Route reliability record
SDF→DTW
Louisville to Detroit
- Flights
- 1,089
- Period
- September 2025 to August 2026
- Distance
- 306 mi
- Carriers
- 3
This route lands a B, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That rests on 1,089 SDF to DTW flights, of which Republic Airways flew 408 at 89.9% on time.
Best time to fly SDF to DTW: a 8am–11am departure, ideally on a Wednesday. Flights in that window arrived on time 87.9% of the time and Wednesday flights 87.6%, against 82.7% for the route overall.
Set against the rest of the country, this route's record is 5 points better than the US average of 77.3%. That gap is worth roughly 54 fewer late arrivals for every thousand flights.
Key figures
On time
82.7%
Arrivals under 15 minutes late, of 1,078 completed flights
Avg delay
121 min
Across delayed arrivals only, not all flights
Cancelled
1.01%
National rate is 1.89%
Best carrier
Republic
89.9% on time across 408 flights
These figures cover 1,089 flights between September 2025 and August 2026. Beyond the headline rate, 8.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on SDF to DTW
The choice of carrier is not cosmetic here. Republic Airways arrives on time 89.9% of the time; SkyWest Airlines manages 78.6%. Sample sizes sit next to every figure, because a two-point gap across 670 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airways | 408 | 89.9% | 77 min | 0.25% | A+ |
| SkyWest Airlines | 670 | 78.6% | 134 min | 1.49% | B |
| Delta Air Linesthin sample | 11 | 63.6% | 114 min | 0.00% | D+ |
Republic leads SkyWest by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on SDF to DTW
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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Best ways to make this trip
The most reliable ways to fly Louisville to Detroit
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SDF → DTWLouisville to Detroit | Republic Airways | 89.7% | 89.9% | 0.25% | 5pm–8pm, Thu | YX 5824 07:50 |
| 2. SDF → DTWLouisville to Detroit | SkyWest Airlines | 77.4% | 78.6% | 1.49% | 8am–11am, Sat | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 18 points, against 11 points between the best and worst carrier.
- 5am–8am79 flights84.8%
- 8am–11am624 flights87.9%
- 11am–2pm11 flights—
- 2pm–5pm189 flights77.4%
- 5pm–8pm186 flights69.9%
- 8pm–5am—
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 87.9% of the time, against 69.9% for the evening window. That is 18 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 624 flights scheduled in it.
Explore
Filter SDF to DTW 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 DTW, the best departure window is 8am–11am at 87.9% on time and the worst is 5pm–8pm at 69.9%, a wide gap of 18.0 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am84.8%
- 8–11am87.9%
- 11am–2pm—
- 2–5pm77.4%
- 5–8pm69.9%
- 8pm–5am—
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 30 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.
December is the weak month at 64.4% on time, against 94.3% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. May was the busiest month here, with 118 flights.
Across the week, Wednesday is the strongest day at 87.6% on time and Friday the weakest at 75.3%, a spread of 12 points.
Delay causes
Why this route gets delayed
Carrier accounts for 69% of the 22,000 delay minutes carriers reported here, and the remaining four split what is left.
- 69%Carrier
- 18%Extreme weather
- 9%National Airspace System
- 3%Late-arriving aircraft
Extreme weather accounts for 18% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.0 times the usual weather exposure. The split is drawn from 22,493 reported delay minutes.
The largest share of delay minutes, 69%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 16,000 of the 22,000 delay minutes reported here.
Cancellations sit at 1.01% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here actually costs
8.6% 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 close to two hours, which a normal layover absorbs.
At 306 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 8am–11am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 77.5% on time across 1,089 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.
One caution: this is a thin sample. 1,089 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
Work out the risk of missing a connection in DTW after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,089 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 82.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,078 completed flights over 12 months sit behind that.
Common questions
SDF to DTW questions
How often is SDF to DTW 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 17.3% of the 1,089 flights in this analysis, against 22.7% nationally. Delayed flights are late by close to two hours on average.
Which airline is most reliable on SDF to DTW?
Republic Airways leads at 89.9% on time across 408 flights. SkyWest Airlines is at the other end on 78.6%, a gap of 11 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SDF to DTW?
The 8am–11am departure window is the strongest at 87.9% on time. The 5pm–8pm window is the weakest at 69.9%, 18 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 December delays on SDF to DTW?
December is the weakest month at 64.4% on time, compared with 94.3% in October. Across the year that is 30 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
- DTW to SDF — the return legseparate record
- Detroit Metropolitan Wayne County (DTW) delay statistics
- Republic Airways on SDF to DTW89.9%
- SkyWest Airlines on SDF to DTW78.6%
- SDF to ORD, a related route79.3%
- ORD to DTW, a related route71.1%
- SDF to ATL, a related route89.6%
- Republic Airways on-time record89.9%
- SkyWest Airlines on-time record78.6%
- Delta Air Lines on-time record63.6%
- Same route, different airline: where the carrier you pick matters most
- The best time of day to fly, according to 7.05 million flight records
Direction matters. SDF to DTW and DTW 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.