Flight number record

OO 4278

SkyWest Airlines · Detroit to Sault Ste. Marie

Route: DTW → CIU
Departs: 17:55
Flights: 363
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s OO 4278, 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 4278 sits in the middle of the pack with a C−. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land close to two hours behind schedule. That rests on 363 flights, with a median arrival 11 minutes early.

The national on-time rate over the same period is 77.6%, so OO 4278 runs 4 points behind the country as a whole. Across a thousand flights that is about 40 extra late arrivals.

On time

73.6%

Arrivals under 15 minutes late, of 337 completed flights

Avg delay

111 min

Across delayed arrivals only, not all flights

Cancelled

6.34%

National rate is 1.81%

1 hour+ late

16.3%

National rate is 8.1%

These figures cover 363 flights between July 2025 and June 2026. Beyond the headline rate, 16.3% 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 4278 flies

OO 4278 flies DTW to CIU without a single fixed slot. Its most common scheduled departure was 17:55, used on 161 of 363 flights, with 18:25 (62 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 17:55161 flights44.4%
Departs 18:2562 flights17.1%

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 17:55 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and OO 4278 runs 5 points better at 73.6%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

OO 4278 next to DTW to CIU

Across its whole network SkyWest Airlines managed 79.0%, which this flight trails by 5 points.

OO 4278 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
OO 4278thin sample	363	73.6%	111 min	6.34%	C−
All SkyWest Airlines on DTW–CIUthin sample	363	73.6%	111 min	6.34%	C−
All carriers on DTW–CIUthin sample	363	73.6%	111 min	6.34%	C−
SkyWest Airlines, whole network	852,935	79.0%	88 min	1.77%	B

Across the year

OO 4278 quarter by quarter

OO 4278 did not run the same all year. Its best quarter was Oct–Dec 2025 at 79.3% on time and its weakest Jan–Mar 2026 at 54.8%, a swing of 25 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 flights79.1%
Oct–Dec 202590 flights79.3%
Jan–Mar 202690 flights54.8%
Apr–Jun 202691 flights77.9%

Scale runs 45% to 85%. Rows with fewer than 30 flights show a dash.

By weekday, OO 4278 did best on Thursday at 83.3% on time and worst on Sunday at 59.6%. Each day rests on about 52 flights, so a gap of 24 points is worth noticing but could still narrow in another year.

Delay causes

Why OO 4278 runs late

One category carries most of the weight here. Carrier accounts for 79% of the 9,845 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
79%
Extreme weather
16%
National Airspace System
5%

Extreme weather accounts for 16% 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 9,845 delay minutes reported on OO 4278.

Cancellations run at 6.34%, against 1.81% 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 16.3% 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.

Every one of the 363 flights under OO 4278 in the data flew DTW to CIU. 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 4278

For a booking, the cancellation rate is the figure to plan around on OO 4278: 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.

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