Flight number record

OO 4042

SkyWest Airlines · Ontario to Seattle

Route: ONT → SEA
Departs: 06:00
Flights: 286
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s OO 4042, 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 4042 earns an A+. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 17 points better than the national rate of 77.6%. When something does go wrong the average delay runs close to two hours. That rests on 286 flights, with a median arrival 10 minutes early.

Set against the rest of the country, OO 4042's record is 17 points better than the US average of 77.6%. That gap is worth roughly 168 fewer late arrivals for every thousand flights.

On time

94.4%

Arrivals under 15 minutes late, of 284 completed flights

Avg delay

107 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

1 hour+ late

2.1%

National rate is 8.1%

These figures cover 286 flights between July 2025 and June 2026. The median arrival is 10 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Schedule

When OO 4042 flies

OO 4042 flies ONT to SEA without a single fixed slot. Its most common scheduled departure was 06:00, used on 92 of 286 flights, with 07:30 (62 flights) and 06:25 (41 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 06:0092 flights32.2%
Departs 07:3062 flights21.7%
Departs 06:2541 flights14.3%

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 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and OO 4042 runs 5 points better at 94.4%. 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 4042 next to ONT to SEA

Every carrier on ONT to SEA combined arrived on time 86.4% of the time across 2,551 flights, so OO 4042 is 8 points ahead of it. SkyWest flew 1,085 flights on the same city pair under all its flight numbers, including this one, and those ran 92.1% on time. Across its whole network SkyWest Airlines managed 79.0%, which this flight beats by 15 points.

OO 4042 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
OO 4042thin sample	286	94.4%	107 min	0.00%	A+
All SkyWest Airlines on ONT–SEA	1,085	92.1%	83 min	0.28%	A+
All carriers on ONT–SEA	2,551	86.4%	63 min	1.29%	A
SkyWest Airlines, whole network	852,935	79.0%	88 min	1.77%	B

Across the year

OO 4042 quarter by quarter

Quarter by quarter OO 4042 held fairly steady: 94.5% in Jul–Sep 2025, 96.7% in Oct–Dec 2025 and 91.1% in Jan–Mar 2026. A spread of 6 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights94.5%
Oct–Dec 202592 flights96.7%
Jan–Mar 202690 flights91.1%
Apr–Jun 202612 flights—

Scale runs 85% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, OO 4042 ranged from 90.0% on Thursday to 100.0% on Sunday. With about 41 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.

Delay causes

Why OO 4042 runs late

One category carries most of the weight here. Carrier accounts for 77% of the 1,707 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
77%
Extreme weather
19%
National Airspace System
4%

Extreme weather accounts for 19% 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 3.1 times the usual weather exposure. The split is drawn from 1,707 delay minutes reported on OO 4042.

Cancellations are rare at 0.00%, below the national 1.81% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.

Connections and routes

What a delay on this flight costs

Badly late arrivals are rare here: only 2.1% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

The 956 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The same number turns up on three other city pairs in the data, including PSP to SLC (55), SLC to PSP (55) and CLE to DTW (7), but none flew often enough under OO 4042 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ONT to SEA only.

One caution: this is a thin sample. 286 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 4042

For a booking, OO 4042 has one of the better records a US domestic flight can show: 94.4% on time and 0.00% cancelled. That is a base rate, not a promise about any single day.

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