Flight number record

OO 4740

SkyWest Airlines · Milwaukee to Chicago

Route: MKE → ORD
Departs: 12:05
Flights: 336
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 D−. 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 336 flights, with a median arrival 5 minutes late.

The national on-time rate over the same period is 77.6%, so OO 4740 runs 13 points behind the country as a whole. Across a thousand flights that is about 127 extra late arrivals.

On time

64.9%

Arrivals under 15 minutes late, of 322 completed flights

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

4.17%

National rate is 1.81%

1 hour+ late

14.9%

National rate is 8.1%

These figures cover 336 flights between July 2025 and June 2026. Beyond the headline rate, 14.9% 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 OO 4740 flies

OO 4740 flies MKE to ORD without a single fixed slot. Its most common scheduled departure was 12:05, used on 104 of 336 flights, with 11:30 (82 flights) and 12:10 (49 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 12:05104 flights31.0%
Departs 11:3082 flights24.4%
Departs 12:1049 flights14.6%

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 12:05 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and OO 4740 runs 14 points worse at 64.9%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

OO 4740 next to MKE to ORD

Every carrier on MKE to ORD combined arrived on time 67.4% of the time across 5,202 flights, so OO 4740 is 3 points behind it. SkyWest flew 4,932 flights on the same city pair under all its flight numbers, including this one, and those ran 67.3% on time. Across its whole network SkyWest Airlines managed 79.0%, which this flight trails by 14 points.

OO 4740 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
OO 4740thin sample	336	64.9%	71 min	4.17%	D−
All SkyWest Airlines on MKE–ORD	4,932	67.3%	94 min	4.12%	C−
All carriers on MKE–ORD	5,202	67.4%	94 min	4.33%	C−
SkyWest Airlines, whole network	852,935	79.0%	88 min	1.77%	B

Across the year

OO 4740 quarter by quarter

Quarter by quarter OO 4740 held fairly steady: 64.4% in Jul–Sep 2025, 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 202592 flights64.4%
Oct–Dec 202591 flights65.1%
Jan–Mar 202690 flights67.4%
Apr–Jun 202663 flights61.7%

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

By weekday, OO 4740 did best on Tuesday at 76.6% on time and worst on Sunday at 54.5%. Each day rests on about 48 flights, so a gap of 22 points is worth noticing but could still narrow in another year.

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 7,985 reported delay minutes.

Late-arriving aircraft
32%
National Airspace System
28%
Carrier
25%
Extreme weather
15%

Extreme weather accounts for 15% 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 2.4 times the usual weather exposure. The split is drawn from 7,985 delay minutes reported on OO 4740.

Cancellations run at 4.17%, 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 14.9% 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 DEN to ACV (21), ROC to ORD (1) and CLT 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. 336 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: 4.17% of its 336 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures