Flight number record
OO 5555
SkyWest Airlines · Chicago to Milwaukee
- Route
- ORD → MKE
- Departs
- 17:45
- Flights
- 363
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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 52.2% of flights arrive inside the 15-minute window, 25 points worse than the national rate of 77.3%. 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 12 minutes late.
The national on-time rate over the same period is 77.3%, so OO 5555 runs 25 points behind the country as a whole. Across a thousand flights that is about 251 extra late arrivals.
Key figures
On time
52.2%
Arrivals under 15 minutes late, of 347 completed flights
Avg delay
96 min
Across delayed arrivals only, not all flights
Cancelled
4.41%
National rate is 1.89%
1 hour+ late
22.2%
National rate is 8.3%
These figures cover 363 flights between September 2025 and August 2026. Beyond the headline rate, 22.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When OO 5555 flies
OO 5555 flies ORD to MKE without a single fixed slot. Its most common scheduled departure was 17:45, used on 179 of 363 flights, with 17:50 (162 flights) next.
- Departs 17:45179 flights49.3%
- Departs 17:50162 flights44.6%
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 17:45 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and OO 5555 runs 16 points worse at 52.2%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
OO 5555 next to ORD to MKE
Every carrier on ORD to MKE combined arrived on time 64.3% of the time across 5,344 flights, so OO 5555 is 12 points behind it. SkyWest flew 5,047 flights on the same city pair under all its flight numbers, including this one, and those ran 63.9% on time. Across its whole network SkyWest Airlines managed 78.7%, which this flight trails by 27 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 5555thin sample | 363 | 52.2% | 96 min | 4.41% | F− |
| All SkyWest Airlines on ORD–MKE | 5,047 | 63.9% | 92 min | 4.58% | D− |
| All carriers on ORD–MKE | 5,344 | 64.3% | 92 min | 4.68% | D− |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 5555 quarter by quarter
OO 5555 did not run the same all year. Its best quarter was Jul–Sep 2026 at 62.1% on time and its weakest Jan–Mar 2026 at 46.5%, a swing of 16 points on roughly 73 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights60.0%
- Oct–Dec 202591 flights50.6%
- Jan–Mar 202690 flights46.5%
- Apr–Jun 202690 flights50.0%
- Jul–Sep 202662 flights62.1%
Scale runs 40% to 70%.
By weekday, OO 5555 did best on Friday at 59.2% on time and worst on Sunday at 44.0%. Each day rests on about 52 flights, so a gap of 15 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late OO 5555 runs when it is late
The 166 late arrivals split 39 under half an hour, 50 between 30 and 60 minutes, and 77 an hour or more.
- 15+ min early45 flights13.0%
- Within 15 min136 flights39.2%
- 15–29 min late39 flights11.2%
- 30–59 min late50 flights14.4%
- 1–2 hours late39 flights11.2%
- 2+ hours late38 flights11.0%
Scale runs 0% to 100%.
Share of 347 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 130 departures that left 15 minutes late or more, only 7 made it up before arrival. In the other direction, 43 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 MKE.
The worst days
Worst days for OO 5555
The latest arrival of the period was on 22 January 2026, 14 hours 59 minutes behind schedule; most of its delay minutes were filed as extreme weather. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 22 January 2026 | 14 hours 59 minutes | Extreme weather |
| 30 December 2025 | 14 hours 32 minutes | Late-arriving aircraft |
| 18 May 2026 | 11 hours 43 minutes | Extreme weather |
| 30 November 2025 | 6 hours 1 minute | Late-arriving aircraft |
| 17 June 2026 | 5 hours 44 minutes | Extreme weather |
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 16,000 reported delay minutes.
- 31%Late-arriving aircraft
- 26%Carrier
- 22%National Airspace System
- 20%Extreme weather
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 3.4 times the usual weather exposure. The split is drawn from 15,909 delay minutes reported on OO 5555.
Cancellations run at 4.41%, 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
22.2% 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 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: 4.41% 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.
Related
Where to go next
- ORD to MKE, every carrier and departure
- MKE to ORD, the return direction
- SkyWest Airlines 5362 on the same route69.9%
- SkyWest Airlines 4711 on the same route66.3%
- Chicago O'Hare International (ORD) delay statistics
- Milwaukee Mitchell International (MKE) delay statistics
- SkyWest Airlines on-time record
- Every SkyWest Airlines flight number with a record
- The most and least reliable flight numbers in the US
- What a cancellation rate actually tells you (and what it hides)
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 ; recomputed monthly. How this data is collected.