Flight number record

OO 4231

SkyWest Airlines · Sault Ste. Marie to Detroit

Route: CIU → DTW
Departs: 13:40
Flights: 363
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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−, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That is a workable record, not a spotless one. That rests on 363 flights, with a median arrival 13 minutes early.

Set against the rest of the country, OO 4231's record is 5 points better than the US average of 77.6%. That gap is worth roughly 48 fewer late arrivals for every thousand flights.

On time

82.4%

Arrivals under 15 minutes late, of 341 completed flights

Avg delay

114 min

Across delayed arrivals only, not all flights

Cancelled

5.79%

National rate is 1.81%

1 hour+ late

10.9%

National rate is 8.1%

These figures cover 363 flights between July 2025 and June 2026. Beyond the headline rate, 10.9% 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 4231 flies

OO 4231 flies CIU to DTW without a single fixed slot. Its most common scheduled departure was 13:40, used on 92 of 363 flights, with 15:50 (61 flights) and 16:04 (38 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 13:4092 flights25.3%
Departs 15:5061 flights16.8%
Departs 16:0438 flights10.5%

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 13:40 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and OO 4231 runs 4 points better at 82.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

OO 4231 next to CIU to DTW

Across its whole network SkyWest Airlines managed 79.0%, which this flight beats by 3 points.

OO 4231 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
OO 4231thin sample	363	82.4%	114 min	5.79%	B−
All SkyWest Airlines on CIU–DTWthin sample	363	82.4%	114 min	5.79%	B−
All carriers on CIU–DTWthin sample	363	82.4%	114 min	5.79%	B−
SkyWest Airlines, whole network	852,935	79.0%	88 min	1.77%	B

Across the year

OO 4231 quarter by quarter

OO 4231 did not run the same all year. Its best quarter was Apr–Jun 2026 at 89.5% on time and its weakest Jan–Mar 2026 at 68.8%, a swing of 21 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 flights85.7%
Oct–Dec 202590 flights83.9%
Jan–Mar 202690 flights68.8%
Apr–Jun 202691 flights89.5%

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, OO 4231 did best on Wednesday at 91.7% on time and worst on Saturday at 78.0%. Each day rests on about 52 flights, so a gap of 14 points is worth noticing but could still narrow in another year.

Delay causes

Why OO 4231 runs late

One category carries most of the weight here. Carrier accounts for 56% of the 6,818 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
56%
Extreme weather
35%
National Airspace System
8%

Extreme weather accounts for 35% 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 5.7 times the usual weather exposure. The split is drawn from 6,818 delay minutes reported on OO 4231.

Cancellations run at 5.79%, against 1.81% nationally. That is roughly 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.9% 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 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: 5.79% 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.

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