
89.6%
Arrivals under 15 minutes late, of 2,663 completed flights
Avg delay
89 min
Across delayed arrivals only, not all flights
Cancelled
1.55%
National rate is 1.89%
Best carrier
Delta
89.6% on time across 2,710 flights
These figures cover 2,710 flights between September 2025 and August 2026. The median arrival is 18 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.
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Carrier by carrier
Which airline is most reliable on SDF to ATL
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 | 89.6% | 89 min | 1.55% | A |
Flight by flight
Flights on SDF to ATL
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.
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Departure window
The best time of day to leave
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 2,710 flights.
- 5am–8am710 flights92.3%
- 8am–11am649 flights91.5%
- 11am–2pm497 flights89.9%
- 2pm–5pm374 flights85.8%
- 5pm–8pm393 flights84.4%
- 8pm–5am87 flights90.5%
Scale runs 75% to 100%.
The early departures do better, though not dramatically: 92.3% on time for the 5am–8am window against 84.4% for 5pm–8pm. Worth taking if the schedule allows, not worth an extra connection. The 5am–8am window is the busiest, with 710 flights scheduled in it.
Explore
Filter SDF to ATL 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 SDF to ATL, the best departure window is 5am–8am at 92.3% on time and the worst is 5pm–8pm at 84.4%, a real gap of 7.9 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am92.3%
- 8–11am91.5%
- 11am–2pm89.9%
- 2–5pm85.8%
- 5–8pm84.4%
- 8pm–5am90.5%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 15 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 83.9% on time, 15 points below September, the best at 98.6%. 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 93.7% on time and Sunday the weakest at 85.0%, a spread of 9 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 25,000 reported delay minutes.
- 35%Late-arriving aircraft
- 34%Carrier
- 23%National Airspace System
- 8%Extreme weather
35% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 25,000 reported delay minutes here, that single category outweighs weather by 5 to one. The split is drawn from 24,850 reported delay minutes.
The largest share of delay minutes, 34%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 8,504 of the 25,000 delay minutes reported here.
Cancellations sit at 1.55% against a national 1.89%, which is ordinary. Diversions add another 0.18%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.7% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 84.3% on time across 2,710 flights, 5 points below 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 ATL 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 98.6% on time and July 83.9%, a swing of 15 points. If the dates move at all, move them out of July before you think about anything else. 2,663 completed flights over 12 months sit behind that.
Common questions
SDF to ATL questions
How often is SDF to ATL delayed?
About one flight in ten arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 10.4% of the 2,710 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
How reliable is SDF to ATL compared with the rest of the country?
89.6% of flights arrive on time here against a national 77.3%, a difference of 12 points in its favour. That is worth a A on this site's grading scale.
What time of day has the fewest delays on SDF to ATL?
The 5am–8am departure window is the strongest at 92.3% on time. The 5pm–8pm window is the weakest at 84.4%, 8 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 SDF to ATL?
July is the weakest month at 83.9% on time, compared with 98.6% in September. Across the year that is 15 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
- ATL to SDF — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- SDF to ORD, a related route79.3%
- LGA to ATL, a related route75.5%
- SDF to DFW, a related route76.0%
- Delta Air Lines on-time record89.6%
- The most punctual routes in the US, and the least
- Why the first flight of the morning is statistically safest
Direction matters. SDF to ATL and ATL to SDF are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.