Flight number record
OO 5521
SkyWest Airlines · Chicago to Columbia
- Route
- ORD → COU
- Departs
- 13:00
- Flights
- 289
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 5521, 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 5521 sits in the middle of the pack with a C−. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.3%. The late ones land an hour and a half behind schedule. That rests on 289 flights, with a median arrival 5 minutes early.
The national on-time rate over the same period is 77.3%, so OO 5521 runs 6 points behind the country as a whole. Across a thousand flights that is about 60 extra late arrivals.
Key figures
On time
71.3%
Arrivals under 15 minutes late, of 279 completed flights
Avg delay
84 min
Across delayed arrivals only, not all flights
Cancelled
3.11%
National rate is 1.89%
1 hour+ late
13.6%
National rate is 8.3%
These figures cover 289 flights between September 2025 and August 2026. Beyond the headline rate, 13.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When OO 5521 flies
OO 5521 flies ORD to COU without a single fixed slot. Its most common scheduled departure was 13:00, used on 98 of 289 flights, with 13:15 (80 flights) and 12:45 (51 flights) next.
- Departs 13:0098 flights33.9%
- Departs 13:1580 flights27.7%
- Departs 12:4551 flights17.6%
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 13:00 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and OO 5521 runs 7 points worse at 71.3%. 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 5521 next to ORD to COU
Every carrier on ORD to COU combined arrived on time 70.8% of the time across 2,054 flights, so OO 5521 is about level with it. SkyWest flew 903 flights on the same city pair under all its flight numbers, including this one, and those ran 66.7% on time. Across its whole network SkyWest Airlines managed 78.7%, which this flight trails by 7 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 5521thin sample | 289 | 71.3% | 84 min | 3.11% | C− |
| All SkyWest Airlines on ORD–COU | 903 | 66.7% | 103 min | 5.09% | C− |
| All carriers on ORD–COU | 2,054 | 70.8% | 86 min | 3.75% | C− |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 5521 quarter by quarter
OO 5521 did not run the same all year. Its best quarter was Apr–Jun 2026 at 78.4% on time and its weakest Jan–Mar 2026 at 64.7%, a swing of 14 points on roughly 72 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.
- Oct–Dec 202567 flights66.7%
- Jan–Mar 202690 flights64.7%
- Apr–Jun 202691 flights78.4%
- Jul–Sep 202641 flights77.5%
Scale runs 55% to 85%.
By weekday, OO 5521 ranged from 67.5% on Sunday to 76.3% on Monday. With about 41 flights behind each day, a spread of 9 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late OO 5521 runs when it is late
OO 5521 often beats the schedule: 92 of 279 completed flights, 33%, arrived 15 minutes or more early. The 80 late arrivals split 20 under half an hour, 22 between 30 and 60 minutes, and 38 an hour or more.
- 15+ min early92 flights33.0%
- Within 15 min107 flights38.4%
- 15–29 min late20 flights7.2%
- 30–59 min late22 flights7.9%
- 1–2 hours late21 flights7.5%
- 2+ hours late17 flights6.1%
Scale runs 0% to 100%.
Share of 279 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 70 departures that left 15 minutes late or more, only 7 made it up before arrival. In the other direction, 17 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 COU.
The worst days
Worst days for OO 5521
The latest arrival of the period was on 7 June 2026, 5 hours 42 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across June, November, December and April, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 June 2026 | 5 hours 42 minutes | Late-arriving aircraft |
| 10 November 2025 | 4 hours 57 minutes | National Airspace System |
| 7 December 2025 | 4 hours 49 minutes | National Airspace System |
| 2 December 2025 | 4 hours 33 minutes | Late-arriving aircraft |
| 16 April 2026 | 4 hours 15 minutes | Carrier |
Delay causes
Why OO 5521 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 6,706 reported delay minutes.
- 35%Carrier
- 34%Late-arriving aircraft
- 26%National Airspace System
- 5%Extreme weather
34% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 6,706 reported delay minutes here, that single category outweighs weather by 7 to one. The split is drawn from 6,706 delay minutes reported on OO 5521.
Cancellations run at 3.11%, against 1.89% nationally. That is about one flight in 30 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
13.6% 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 SCE to ORD (35), SDF to ORD (30) and CLE to ORD (5), but none flew often enough under OO 5521 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ORD to COU only.
One caution: this is a thin sample. 289 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 5521
For a booking, the cancellation rate is the figure to plan around on OO 5521: 3.11% of its 289 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 COU, every carrier and departure
- COU to ORD, the return direction
- Envoy Air 3745 on the same route66.9%
- Chicago O'Hare International (ORD) 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
- Why the first flight of the morning is statistically safest
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.