Flight number record

YX 4603

Republic Airways · Chicago to Louisville

Route: ORD → SDF
Departs: 20:20
Flights: 258
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 C−. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 258 flights, with a median arrival 10 minutes early.

The national on-time rate over the same period is 77.6%, so YX 4603 runs 6 points behind the country as a whole. Across a thousand flights that is about 63 extra late arrivals.

On time

71.3%

Arrivals under 15 minutes late, of 244 completed flights

Avg delay

79 min

Across delayed arrivals only, not all flights

Cancelled

4.65%

National rate is 1.81%

1 hour+ late

14.3%

National rate is 8.1%

These figures cover 258 flights between July 2025 and June 2026. Beyond the headline rate, 14.3% 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 4603 flies

YX 4603 flies ORD to SDF without a single fixed slot. Its most common scheduled departure was 20:20, used on 39 of 258 flights, with 20:49 (32 flights) and 20:27 (31 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 20:2039 flights15.1%
Departs 20:4932 flights12.4%
Departs 20:2731 flights12.0%

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 20:20 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and YX 4603 runs level with that at 71.3%. 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 4603 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 4603 is 4 points behind 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 7 points.

YX 4603 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
YX 4603thin sample	258	71.3%	79 min	4.65%	C−
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 4603 quarter by quarter

Quarter by quarter YX 4603 held fairly steady: 68.6% in Jul–Sep 2025, 73.8% in Oct–Dec 2025, 66.7% in Jan–Mar 2026 and 76.3% in Apr–Jun 2026. A spread of 10 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights68.6%
Oct–Dec 202588 flights73.8%
Jan–Mar 202637 flights66.7%
Apr–Jun 202641 flights76.3%

Scale runs 60% to 80%. Rows with fewer than 30 flights show a dash.

By weekday, YX 4603 did best on Friday at 80.0% on time and worst on Sunday at 62.2%. Each day rests on about 37 flights, so a gap of 18 points is worth noticing but could still narrow in another year.

Delay causes

Why YX 4603 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 69% of the 5,545 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.

Late-arriving aircraft
69%
National Airspace System
14%
Carrier
13%
Extreme weather
4%

69% 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 5,545 reported delay minutes here, that single category outweighs weather by 19 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 5,545 delay minutes reported on YX 4603.

Cancellations run at 4.65%, against 1.81% nationally. That is about one flight in twenty 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 14.3% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum 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: 4.65% of its 258 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.

Where to go next

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.

Key figures