Flight number record

OO 4791

SkyWest Airlines · Chicago to South Bend

Route: ORD → SBN
Departs: 10:35
Flights: 355
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s OO 4791, 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 4791 draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is an hour and a half behind schedule. Build slack into anything you connect to. That rests on 355 flights, with a median arrival 3 minutes early.

The national on-time rate over the same period is 77.6%, so OO 4791 runs 10 points behind the country as a whole. Across a thousand flights that is about 98 extra late arrivals.

On time

67.8%

Arrivals under 15 minutes late, of 345 completed flights

Avg delay

91 min

Across delayed arrivals only, not all flights

Cancelled

2.82%

National rate is 1.81%

1 hour+ late

13.3%

National rate is 8.1%

These figures cover 355 flights between July 2025 and June 2026. Beyond the headline rate, 13.3% 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 4791 flies

OO 4791 flies ORD to SBN without a single fixed slot. Its most common scheduled departure was 10:35, used on 250 of 355 flights, with 10:30 (53 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 10:35250 flights70.4%
Departs 10:3053 flights14.9%

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 10:35 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and OO 4791 runs 16 points worse at 67.8%. 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 4791 next to ORD to SBN

Every carrier on ORD to SBN combined arrived on time 62.7% of the time across 2,704 flights, so OO 4791 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 62.5% on time. Across its whole network SkyWest Airlines managed 79.0%, which this flight trails by 11 points.

OO 4791 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
OO 4791thin sample	355	67.8%	91 min	2.82%	C
All SkyWest Airlines on ORD–SBN	2,692	62.5%	87 min	4.27%	D−
All carriers on ORD–SBN	2,704	62.7%	87 min	4.25%	D−
SkyWest Airlines, whole network	852,935	79.0%	88 min	1.77%	B

Across the year

OO 4791 quarter by quarter

OO 4791 did not run the same all year. Its best quarter was Jul–Sep 2025 at 81.1% on time and its weakest Jan–Mar 2026 at 57.1%, a swing of 24 points on roughly 89 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 flights81.1%
Oct–Dec 202590 flights66.7%
Jan–Mar 202688 flights57.1%
Apr–Jun 202685 flights65.5%

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

By weekday, OO 4791 did best on Thursday at 83.3% on time and worst on Saturday at 61.2%. Each day rests on about 51 flights, so a gap of 22 points is worth noticing but could still narrow in another year.

Delay causes

Why OO 4791 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 10,000 reported delay minutes.

Carrier
37%
Late-arriving aircraft
33%
National Airspace System
27%
Extreme weather
2%

The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 3,753 of the 10,000 delay minutes reported here. The split is drawn from 10,078 delay minutes reported on OO 4791.

Cancellations run at 2.82%, against 1.81% nationally. That is roughly one flight in 40 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. 13.3% 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 ORD to BDL (6), but none flew often enough under OO 4791 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ORD to SBN only.

One caution: this is a thin sample. 355 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 4791

For a booking, the cancellation rate is the figure to plan around on OO 4791: 2.82% of its 355 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