Carrier route record

ASLAX→SEA

Alaska Airlines · Los Angeles to Seattle

Flights: 3,279
Period: July 2025 to June 2026
Share of route: 44%
Carriers: 6

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

Alaska on LAX to SEA 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 8 points better than the national rate of 77.6%. When something does go wrong the average delay runs about 50 minutes. That rests on 3,279 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 2,224 at 86.8% on time.

Delta Air Lines is the most reliable of the three carriers covered here at 86.8% on time across 2,224 flights.

On time

85.2%

Arrivals under 15 minutes late, of 3,241 completed flights

Avg delay

49 min

Across delayed arrivals only, not all flights

Cancelled

1.10%

National rate is 1.81%

Whole route

85.4%

Every carrier on LAX to SEA, 7,424 flights

These figures cover 3,279 flights between July 2025 and June 2026. The median arrival is 9 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

Alaska against every carrier on LAX to SEA

Alaska flew 3,279 of the 7,424 flights on LAX to SEA, about 44% of it. Its 85.2% on time is about level with the route as a whole at 85.4%. Ranked by on-time rate it is number two of six carriers on the route, where the range runs from Delta at 86.8% to Frontier at 79.7%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The three carriers here are closely matched: 2 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 LAX to SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	2,224	86.8%	76 min	0.76%	A+
Alaska Airlines (this page)	3,279	85.2%	49 min	1.10%	A
United Airlines	395	85.0%	47 min	0.51%	A+
SkyWest Airlines	1,239	84.6%	82 min	0.65%	B+
American Airlinesthin sample	11	81.8%	159 min	0.00%	B+
Frontier Airlinesthin sample	276	79.7%	76 min	3.62%	B−

No carrier stands out. Delta tops the table at 86.8%, 2 points clear of the bottom, which is inside the range this kind of sample moves year to year.

Flight by flight

Alaska flight numbers on LAX to SEA

Departure window

When Alaska runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 11 points, against 2 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am477 flights89.5%
8am–11am604 flights85.6%
11am–2pm391 flights78.6%
2pm–5pm652 flights86.1%
5pm–8pm815 flights85.7%
8pm–5am340 flights82.6%

Scale runs 70% 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 78.6% on time against 89.5% for 5am–8am. 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 5pm–8pm window is the busiest, with 815 flights scheduled in it.

Across the year

Alaska on LAX to SEA through the year

Darker means more delays. Figures are on-time percentages.September best, July worst

July is the worst month at 75.8% on time, 17 points below September, the best at 93.0%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 305 flights.

Across the week, Monday is the strongest day at 89.1% on time and Friday the weakest at 78.3%. 11 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Alaska runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 24,000 reported delay minutes.

Carrier
40%
Late-arriving aircraft
32%
National Airspace System
25%
Extreme weather
2%
Security
0%

The largest share of delay minutes, 40%, 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 9,598 of the 24,000 delay minutes reported here. The split is drawn from 23,704 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 89.5% on time here.

Cancellations sit at 1.10% against a national 1.81%, which is ordinary. Diversions add another 0.06%.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 3.4% 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 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 81.0% on time across 3,282 flights, 4 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 4 points of difference.

The sample behind these figures is 3,279 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking Alaska on LAX to SEA

Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 93.0% on time and July 75.8%, a swing of 17 points. If the dates move at all, move them out of July before you think about anything else. 3,241 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