Carrier route record

UASEA→LAX

United Airlines · Seattle to Los Angeles

Flights: 393
Period: July 2025 to June 2026
Share of route: 5%
Carriers: 6

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

United on SEA to LAX earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 13 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 393 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 1,241 at 86.3% on time.

Set against the rest of the country, United's SEA to LAX record is 13 points better than the US average of 77.6%. That gap is worth roughly 127 fewer late arrivals for every thousand flights.

On time

90.3%

Arrivals under 15 minutes late, of 393 completed flights

Avg delay

98 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

Whole route

83.4%

Every carrier on SEA to LAX, 7,428 flights

These figures cover 393 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

United against every carrier on SEA to LAX

United flew 393 of the 7,428 flights on SEA to LAX, about 5% of it. Its 90.3% on time is 7 points better than the route as a whole, which runs 83.4%. Ranked by on-time rate it is number two of six carriers on the route, where the range runs from American at 90.9% to Frontier at 78.9%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The three carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.

On-time performance by carrier on SEA to LAX
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlinesthin sample	11	90.9%	149 min	0.00%	A+
United Airlines (this page)	393	90.3%	98 min	0.00%	A+
SkyWest Airlines	1,241	86.3%	109 min	0.64%	A+
Delta Air Lines	2,225	84.5%	59 min	0.67%	B+
Alaska Airlines	3,282	81.0%	43 min	1.07%	B
Frontier Airlinesthin sample	276	78.9%	60 min	3.62%	B−

No carrier stands out. SkyWest tops the table at 86.3%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.

Departure window

When United 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 393 flights.

5am–8am171 flights94.2%
8am–11am11 flights—
11am–2pm36 flights94.4%
2pm–5pm—
5pm–8pm175 flights85.7%
8pm–5am—

Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 11am–2pm slot at 94.4% on time, ahead of 5pm–8pm at 85.7%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 5pm–8pm window is the busiest, with 175 flights scheduled in it.

Across the year

United on SEA to LAX through the year

Jul–Sep 2025183 flights86.9%
Oct–Dec 202586 flights95.3%
Jan–Mar 20262 flights—
Apr–Jun 2026122 flights91.8%

Scale runs 80% to 100%. 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 90.3% on time across 393 flights.

Quarter by quarter United on SEA to LAX held fairly steady: 86.9% in Jul–Sep 2025, 95.3% in Oct–Dec 2025 and 91.8% in Apr–Jun 2026. A spread of 8 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Across the week, Friday is the strongest day at 94.6% on time and Wednesday the weakest at 86.0%. 9 points is a smaller lever than departure hour, but it is free.

Delay causes

Why United runs late on this route

One category carries most of the weight here. Carrier accounts for 61% of the 3,706 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
61%
Late-arriving aircraft
33%
National Airspace System
6%

The largest share of delay minutes, 61%, 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 2,259 of the 3,706 delay minutes reported here. The split is drawn from 3,706 reported delay minutes.

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 stage length

What a delay here costs

5.1% 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 an hour and a half, which a normal layover absorbs.

The 954 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 85.0% on time across 395 flights, 5 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 5 points of difference.

One caution: this is a thin sample. 393 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 United on SEA to LAX

Put together: treat all of this as provisional. 393 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 90.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 393 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