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Route · IAD → SDF · 2020–2025 BTS data

Washington to Louisville

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), IAD to SDF (Washington to Louisville) ranks #3636 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

85.1%
On-time
+6.1 pts
vs US avg
101 min
Delay when late
2,295
Flights
#3636 of 4927
Corpus placement

Cancelled

1.0%

Best Month

Oct 2024 95%

Worst Month

Jul 2025 78%

Distance

451 mi

Carriers

8

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Aug 2025 46 4 0 0 YX
Jul 2025 58 13 0 0 YX
Jun 2025 30 9 0 0 YX
May 2025 34 2 0 0 UA,YX
Apr 2025 50 4 0 0 YX
Mar 2025 57 6 0 0 YX
Jan 2025 31 3 3 0 YX
Dec 2024 33 2 0 0 YX
Nov 2024 60 5 0 0 YX
Oct 2024 61 3 0 0 YX
Sep 2024 60 3 0 0 YX
Aug 2024 62 11 3 0 YX
Jul 2024 62 10 0 0 YX
Jun 2024 60 6 0 0 YX
May 2024 45 5 0 0 YX,UA
Apr 2024 30 5 0 0 YX
Mar 2024 31 3 0 0 YX
Jan 2024 31 6 0 0 YX
Dec 2023 31 3 0 0 YX
Nov 2023 30 0 0 0 YX
Oct 2023 31 5 0 0 YX
Sep 2023 31 5 2 0 YX
Aug 2023 31 3 1 0 YX
Jul 2023 32 11 1 0 YX

IAD–SDF seasonal on-time pattern

Best: November (93.2%) · weakest: July (77.1%)

75%80%85%90%95% JanMarAprMayJunJulAugSepOctNovDec 90.4%

Strongest calendar month

November

93.2% on-time · ~41 flights/mo

Busiest calendar month

July

~50 flights/mo avg

Weakest calendar month

July

77.1% on-time · ~50 flights/mo

Cancellation Rate

1.0%

10 of 1,027 flights

Diversion Rate

0.0%

0 of 1,027 flights

Explore origin & destination

On-time and delay data for the airports this route connects.

IAD - Washington

Full on-time, delay-cause, and seasonal performance for Washington, DC.

IAD on-time profile

SDF - Louisville

Full on-time, delay-cause, and seasonal performance for Louisville, KY.

SDF on-time profile

Compare the two airports

See IAD and SDF side by side on delays, cancellations, and reliability.

Compare IAD vs SDF

Origin-hub reliability standing

Among IAD's stronger departures

IAD → SDF posts a 85.1% on-time rate, landing in the ≥85% band with 14 of 58 BTS-tracked routes leaving Washington. The same hub also shows 42 mid-band and 2 challenged departures · fleet-wide on-time rank #1180 of 4927 (highest on-time = #1).

What the Data Says About IAD to SDF

Washington to Louisville (IAD to SDF) is one of the more dependable pairings in the BTS On-Time Performance dataset: a 85.1% on-time rate across 2,295 flights, with delays that do happen averaging 101.3 minutes. The corridor runs roughly 451 miles and is served by 8 carriers. Over the most recent 24 months, 10 of 1,027 flights were cancelled (1.0%) and 0 diverted (0.0%).

The monthly split is wide on this route: Oct 2024 posted the strongest performance at 95% on-time, while Jul 2025 came in at just 78% - a 18-point swing worth factoring into travel timing.

On the multi-year calendar, IAD–SDF peaks in November at 93.2% on-time while July carries the heaviest traffic (~50 flights per month) ; the softest month is July at 77.1%, a 16.1-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does IAD to SDF rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, IAD to SDF ranks #3636 of 4927 tracked domestic routes by total flights (most flights = #1). That ordinal matches our busiest-routes listing (total_flights DESC). See /methodology#corpus-placement for the exact sort basis.
How often are flights delayed from IAD to SDF? ▼
Flights from Washington to Louisville have a 85.1% on-time rate based on 2,295 flights. The average delay is 101.3 minutes. The best recent month was Oct 2024 with 95% on-time.
What is the cancellation rate for IAD to SDF? ▼
Over the last 24 months, 1.0% of flights on this route were cancelled (10 of 1,027 flights) and 0.0% were diverted.
How far is the flight from IAD to SDF? ▼
The flight distance from Washington (IAD) to Louisville (SDF) is approximately 451 miles. This route is served by 8 carriers.
When is the best time to fly from IAD to SDF? ▼
The best recent month for on-time performance was Oct 2024 (95% on-time). The worst was Jul 2025 (78% on-time). Consider booking during months with historically better performance.

Airports on this route

IAD Airport

Washington
SDF Airport

Louisville
Data source

Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data. Statistics reflect cumulative performance across all available reporting periods.

Read our methodology - how this data is sourced, computed, and verified.

Using IAD–SDF data

IAD–SDF runs 6.1 pts above the national 79% average; the remaining risk is month-to-month swing and carrier mix, not a weak headline rate.

  • Compare IAD and SDF airport profiles: delay causes and top routes differ even on the same corridor. IAD airport
  • If your dates flex, November (93.2% on-time) beats July (77.1%) on this corridor. Seasonal chart
  • 4 other routes post a similar 85.1% on-time rate; compare before you commit to this pairing. Similar routes

On-time rate reflects the BTS historical average across all reporting carriers on this origin–destination pair, not any single flight or booking recommendation.

Data sourced from U.S. Department of Transportation Bureau of Transportation Statistics (BTS) On-Time Performance data. See our methodology for details. Retrieved and formatted by PlainFlights

Every figure on PlainFlights is rendered directly from BTS On-Time Performance data, no number is typed in by an editor. This page aggregates this specific route's on-time performance and monthly trend, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.