Flight number record

OO 4740

SkyWest Airlines · Milwaukee to Chicago

Route: MKE → ORD
Departs: 12:05
Flights: 294
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s OO 4740, check with SkyWest Airlines. SkyWest Airlines flies under contract for larger airlines, so a ticket for this flight may show a different airline code and number.

OO 4740 draws a C−. About one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 294 flights, with a median arrival 3 minutes late.

The national on-time rate over the same period is 77.3%, so OO 4740 runs 10 points behind the country as a whole. Across a thousand flights that is about 100 extra late arrivals.

On time

67.3%

Arrivals under 15 minutes late, of 281 completed flights

Avg delay

75 min

Across delayed arrivals only, not all flights

Cancelled

4.42%

National rate is 1.89%

1 hour+ late

13.5%

National rate is 8.3%

These figures cover 294 flights between September 2025 and August 2026. Beyond the headline rate, 13.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Schedule

When OO 4740 flies

OO 4740 flies MKE to ORD without a single fixed slot. Its most common scheduled departure was 12:05, used on 91 of 294 flights, with 11:30 (82 flights) and 10:45 (32 flights) next.

Departs 12:0591 flights31.0%
Departs 11:3082 flights27.9%
Departs 10:4532 flights10.9%

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 12:05 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and OO 4740 runs 11 points worse at 67.3%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

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Against the route

OO 4740 next to MKE to ORD

Every carrier on MKE to ORD combined arrived on time 68.4% of the time across 5,344 flights, so OO 4740 is about level with it. SkyWest flew 5,046 flights on the same city pair under all its flight numbers, including this one, and those ran 68.3% on time. Across its whole network SkyWest Airlines managed 78.7%, which this flight trails by 11 points.

OO 4740 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
OO 4740thin sample	294	67.3%	75 min	4.42%	C−
All SkyWest Airlines on MKE–ORD	5,046	68.3%	94 min	4.22%	C−
All carriers on MKE–ORD	5,344	68.4%	93 min	4.38%	C−
SkyWest Airlines, whole network	855,406	78.7%	88 min	1.79%	B

Across the year

OO 4740 quarter by quarter

Quarter by quarter OO 4740 held fairly steady: 65.1% in Oct–Dec 2025, 67.4% in Jan–Mar 2026 and 61.7% in Apr–Jun 2026. A spread of 6 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202530 flights—
Oct–Dec 202591 flights65.1%
Jan–Mar 202690 flights67.4%
Apr–Jun 202663 flights61.7%
Jul–Sep 202620 flights—

Scale runs 55% to 75%. Rows with fewer than 30 flights show a dash.

By weekday, OO 4740 did best on Tuesday at 77.5% on time and worst on Sunday at 55.3%. Each day rests on about 42 flights, so a gap of 22 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late OO 4740 runs when it is late

The 92 late arrivals split 35 under half an hour, 19 between 30 and 60 minutes, and 38 an hour or more.

15+ min early44 flights15.7%
Within 15 min145 flights51.6%
15–29 min late35 flights12.5%
30–59 min late19 flights6.8%
1–2 hours late19 flights6.8%
2+ hours late19 flights6.8%

Scale runs 0% to 100%.

Share of 281 completed flights by arrival against schedule.

Time lost at the gate mostly stays lost. Of 74 departures that left 15 minutes late or more, only 4 made it up before arrival. In the other direction, 22 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at ORD.

The worst days

Worst days for OO 4740

The latest arrival of the period was on 13 March 2026, 6 hours 33 minutes behind schedule; most of its delay minutes were filed as extreme weather. The five worst days are spread across March, December, October and April, with no single month standing out.

The latest arrivals of OO 4740 in the period
Date	Arrived late by	Largest filed cause
13 March 2026	6 hours 33 minutes	Extreme weather
28 December 2025	5 hours 36 minutes	National Airspace System
4 October 2025	5 hours 9 minutes	Carrier
16 March 2026	3 hours 57 minutes	Late-arriving aircraft
16 April 2026	3 hours 56 minutes	Extreme weather

Delay causes

Why OO 4740 runs late

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 6,919 reported delay minutes.

National Airspace System
32%
Late-arriving aircraft
27%
Carrier
25%
Extreme weather
16%

Extreme weather accounts for 16% 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 quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.6 times the usual weather exposure. The split is drawn from 6,919 delay minutes reported on OO 4740.

Cancellations run at 4.42%, against 1.89% nationally. That is roughly 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

13.5% 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 five other city pairs in the data, including ORD to MSN (40), DEN to ACV (21) and BUF to ORD (1), but none flew often enough under OO 4740 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to MKE to ORD only.

One caution: this is a thin sample. 294 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 OO 4740

For a booking, the cancellation rate is the figure to plan around on OO 4740: 4.42% of its 294 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 SkyWest Airlines’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 22 October 2026; recomputed monthly. How this data is collected.

Key figures