Flight number record
OO 5231
SkyWest Airlines · South Bend to Chicago
- Route
- SBN → ORD
- Departs
- 07:30
- Flights
- 364
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 5231, 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 5231 sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.3%. The late ones land an hour and a half behind schedule. That rests on 364 flights, with a median arrival 1 minute late.
The national on-time rate over the same period is 77.3%, so OO 5231 runs 7 points behind the country as a whole. Across a thousand flights that is about 70 extra late arrivals.
Key figures
On time
70.3%
Arrivals under 15 minutes late, of 354 completed flights
Avg delay
93 min
Across delayed arrivals only, not all flights
Cancelled
2.47%
National rate is 1.89%
1 hour+ late
12.4%
National rate is 8.3%
These figures cover 364 flights between September 2025 and August 2026. Beyond the headline rate, 12.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When OO 5231 flies
OO 5231 flies SBN to ORD without a single fixed slot. Its most common scheduled departure was 07:30, used on 162 of 364 flights, with 07:35 (83 flights) and 07:45 (47 flights) next.
- Departs 07:30162 flights44.5%
- Departs 07:3583 flights22.8%
- Departs 07:4547 flights12.9%
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 07:30 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and OO 5231 runs 19 points worse at 70.3%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
OO 5231 next to SBN to ORD
Every carrier on SBN to ORD combined arrived on time 65.5% of the time across 2,790 flights, so OO 5231 is 5 points ahead of it. SkyWest flew 2,777 flights on the same city pair under all its flight numbers, including this one, and those ran 65.7% on time. Across its whole network SkyWest Airlines managed 78.7%, which this flight trails by 8 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 5231thin sample | 364 | 70.3% | 93 min | 2.47% | C |
| All SkyWest Airlines on SBN–ORD | 2,777 | 65.7% | 100 min | 3.85% | C− |
| All carriers on SBN–ORD | 2,790 | 65.5% | 99 min | 3.87% | C− |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 5231 quarter by quarter
OO 5231 did not run the same all year. Its best quarter was Jul–Sep 2026 at 81.4% on time and its weakest Jan–Mar 2026 at 60.0%, a swing of 21 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 flights80.0%
- Oct–Dec 202592 flights60.7%
- Jan–Mar 202689 flights60.0%
- Apr–Jun 202691 flights79.1%
- Jul–Sep 202662 flights81.4%
Scale runs 50% to 85%.
By weekday, OO 5231 did best on Wednesday at 79.2% on time and worst on Monday at 58.0%. Each day rests on about 52 flights, so a gap of 21 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late OO 5231 runs when it is late
The 105 late arrivals split 39 under half an hour, 22 between 30 and 60 minutes, and 44 an hour or more.
- 15+ min early84 flights23.7%
- Within 15 min165 flights46.6%
- 15–29 min late39 flights11.0%
- 30–59 min late22 flights6.2%
- 1–2 hours late14 flights4.0%
- 2+ hours late30 flights8.5%
Scale runs 0% to 100%.
Share of 354 completed flights by arrival against schedule.
10 of 71 late departures made up the time and arrived on time, 14% of them. In the other direction, 44 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 5231
The latest arrival of the period was on 25 November 2025, 8 hours 58 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The five worst days are spread across November, February, December, July and January, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 25 November 2025 | 8 hours 58 minutes | Carrier |
| 3 February 2026 | 7 hours 49 minutes | Late-arriving aircraft |
| 12 December 2025 | 7 hours 48 minutes | Carrier |
| 5 July 2026 | 7 hours 2 minutes | Extreme weather |
| 19 January 2026 | 6 hours 49 minutes | Late-arriving aircraft |
Delay causes
Why OO 5231 runs late
Carrier accounts for 55% of the 9,714 delay minutes carriers reported here, and the remaining four split what is left.
- 55%Carrier
- 16%Extreme weather
- 15%Late-arriving aircraft
- 14%National Airspace System
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 2.7 times the usual weather exposure. The split is drawn from 9,714 delay minutes reported on OO 5231.
Cancellations sit at 2.47% against a national 1.89%, which is ordinary. Diversions add another 0.27%.
Connections and routes
What a delay on this flight costs
12.4% 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.
Every one of the 364 flights under OO 5231 in the data flew SBN to ORD. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 364 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 5231
For a booking, OO 5231 is a flight to put a long connection behind. 12.4% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- SBN to ORD, every carrier and departure
- ORD to SBN, the return direction
- SkyWest Airlines 5723 on the same route76.6%
- SkyWest Airlines 5675 on the same route51.2%
- SkyWest Airlines 4794 on the same route68.9%
- SkyWest Airlines 5489 on the same route61.2%
- 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
- How often a connection fails at the major US hubs
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.