Carrier route record

OOORD→STL

SkyWest Airlines · Chicago to St. Louis

Flights: 834
Period: July 2025 to June 2026
Share of route: 27%
Carriers: 5

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with SkyWest Airlines.

SkyWest on ORD to STL carries a cancellation problem, not just a delay problem: 4.2% of scheduled flights never operate, against 1.8% nationally. Of the ones that do fly, about seven flights in ten arrive on time, worth a C− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 834 flights. The strongest carrier on the route with a full sample, Republic Airways, flew 444 at 76.2% on time.

Republic Airways is the most reliable of the four carriers covered here at 76.2% on time across 444 flights.

On time

68.2%

Arrivals under 15 minutes late, of 795 completed flights

Avg delay

73 min

Across delayed arrivals only, not all flights

Cancelled

4.20%

National rate is 1.81%

Whole route

71.0%

Every carrier on ORD to STL, 3,068 flights

These figures cover 834 flights between July 2025 and June 2026. Beyond the headline rate, 14.1% 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.

Carrier by carrier

SkyWest against every carrier on ORD to STL

SkyWest flew 834 of the 3,068 flights on ORD to STL, about 27% of it. Its 68.2% on time is 3 points worse than the route as a whole, which runs 71.0%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from Republic at 76.2% to American at 65.6%.

The choice of carrier is not cosmetic here. Republic Airways arrives on time 76.2% of the time; American Airlines manages 65.6%. Sample sizes sit next to every figure, because a two-point gap across 535 flights means less than a ten-point one.

On-time performance by carrier on ORD to STL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airways	444	76.2%	77 min	2.48%	B
Envoy Air	727	75.0%	52 min	2.34%	B
United Airlines	528	71.2%	79 min	1.33%	C
SkyWest Airlines (this page)	834	68.2%	73 min	4.20%	C−
American Airlines	535	65.6%	86 min	2.62%	C

Republic leads American by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When SkyWest runs best on this route

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. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am145 flights75.2%
8am–11am84 flights68.3%
11am–2pm275 flights71.7%
2pm–5pm149 flights67.4%
5pm–8pm180 flights57.0%
8pm–5am1 flights—

Scale runs 50% to 80%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 57.0% on time, against 75.2% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 11am–2pm window is the busiest, with 275 flights scheduled in it.

Across the year

SkyWest on ORD to STL through the year

Darker means more delays. Figures are on-time percentages.September best, December worst

December is the weak month at 47.8% on time, against 88.0% in September. 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 96 flights.

Across the week, Wednesday is the strongest day at 72.6% on time and Monday the weakest at 61.6%. 11 points is a smaller lever than departure hour, but it is free.

Delay causes

Why SkyWest runs late on this route

One category carries most of the weight here. Carrier accounts for 48% of the 19,000 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.

Carrier
48%
Late-arriving aircraft
22%
Extreme weather
19%
National Airspace System
11%

Extreme weather accounts for 19% 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 18,539 reported delay minutes.

The largest share of delay minutes, 48%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 8,973 of the 19,000 delay minutes reported here.

Cancellations run at 4.20%, 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 stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 14.1% 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.

At 258 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 5am–8am window matters as much as it does.

The return leg is a different operation and performs like one: it runs 62.8% on time across 836 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. 834 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 SkyWest on ORD to STL

Put together: the delay figures matter less here than the 4.20% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 795 completed flights over 12 months sit behind that.

Where to go next

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