Carrier performance at one airport

OO→SEA

SkyWest Airlines at Seattle-Tacoma International

Departures: 29,109
Period: July 2025 to June 2026
Routes: 25
Rank here: #2 of 10

SkyWest Airlines at Seattle earns a 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 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 29,109 flights, of which Envoy Air flew 691 at 86.9% on time.

Measured against the airport rather than the country, SkyWest Airlines runs 7 points ahead of the 79.4% weighted average across all carriers at SEA. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.

On time

86.1%

28,865 completed departures

Avg delay

58 min

Across delayed flights only

Cancelled

0.71%

At SEA, this carrier only

Rank here

Of 10 carriers clearing the floor at SEA

These figures cover 29,000 flights between July 2025 and June 2026. The median arrival is 8 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.

Against the competition

Every carrier at SEA, ranked

The choice of carrier is not cosmetic here. Envoy Air arrives on time 86.9% of the time; JetBlue Airways manages 59.6%. Sample sizes sit next to every figure, because a two-point gap across 413 flights means less than a ten-point one.

On-time performance of all carriers departing SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Envoy Air	691	86.9%	71 min	0.00%	A+
SkyWest Airlines (this page)	29,109	86.1%	58 min	0.71%	A+
Delta Air Lines	32,257	81.5%	65 min	1.05%	B
United Airlines	8,804	80.2%	76 min	0.80%	B+
American Airlines	6,630	79.2%	97 min	2.07%	B
Alaska Airlines	76,697	77.2%	47 min	1.05%	B
Frontier Airlines	1,401	73.6%	90 min	2.28%	C
Southwest Airlines	8,105	70.0%	48 min	0.41%	C+
Hawaiian Airlines	1,034	60.5%	82 min	1.26%	D
JetBlue Airways	413	59.6%	109 min	0.73%	D+

The spread between Envoy and JetBlue is 27 points, wide enough that it should decide the booking. On a hundred trips that is 27 more arrivals inside the on-time window.

Route by route

Where SkyWest Airlines flies from SEA

SkyWest Airlines operates 25 routes out of SEA with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.

SkyWest Airlines routes from SEA
Route	Flights	On time	Avg delay	Cancelled	Grade
SEA to PDX · Portland	3,343	86.1%	53 min	0.51%	A+
SEA to BOI · Boise	3,081	87.2%	52 min	0.19%	A+
SEA to GEG · Spokane	3,058	87.7%	55 min	1.05%	A
SEA to SMF · Sacramento	1,941	89.3%	62 min	0.26%	A+
SEA to EUG · Eugene	1,562	87.1%	61 min	1.34%	A
SEA to SJC · San Jose	1,562	88.0%	61 min	0.19%	A+
SEA to PSC · Pasco	1,542	84.9%	66 min	0.71%	B+
SEA to RDM · Redmond	1,415	86.6%	52 min	1.70%	A
SEA to BLI · Bellingham	1,247	84.5%	51 min	2.25%	B
SEA to MFR · Medford	1,243	88.2%	64 min	0.97%	A+
SEA to LAX · Los Angeles	1,241	86.3%	109 min	0.64%	A+
SEA to ONT · Ontario	1,084	89.7%	52 min	0.37%	A+
SEA to SFO · San Francisco	1,081	75.4%	53 min	1.02%	B
SEA to BZN · Bozeman	948	87.4%	51 min	0.21%	A+
SEA to FAT · Fresno	588	83.6%	51 min	0.68%	B+
SEA to PHX · Phoenix	506	80.2%	75 min	0.59%	B+
SEA to SLC · Salt Lake City	418	81.3%	49 min	0.00%	B+
SEA to PSP · Palm Springs	417	83.5%	53 min	0.72%	B+
SEA to SNA · Santa Ana	405	82.4%	36 min	0.25%	B+
SEA to TUS · Tucson	371	83.0%	52 min	0.00%	B+
SEA to LWS · Lewistonthin sample	364	92.3%	60 min	0.27%	A+
SEA to IDA · Idaho Fallsthin sample	305	81.1%	50 min	0.33%	B+
SEA to DEN · Denverthin sample	221	85.0%	60 min	0.45%	A+
SEA to JAC · Jacksonthin sample	203	91.0%	61 min	0.00%	A+
SEA to RDD · Reddingthin sample	144	81.2%	62 min	0.00%	B+

Departure window

Best time of day for this operation

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 29,000 flights.

5am–8am2,314 flights90.3%
8am–11am6,118 flights89.4%
11am–2pm4,989 flights83.4%
2pm–5pm5,412 flights84.8%
5pm–8pm4,538 flights82.9%
8pm–5am5,738 flights86.8%

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

The early departures do better, though not dramatically: 90.3% on time for the 5am–8am window against 82.9% for 5pm–8pm. Worth taking if the schedule allows, not worth an extra connection. The 8am–11am window is the busiest, with 6,118 flights scheduled in it.

Across the year

Seasonal pattern

Darker means more delays. Figures are on-time percentages.October best, December worst

December is the weak month at 82.2% on time, against 89.5% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 2,876 flights.

Delay causes

What holds this operation up

Carrier
50%
Extreme weather
19%
Late-arriving aircraft
18%
National Airspace System
13%
Security
0%

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 monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.0 times the usual weather exposure. The split is drawn from 232,983 reported delay minutes.

Cancellations are rare at 0.71%, 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.

Badly late arrivals are rare here: only 3.9% 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.

29,109 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.

Put together: take the 5am–8am departure, avoid December if the dates are flexible, and if two carriers are within a few dollars of each other, Envoy is the one with the record behind it. None of that guarantees an on-time arrival; it moves the odds by 27 points, which is the most any booking decision can do. 28,865 completed flights over 12 months sit behind that.

Common questions

SkyWest Airlines at SEA

How often is SkyWest Airlines at SEA delayed?

About one flight in seven arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 13.9% of the 29,109 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on SkyWest Airlines at SEA?

Envoy Air leads at 86.9% on time across 691 flights. JetBlue Airways is at the other end on 59.6%, a gap of 27 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on SkyWest Airlines at SEA?

The 5am–8am departure window is the strongest at 90.3% on time. The 5pm–8pm window is the weakest at 82.9%, 7 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are December delays on SkyWest Airlines at SEA?

December is the weakest month at 82.2% on time, compared with 89.5% in October. Across the year that is 7 points between the best and worst months. The seasonal swing is modest enough that it should not decide when you travel.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures