Flight number record
OO 4231
SkyWest Airlines · Sault Ste. Marie to Detroit
- Route
- CIU → DTW
- Departs
- 16:04
- Flights
- 363
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 4231, 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 4231 lands a B−, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That rests on 363 flights, with a median arrival 16 minutes early.
Set against the rest of the country, OO 4231's record is 6 points better than the US average of 77.3%. That gap is worth roughly 56 fewer late arrivals for every thousand flights.
Key figures
On time
82.9%
Arrivals under 15 minutes late, of 340 completed flights
Avg delay
105 min
Across delayed arrivals only, not all flights
Cancelled
6.34%
National rate is 1.89%
1 hour+ late
9.7%
National rate is 8.3%
These figures cover 363 flights between September 2025 and August 2026. Beyond the headline rate, 9.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When OO 4231 flies
OO 4231 flies CIU to DTW without a single fixed slot. Its most common scheduled departure was 16:04, used on 67 of 363 flights, with 16:13 (63 flights) and 15:50 (61 flights) next.
- Departs 16:0467 flights18.5%
- Departs 16:1363 flights17.4%
- Departs 15:5061 flights16.8%
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 16:04 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and OO 4231 runs 11 points better at 82.9%. 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 4231 next to CIU to DTW
Across its whole network SkyWest Airlines managed 78.7%, which this flight beats by 4 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 4231thin sample | 363 | 82.9% | 105 min | 6.34% | B− |
| All SkyWest Airlines on CIU–DTWthin sample | 363 | 82.9% | 105 min | 6.34% | B− |
| All carriers on CIU–DTWthin sample | 363 | 82.9% | 105 min | 6.34% | B− |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 4231 quarter by quarter
OO 4231 did not run the same all year. Its best quarter was Jul–Sep 2025 at 90.0% on time and its weakest Jan–Mar 2026 at 68.8%, 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 flights90.0%
- Oct–Dec 202590 flights83.9%
- Jan–Mar 202690 flights68.8%
- Apr–Jun 202691 flights89.5%
- Jul–Sep 202662 flights86.7%
Scale runs 60% to 95%.
By weekday, OO 4231 did best on Wednesday at 91.5% on time and worst on Friday at 79.2%. Each day rests on about 52 flights, so a gap of 12 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late OO 4231 runs when it is late
OO 4231 often beats the schedule: 184 of 340 completed flights, 54%, arrived 15 minutes or more early. When OO 4231 is late it tends to be very late: 33 of its 58 late arrivals were an hour or more behind, and 18 were two hours or more.
- 15+ min early184 flights54.1%
- Within 15 min98 flights28.8%
- 15–29 min late14 flights4.1%
- 30–59 min late11 flights3.2%
- 1–2 hours late15 flights4.4%
- 2+ hours late18 flights5.3%
Scale runs 0% to 100%.
Share of 340 completed flights by arrival against schedule.
9 of 60 late departures made up the time and arrived on time, 15% of them. 7 flights left on time and still arrived late.
The worst days
Worst days for OO 4231
The latest arrival of the period was on 21 February 2026, 7 hours 35 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 February 2026 | 7 hours 35 minutes | Carrier |
| 23 January 2026 | 5 hours 54 minutes | Extreme weather |
| 28 December 2025 | 5 hours 17 minutes | National Airspace System |
| 18 January 2026 | 4 hours 58 minutes | Carrier |
| 17 April 2026 | 4 hours 55 minutes | Carrier |
Delay causes
Why OO 4231 runs late
Carrier accounts for 49% of the 6,091 delay minutes carriers reported here, and the remaining four split what is left.
- 49%Carrier
- 40%Extreme weather
- 11%National Airspace System
Extreme weather accounts for 40% 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 6.6 times the usual weather exposure. The split is drawn from 6,091 delay minutes reported on OO 4231.
Cancellations run at 6.34%, 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
9.7% 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 363 flights under OO 4231 in the data flew CIU to DTW. 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. 363 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 4231
For a booking, the cancellation rate is the figure to plan around on OO 4231: 6.34% of its 363 scheduled flights did not operate. A late arrival costs close to two hours, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- Detroit Metropolitan Wayne County (DTW) 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
- What a cancellation rate actually tells you (and what it hides)
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.