Flight number record

OO 5231

SkyWest Airlines · South Bend to Chicago

Route: SBN → ORD
Departs: 07:30
Flights: 364
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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, 8 points worse than the national rate of 77.6%. 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 77.6%, so OO 5231 runs 8 points behind the country as a whole. Across a thousand flights that is about 79 extra late arrivals.

On time

69.7%

Arrivals under 15 minutes late, of 356 completed flights

Avg delay

89 min

Across delayed arrivals only, not all flights

Cancelled

1.92%

National rate is 1.81%

1 hour+ late

12.4%

National rate is 8.1%

These figures cover 364 flights between July 2025 and June 2026. Beyond the headline rate, 12.4% 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 5231 flies

OO 5231 flies SBN to ORD without a single fixed slot. Its most common scheduled departure was 07:30, used on 211 of 364 flights, with 07:35 (96 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 07:30211 flights58.0%
Departs 07:3596 flights26.4%

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 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 20 points worse at 69.7%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

OO 5231 next to SBN to ORD

Every carrier on SBN to ORD combined arrived on time 65.0% of the time across 2,705 flights, so OO 5231 is 5 points ahead of it. SkyWest flew 2,692 flights on the same city pair under all its flight numbers, including this one, and those ran 65.1% on time. Across its whole network SkyWest Airlines managed 79.0%, which this flight trails by 9 points.

OO 5231 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
OO 5231thin sample	364	69.7%	89 min	1.92%	C
All SkyWest Airlines on SBN–ORD	2,692	65.1%	95 min	3.79%	C−
All carriers on SBN–ORD	2,705	65.0%	95 min	3.81%	C−
SkyWest Airlines, whole network	852,935	79.0%	88 min	1.77%	B

Across the year

OO 5231 quarter by quarter

OO 5231 did not run the same all year. Its best quarter was Apr–Jun 2026 at 79.1% on time and its weakest Jan–Mar 2026 at 60.0%, a swing of 19 points on roughly 91 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 202592 flights78.0%
Oct–Dec 202592 flights60.7%
Jan–Mar 202689 flights60.0%
Apr–Jun 202691 flights79.1%

Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.

By weekday, OO 5231 did best on Wednesday at 83.7% on time and worst on Monday at 56.0%. Each day rests on about 52 flights, so a gap of 28 points is worth noticing but could still narrow in another year.

Delay causes

Why OO 5231 runs late

One category carries most of the weight here. Carrier accounts for 55% of the 9,645 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Carrier
55%
Extreme weather
15%
Late-arriving aircraft
15%
National Airspace System
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 2.5 times the usual weather exposure. The split is drawn from 9,645 delay minutes reported on OO 5231.

Cancellations sit at 1.92% against a national 1.81%, which is ordinary. Diversions add another 0.27%.

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. 12.4% 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.

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.

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