Carrier route record

OOSEA→DEN

SkyWest Airlines · Seattle to Denver

Flights: 221
Period: July 2025 to June 2026
Share of route: 3%
Carriers: 6

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with SkyWest Airlines.

SkyWest on SEA to DEN earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 221 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,905 at 87.5% on time.

United Airlines is the most reliable of the five carriers covered here at 87.5% on time across 1,905 flights.

On time

85.0%

Arrivals under 15 minutes late, of 220 completed flights

Avg delay

60 min

Across delayed arrivals only, not all flights

Cancelled

0.45%

National rate is 1.81%

Whole route

77.8%

Every carrier on SEA to DEN, 6,317 flights

These figures cover 221 flights between July 2025 and June 2026. The median arrival is 11 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.

Carrier by carrier

SkyWest against every carrier on SEA to DEN

SkyWest flew 221 of the 6,317 flights on SEA to DEN, about 3% of it. Its 85.0% on time is 7 points better than the route as a whole, which runs 77.8%. Ranked by on-time rate it is number two of six carriers on the route, where the range runs from United at 87.5% to Southwest at 69.0%.

The choice of carrier is not cosmetic here. United Airlines arrives on time 87.5% of the time; Southwest Airlines manages 69.0%. Sample sizes sit next to every figure, because a two-point gap across 1,345 flights means less than a ten-point one.

On-time performance by carrier on SEA to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	1,905	87.5%	73 min	0.84%	A+
SkyWest Airlines (this page)thin sample	221	85.0%	60 min	0.45%	A+
Alaska Airlines	1,558	75.9%	50 min	0.83%	B+
Frontier Airlines	419	74.9%	75 min	1.91%	C
Delta Air Lines	869	73.3%	58 min	0.92%	C+
Southwest Airlines	1,345	69.0%	52 min	0.59%	C+

The spread between United and Southwest is 19 points, wide enough that it should decide the booking. On a hundred trips that is 19 more arrivals inside the on-time window.

Departure window

When SkyWest runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 221 flights.

5am–8am—
8am–11am98 flights88.8%
11am–2pm98 flights82.5%
2pm–5pm24 flights—
5pm–8pm1 flights—
8pm–5am—

Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.

The weak window here is the middle of the day, not the evening: 11am–2pm runs 82.5% on time against 88.8% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8am–11am window is the busiest, with 98 flights scheduled in it.

Across the year

SkyWest on SEA to DEN through the year

Jan–Mar 2026172 flights86.0%
Apr–Jun 202649 flights81.6%

Scale runs 75% to 90%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 85.0% on time across 221 flights.

Split by quarter, SkyWest on SEA to DEN logged 172 flights in Jan–Mar 2026 and 49 flights in Apr–Jun 2026. Fewer than three of those quarters carried the 30 completed flights this site needs before printing a rate, so the 85.0% annual figure is the one to use.

Across the week, Sunday is the strongest day at 93.5% on time and Friday the weakest at 76.7%. 17 points is a smaller lever than departure hour, but it is free.

Delay causes

Why SkyWest runs late on this route

One category carries most of the weight here. Carrier accounts for 44% of the 1,984 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
44%
Extreme weather
38%
National Airspace System
18%

Extreme weather accounts for 38% 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 monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 6.1 times the usual weather exposure. The split is drawn from 1,984 reported delay minutes.

The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 877 of the 1,984 delay minutes reported here.

Cancellations are rare at 0.45%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here costs

5.5% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.

The 1,024 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 return leg is a different operation and performs like one: it runs 75.8% on time across 220 flights, 9 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 9 points of difference.

One caution: this is a thin sample. 221 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 SkyWest on SEA to DEN

Put together: treat all of this as provisional. 221 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 85.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 220 completed flights over 12 months sit behind that.

Where to go next

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