Flight number record

OO 5555

SkyWest Airlines · Chicago to Milwaukee

Route: ORD → MKE
Departs: 17:50
Flights: 363
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s OO 5555, 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 5555 earns an F−, which is as low as this site's scale goes for a reason. Only 50.1% of flights arrive inside the 15-minute window, 27 points worse than the national rate of 77.6%. Late arrivals average an hour and a half. Treat any tight connection here as a coin flip. That rests on 363 flights, with a median arrival 14 minutes late.

The national on-time rate over the same period is 77.6%, so OO 5555 runs 27 points behind the country as a whole. Across a thousand flights that is about 275 extra late arrivals.

On time

50.1%

Arrivals under 15 minutes late, of 347 completed flights

Avg delay

98 min

Across delayed arrivals only, not all flights

Cancelled

4.13%

National rate is 1.81%

1 hour+ late

23.3%

National rate is 8.1%

These figures cover 363 flights between July 2025 and June 2026. Beyond the headline rate, 23.3% 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 OO 5555 flies

OO 5555 flies ORD to MKE without a single fixed slot. Its most common scheduled departure was 17:50, used on 175 of 363 flights, with 17:45 (117 flights) and 18:10 (49 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 17:50175 flights48.2%
Departs 17:45117 flights32.2%
Departs 18:1049 flights13.5%

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 17:50 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and OO 5555 runs 18 points worse at 50.1%. 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

OO 5555 next to ORD to MKE

Every carrier on ORD to MKE combined arrived on time 64.1% of the time across 5,201 flights, so OO 5555 is 14 points behind it. SkyWest flew 4,933 flights on the same city pair under all its flight numbers, including this one, and those ran 63.7% on time. Across its whole network SkyWest Airlines managed 79.0%, which this flight trails by 29 points.

OO 5555 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
OO 5555thin sample	363	50.1%	98 min	4.13%	F−
All SkyWest Airlines on ORD–MKE	4,933	63.7%	93 min	4.64%	D−
All carriers on ORD–MKE	5,201	64.1%	93 min	4.75%	D−
SkyWest Airlines, whole network	852,935	79.0%	88 min	1.77%	B

Across the year

OO 5555 quarter by quarter

Quarter by quarter OO 5555 held fairly steady: 53.4% in Jul–Sep 2025, 50.6% in Oct–Dec 2025, 46.5% in Jan–Mar 2026 and 50.0% in Apr–Jun 2026. A spread of 7 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights53.4%
Oct–Dec 202591 flights50.6%
Jan–Mar 202690 flights46.5%
Apr–Jun 202690 flights50.0%

Scale runs 40% to 60%. Rows with fewer than 30 flights show a dash.

By weekday, OO 5555 did best on Friday at 58.3% on time and worst on Sunday at 39.2%. Each day rests on about 52 flights, so a gap of 19 points is worth noticing but could still narrow in another year.

Delay causes

Why OO 5555 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 17,000 reported delay minutes.

Carrier
29%
Late-arriving aircraft
29%
National Airspace System
22%
Extreme weather
20%

Extreme weather accounts for 20% 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 3.2 times the usual weather exposure. The split is drawn from 16,927 delay minutes reported on OO 5555.

Cancellations run at 4.13%, 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. 23.3% 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 one other city pair in the data, including BNA to ORD (1), but none flew often enough under OO 5555 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ORD to MKE only.

One caution: this is a thin sample. 363 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 5555

For a booking, the cancellation rate is the figure to plan around on OO 5555: 4.13% of its 363 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.

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