Route reliability record
LAX→SEA
Los Angeles to Seattle
- Flights
- 7,534
- Period
- September 2025 to August 2026
- Distance
- 954 mi
- Carriers
- 6
This route 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 77.3%. When something does go wrong the average delay runs about an hour. That rests on 7,534 LAX to SEA flights, of which United Airlines flew 376 at 89.1% on time.
Best time to fly LAX to SEA: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 91.4% of the time and Tuesday flights 88.7%, against 85.0% for the route overall.
United Airlines is the most reliable of the four carriers covered here at 89.1% on time across 376 flights.
Key figures
On time
85.0%
Arrivals under 15 minutes late, of 7,462 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
0.84%
National rate is 1.89%
Best carrier
United
89.1% on time across 376 flights
These figures cover 7,534 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on LAX to SEA
The four carriers here are closely matched: 6 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 376 | 89.1% | 40 min | 0.00% | A+ |
| Delta Air Lines | 2,228 | 85.2% | 71 min | 0.67% | A+ |
| Alaska Airlines | 3,292 | 85.2% | 52 min | 0.88% | A+ |
| Frontier Airlinesthin sample | 308 | 83.5% | 62 min | 3.25% | B− |
| SkyWest Airlines | 1,315 | 83.4% | 72 min | 0.68% | B+ |
| American Airlinesthin sample | 15 | 73.3% | 142 min | 0.00% | C+ |
No carrier stands out. United tops the table at 89.1%, 6 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on LAX to SEA
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
- Delta 260614:0083.1% · 365 flights
- Delta 298007:0092.2% · 364 flights
- Delta 264017:4581.8% · 361 flights
- Delta 171409:4591.7% · 329 flights
- Delta 104511:5086.9% · 323 flights
- Alaska 130512:4773.3% · 312 flights
- Frontier 117715:0483.6% · 303 flights
- Alaska 130118:0986.8% · 302 flights
- Delta 155119:5977.9% · 301 flights
- Alaska 58513:5984.8% · 291 flights
- Alaska 79810:0086.5% · 261 flights
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Best ways to make this trip
The most reliable ways to fly Los Angeles to Seattle
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. ONT → SEAOntario to Seattle | SkyWest Airlines | 91.4% | 91.7% | 0.28% | 2pm–5pm, Sat | OO 4031 17:50 |
| 2. LAX → SEALos Angeles to Seattle | United Airlines | 89.1% | 89.1% | 0.00% | 8am–11am, Sat | — |
| 3. SNA → SEASanta Ana to Seattle | Alaska Airlines | 86.9% | 87.9% | 1.13% | 8pm–5am, Wed | AS 1325 06:45 |
| 4. LAX → SEALos Angeles to Seattle | Delta Air Lines | 84.6% | 85.2% | 0.67% | 5am–8am, Tue | DL 2980 07:00 |
| 5. LAX → SEALos Angeles to Seattle | Alaska Airlines | 84.5% | 85.2% | 0.88% | 5am–8am, Mon | AS 1301 18:09 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
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 7,534 flights.
- 5am–8am826 flights91.4%
- 8am–11am1,356 flights88.0%
- 11am–2pm1,198 flights83.9%
- 2pm–5pm1,586 flights83.6%
- 5pm–8pm1,787 flights82.5%
- 8pm–5am781 flights83.2%
Scale runs 75% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.4% of the time, against 82.5% for the evening 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 1,787 flights scheduled in it.
Explore
Filter LAX to SEA by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On LAX to SEA, the best departure window is 5am–8am at 91.4% on time and the worst is 5pm–8pm at 82.5%, a real gap of 8.9 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am91.4%
- 8–11am88.0%
- 11am–2pm83.9%
- 2–5pm83.6%
- 5–8pm82.5%
- 8pm–5am83.2%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 15 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 77.9% on time, 15 points below September, the best at 92.5%. 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. August was the busiest month here, with 717 flights.
Across the week, Tuesday is the strongest day at 88.7% on time and Friday the weakest at 82.2%, a spread of 7 points.
Delay causes
Why this route gets delayed
Carrier accounts for 49% of the 69,000 delay minutes carriers reported here, and the remaining four split what is left.
- 49%Carrier
- 37%Late-arriving aircraft
- 13%National Airspace System
- 1%Extreme weather
- 0%Security
37% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 69,000 reported delay minutes here, that single category outweighs weather by 33 to one. The split is drawn from 68,862 reported delay minutes.
The largest share of delay minutes, 49%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 34,000 of the 69,000 delay minutes reported here.
Cancellations are rare at 0.84%, below the national 1.89% 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 actually costs
Badly late arrivals are rare here: only 4.6% land an hour or more behind schedule, against 8.3% 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.
The return leg is a different operation and performs like one: it runs 82.0% on time across 7,536 flights, 3 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 3 points of difference.
The sample behind these figures is 7,534 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.
Work out the risk of missing a connection in SEA after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 92.5% on time and August 77.9%, a swing of 15 points. If the dates move at all, move them out of August before you think about anything else. 7,462 completed flights over 12 months sit behind that.
Common questions
LAX to SEA questions
How often is LAX to SEA delayed?
About one flight in seven arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 15.0% of the 7,534 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on LAX to SEA?
United Airlines leads at 89.1% on time across 376 flights. SkyWest Airlines is at the other end on 83.4%, a gap of 6 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 LAX to SEA?
The 5am–8am departure window is the strongest at 91.4% on time. The 5pm–8pm window is the weakest at 82.5%, 9 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 August delays on LAX to SEA?
August is the weakest month at 77.9% on time, compared with 92.5% in September. Across the year that is 15 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SEA to LAX — the return legseparate record
- Los Angeles International (LAX) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- United Airlines on LAX to SEA89.1%
- Delta Air Lines on LAX to SEA85.2%
- Alaska Airlines on LAX to SEA85.2%
- Frontier Airlines on LAX to SEA83.5%
- SkyWest Airlines on LAX to SEA83.4%
- LAX to SFO, a related route60.1%
- PHX to SEA, a related route82.2%
- LAX to JFK, a related route77.5%
- United Airlines on-time record89.1%
- Delta Air Lines on-time record85.2%
- Alaska Airlines on-time record85.2%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. LAX to SEA and SEA to LAX are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.