Flight number record
OO 4636
SkyWest Airlines · Chicago to South Bend
- Route
- ORD → SBN
- Departs
- 17:50
- Flights
- 309
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 4636, 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 4636 earns an F−, which is as low as this site's scale goes for a reason. Only 52.4% 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 309 flights, with a median arrival 10 minutes late.
The national on-time rate over the same period is 77.3%, so OO 4636 runs 25 points behind the country as a whole. Across a thousand flights that is about 249 extra late arrivals.
Key figures
On time
52.4%
Arrivals under 15 minutes late, of 288 completed flights
Avg delay
87 min
Across delayed arrivals only, not all flights
Cancelled
6.80%
National rate is 1.89%
1 hour+ late
20.8%
National rate is 8.3%
These figures cover 309 flights between September 2025 and August 2026. Beyond the headline rate, 20.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When OO 4636 flies
OO 4636 flies ORD to SBN without a single fixed slot. Its most common scheduled departure was 17:50, used on 69 of 309 flights, with 17:55 (56 flights) and 17:52 (47 flights) next.
- Departs 17:5069 flights22.3%
- Departs 17:5556 flights18.1%
- Departs 17:5247 flights15.2%
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 17:50 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and OO 4636 runs 16 points worse at 52.4%. 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 4636 next to ORD to SBN
Every carrier on ORD to SBN combined arrived on time 63.1% of the time across 2,789 flights, so OO 4636 is 11 points behind it. SkyWest flew 2,777 flights on the same city pair under all its flight numbers, including this one, and those ran 63.0% on time. Across its whole network SkyWest Airlines managed 78.7%, which this flight trails by 26 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 4636thin sample | 309 | 52.4% | 87 min | 6.80% | F− |
| All SkyWest Airlines on ORD–SBN | 2,777 | 63.0% | 87 min | 4.39% | D− |
| All carriers on ORD–SBN | 2,789 | 63.1% | 87 min | 4.37% | D− |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 4636 quarter by quarter
OO 4636 did not run the same all year. Its best quarter was Jul–Sep 2026 at 57.9% on time and its weakest Jan–Mar 2026 at 46.3%, a swing of 12 points on roughly 77 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 202524 flights—
- Oct–Dec 202563 flights49.2%
- Jan–Mar 202690 flights46.3%
- Apr–Jun 202691 flights51.8%
- Jul–Sep 202641 flights57.9%
Scale runs 40% to 65%. Rows with fewer than 30 flights show a dash.
By weekday, OO 4636 did best on Thursday at 62.5% on time and worst on Saturday at 41.0%. Each day rests on about 44 flights, so a gap of 22 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late OO 4636 runs when it is late
The 137 late arrivals split 44 under half an hour, 33 between 30 and 60 minutes, and 60 an hour or more.
- 15+ min early53 flights18.4%
- Within 15 min98 flights34.0%
- 15–29 min late44 flights15.3%
- 30–59 min late33 flights11.5%
- 1–2 hours late31 flights10.8%
- 2+ hours late29 flights10.1%
Scale runs 0% to 100%.
Share of 288 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 90 departures that left 15 minutes late or more, only 3 made it up before arrival. In the other direction, 50 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 SBN.
The worst days
Worst days for OO 4636
The latest arrival of the period was on 19 April 2026, 14 hours 4 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in December 2025.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 19 April 2026 | 14 hours 4 minutes | Carrier |
| 19 January 2026 | 13 hours 48 minutes | Carrier |
| 7 December 2025 | 7 hours 5 minutes | National Airspace System |
| 30 December 2025 | 5 hours 49 minutes | Late-arriving aircraft |
| 31 December 2025 | 5 hours 7 minutes | Late-arriving aircraft |
Delay causes
Why OO 4636 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 12,000 reported delay minutes.
- 40%Carrier
- 33%Late-arriving aircraft
- 22%National Airspace System
- 5%Extreme weather
The largest share of delay minutes, 40%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 4,774 of the 12,000 delay minutes reported here. The split is drawn from 11,972 delay minutes reported on OO 4636.
Cancellations run at 6.80%, against 1.89% nationally. That is about one flight in fifteen 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
20.8% 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 three other city pairs in the data, including ORD to ABE (31), BGR to ORD (21) and OMA to ORD (1), but none flew often enough under OO 4636 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. 309 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 4636
For a booking, the cancellation rate is the figure to plan around on OO 4636: 6.80% of its 309 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 SBN, every carrier and departure
- SBN to ORD, the return direction
- SkyWest Airlines 5499 on the same route58.5%
- SkyWest Airlines 5274 on the same route67.0%
- SkyWest Airlines 5505 on the same route62.3%
- SkyWest Airlines 4791 on the same route65.6%
- SkyWest Airlines 5887 on the same route66.1%
- 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.