Flight number record
YX 3598
Republic Airways · Chicago to Louisville
- Route
- ORD → SDF
- Departs
- 17:50
- Flights
- 348
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s YX 3598, check with Republic Airways. Republic Airways flies under contract for larger airlines, so a ticket for this flight may show a different airline code and number.
YX 3598 sits in the middle of the pack with a B−. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 348 flights, with a median arrival 6 minutes early.
Key figures
On time
75.5%
Arrivals under 15 minutes late, of 335 completed flights
Avg delay
76 min
Across delayed arrivals only, not all flights
Cancelled
3.74%
National rate is 1.81%
1 hour+ late
8.1%
National rate is 8.1%
These figures cover 348 flights between July 2025 and June 2026. Beyond the headline rate, 8.1% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When YX 3598 flies
YX 3598 flies ORD to SDF without a single fixed slot. Its most common scheduled departure was 17:50, used on 102 of 348 flights, with 17:55 (83 flights) and 17:45 (74 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 17:50102 flights29.3%
- Departs 17:5583 flights23.9%
- Departs 17:4574 flights21.3%
Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 17:50 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and YX 3598 runs 7 points better at 75.5%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
Against the route
YX 3598 next to ORD to SDF
Every carrier on ORD to SDF combined arrived on time 75.3% of the time across 2,804 flights, so YX 3598 is about level with it. Republic flew 1,733 flights on the same city pair under all its flight numbers, including this one, and those ran 75.0% on time. Across its whole network Republic Airways managed 78.5%, which this flight trails by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| YX 3598thin sample | 348 | 75.5% | 76 min | 3.74% | B− |
| All Republic Airways on ORD–SDF | 1,733 | 75.0% | 75 min | 3.87% | B− |
| All carriers on ORD–SDF | 2,804 | 75.3% | 71 min | 3.32% | B− |
| Republic Airways, whole network | 361,482 | 78.5% | 72 min | 4.08% | B− |
Across the year
YX 3598 quarter by quarter
Quarter by quarter YX 3598 held fairly steady: 80.2% in Jul–Sep 2025, 74.6% in Oct–Dec 2025, 72.1% in Jan–Mar 2026 and 74.7% in Apr–Jun 2026. A spread of 8 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202592 flights80.2%
- Oct–Dec 202575 flights74.6%
- Jan–Mar 202690 flights72.1%
- Apr–Jun 202691 flights74.7%
Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, YX 3598 ranged from 70.8% on Sunday to 82.6% on Thursday. With about 50 flights behind each day, a spread of 12 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why YX 3598 runs late
One category carries most of the weight here. Late-arriving aircraft accounts for 44% of the 6,253 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 44%Late-arriving aircraft
- 39%Carrier
- 16%National Airspace System
- 1%Extreme weather
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 6,253 reported delay minutes here, that single category outweighs weather by 44 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 6,253 delay minutes reported on YX 3598.
Cancellations run at 3.74%, against 1.81% nationally. That is about one flight in 25 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and routes
What a delay on this flight costs
8.1% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
The same number turns up on three other city pairs in the data, including BHM to ORD (20), STL to ORD (16) and ORD to STL (6), but none flew often enough under YX 3598 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ORD to SDF only.
One caution: this is a thin sample. 348 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.
What to do with this
Booking YX 3598
For a booking, the cancellation rate is the figure to plan around on YX 3598: 3.74% of its 348 scheduled flights did not operate. A late arrival costs a little over an hour, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- ORD to SDF, every carrier and departure
- SDF to ORD, the return direction
- Republic Airways 3551 on the same route74.4%
- Republic Airways 4603 on the same route71.3%
- Chicago O'Hare International (ORD) delay statistics
- Republic Airways on-time record
- Every Republic Airways flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
A flight number here means Republic Airways’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.