Flight number record
YX 4603
Republic Airways · Chicago to Louisville
- Route
- ORD → SDF
- Departs
- 19:29
- Flights
- 258
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s YX 4603, 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 4603 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 77.3%. The late ones land an hour and a half behind schedule. That rests on 258 flights, with a median arrival 12 minutes early.
Key figures
On time
75.3%
Arrivals under 15 minutes late, of 247 completed flights
Avg delay
90 min
Across delayed arrivals only, not all flights
Cancelled
3.88%
National rate is 1.89%
1 hour+ late
15.0%
National rate is 8.3%
These figures cover 258 flights between September 2025 and August 2026. Beyond the headline rate, 15.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When YX 4603 flies
YX 4603 flies ORD to SDF without a single fixed slot. Its most common scheduled departure was 19:29, used on 35 of 258 flights, with 20:49 (32 flights) and 20:25 (30 flights) next.
- Departs 19:2935 flights13.6%
- Departs 20:4932 flights12.4%
- Departs 20:2530 flights11.6%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 19:29 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and YX 4603 runs 7 points better at 75.3%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
YX 4603 next to ORD to SDF
Every carrier on ORD to SDF combined arrived on time 75.8% of the time across 2,792 flights, so YX 4603 is about level with it. Republic flew 1,850 flights on the same city pair under all its flight numbers, including this one, and those ran 75.8% on time. Across its whole network Republic Airways managed 78.1%, which this flight trails by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| YX 4603thin sample | 258 | 75.3% | 90 min | 3.88% | B− |
| All Republic Airways on ORD–SDF | 1,850 | 75.8% | 77 min | 4.11% | B− |
| All carriers on ORD–SDF | 2,792 | 75.8% | 71 min | 3.58% | B− |
| Republic Airways, whole network | 364,452 | 78.1% | 74 min | 4.55% | B− |
Across the year
YX 4603 quarter by quarter
YX 4603 did not run the same all year. Its best quarter was Jul–Sep 2025 at 83.3% on time and its weakest Jan–Mar 2026 at 66.7%, a swing of 17 points on roughly 52 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights83.3%
- Oct–Dec 202588 flights73.8%
- Jan–Mar 202637 flights66.7%
- Apr–Jun 202641 flights76.3%
- Jul–Sep 202662 flights78.0%
Scale runs 60% to 90%.
By weekday, YX 4603 did best on Thursday at 82.9% on time and worst on Sunday at 62.2%. Each day rests on about 37 flights, so a gap of 21 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late YX 4603 runs when it is late
YX 4603 often beats the schedule: 114 of 247 completed flights, 46%, arrived 15 minutes or more early. When YX 4603 is late it tends to be very late: 37 of its 61 late arrivals were an hour or more behind, and 13 were two hours or more.
- 15+ min early114 flights46.2%
- Within 15 min72 flights29.1%
- 15–29 min late10 flights4.0%
- 30–59 min late14 flights5.7%
- 1–2 hours late24 flights9.7%
- 2+ hours late13 flights5.3%
Scale runs 0% to 100%.
Share of 247 completed flights by arrival against schedule.
14 of 70 late departures made up the time and arrived on time, 20% of them. 5 flights left on time and still arrived late.
The worst days
Worst days for YX 4603
The latest arrival of the period was on 3 July 2026, 5 hours 19 minutes behind schedule; most of its delay minutes were filed as extreme weather. On four of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 3 July 2026 | 5 hours 19 minutes | Extreme weather |
| 17 June 2026 | 5 hours 12 minutes | Late-arriving aircraft |
| 24 June 2026 | 5 hours 10 minutes | Late-arriving aircraft |
| 1 December 2025 | 3 hours 56 minutes | Late-arriving aircraft |
| 9 November 2025 | 3 hours 52 minutes | Late-arriving aircraft |
Delay causes
Why YX 4603 runs late
Late-arriving aircraft accounts for 66% of the 5,491 delay minutes carriers reported here, and the remaining four split what is left.
- 66%Late-arriving aircraft
- 15%National Airspace System
- 10%Extreme weather
- 10%Carrier
66% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 5,491 reported delay minutes here, that single category outweighs weather by 7 to one. The split is drawn from 5,491 delay minutes reported on YX 4603.
Cancellations run at 3.88%, against 1.89% 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
15.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The same number turns up on three other city pairs in the data, including BUF to LGA (44), DCA to ORD (24) and CAE to LGA (21), but none flew often enough under YX 4603 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. 258 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 4603
For a booking, the cancellation rate is the figure to plan around on YX 4603: 3.88% of its 258 scheduled flights did not operate. A late arrival costs an hour and a half, 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 3598 on the same route74.2%
- Republic Airways 3551 on the same route76.1%
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.