Carrier route record

DLLAX→SEA

Delta Air Lines · Los Angeles to Seattle

Flights: 2,224
Period: July 2025 to June 2026
Share of route: 30%
Carriers: 6

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

Delta 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 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 2,224 flights. The strongest carrier on the route with a full sample, Alaska Airlines, flew 3,279 at 85.2% on time.

Set against the rest of the country, Delta's LAX to SEA record is 9 points better than the US average of 77.6%. That gap is worth roughly 92 fewer late arrivals for every thousand flights.

On time

86.8%

Arrivals under 15 minutes late, of 2,203 completed flights

Avg delay

76 min

Across delayed arrivals only, not all flights

Cancelled

0.76%

National rate is 1.81%

Whole route

85.4%

Every carrier on LAX to SEA, 7,424 flights

These figures cover 2,224 flights between July 2025 and June 2026. The median arrival is 15 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

Delta against every carrier on LAX to SEA

Delta flew 2,224 of the 7,424 flights on LAX to SEA, about 30% of it. Its 86.8% on time is about level with the route as a whole at 85.4%. Ranked by on-time rate it is first 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: half a point 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 (this page)	2,224	86.8%	76 min	0.76%	A+
Alaska Airlines	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. Alaska tops the table at 85.2%, half a point clear of the bottom, which is inside the range this kind of sample moves year to year.

Flight by flight

Delta flight numbers on LAX to SEA

Departure window

When Delta 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 2,224 flights.

5am–8am339 flights92.2%
8am–11am374 flights92.2%
11am–2pm350 flights88.2%
2pm–5pm377 flights83.3%
5pm–8pm480 flights83.0%
8pm–5am304 flights83.0%

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

Book the early departure. Flights leaving between 5am–8am arrive on time 92.2% of the time, against 83.0% for the overnight window. That is 9 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 480 flights scheduled in it.

Across the year

Delta on LAX to SEA through the year

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

June is the worst month at 80.1% on time, 14 points below September, the best at 94.3%. 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. May was the busiest month here, with 204 flights.

Across the week, Saturday is the strongest day at 90.3% on time and Sunday the weakest at 81.1%. 9 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 66% of the 22,000 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
66%
Late-arriving aircraft
28%
National Airspace System
5%
Security
0%

The largest share of delay minutes, 66%, 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 14,000 of the 22,000 delay minutes reported here. The split is drawn from 21,966 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 92.2% on time here.

Cancellations are rare at 0.76%, 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

5.2% 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 a little over an hour, 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 runs 84.5% on time across 2,225 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 2,224 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 Delta on LAX to SEA

Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 94.3% on time and June 80.1%, a swing of 14 points. If the dates move at all, move them out of June before you think about anything else. 2,203 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