Route reliability record
SEA→LAX
Seattle to Los Angeles
- Flights
- 7,536
- Period
- September 2025 to August 2026
- Distance
- 954 mi
- Carriers
- 6
This route lands a B+, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 7,536 SEA to LAX flights, of which United Airlines flew 375 at 88.8% on time.
Best time to fly SEA to LAX: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 87.5% of the time and Tuesday flights 85.9%, against 82.0% for the route overall.
United Airlines is the most reliable of the four carriers covered here at 88.8% on time across 375 flights.
Key figures
On time
82.0%
Arrivals under 15 minutes late, of 7,471 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
0.81%
National rate is 1.89%
Best carrier
United
88.8% on time across 375 flights
These figures cover 7,536 flights between September 2025 and August 2026. The median arrival is 6 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 SEA to LAX
The choice of carrier is not cosmetic here. United Airlines arrives on time 88.8% of the time; Alaska Airlines manages 80.4%. Sample sizes sit next to every figure, because a two-point gap across 3,293 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 375 | 88.8% | 72 min | 0.00% | A+ |
| American Airlinesthin sample | 15 | 86.7% | 134 min | 0.00% | A+ |
| SkyWest Airlines | 1,316 | 85.0% | 112 min | 0.68% | A+ |
| Delta Air Lines | 2,229 | 81.6% | 59 min | 0.58% | B+ |
| Alaska Airlines | 3,293 | 80.4% | 42 min | 0.91% | B+ |
| Frontier Airlinesthin sample | 308 | 79.9% | 59 min | 2.92% | B |
United leads Alaska by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on SEA to LAX
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 276910:1583.8% · 365 flights
- Delta 286117:5974.2% · 365 flights
- Delta 162807:1590.6% · 361 flights
- Delta 283013:3083.8% · 349 flights
- Alaska 50506:0382.8% · 339 flights
- Delta 291412:4584.0% · 327 flights
- Delta 285419:5974.8% · 320 flights
- Alaska 130015:5974.7% · 302 flights
- Alaska 69613:3879.0% · 277 flights
- Alaska 52418:1078.9% · 276 flights
- Alaska 130608:0089.5% · 261 flights
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Best ways to make this trip
The most reliable ways to fly Seattle to Los Angeles
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. 3 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SEA → LAXSeattle to Los Angeles | United Airlines | 88.8% | 88.8% | 0.00% | 11am–2pm, Fri | — |
| 2. SEA → ONTSeattle to Ontario | SkyWest Airlines | 88.0% | 88.3% | 0.38% | 8am–11am, Sat | OO 4031 14:30 |
| 3. SEA → SNASeattle to Santa Ana | Alaska Airlines | 85.5% | 86.3% | 0.93% | 5am–8am, Tue | AS 699 07:15 |
| 4. SEA → LAXSeattle to Los Angeles | SkyWest Airlines | 84.4% | 85.0% | 0.68% | 11am–2pm, Tue | — |
| 5. SEA → SNASeattle to Santa Ana | Delta Air Lines | 81.6% | 82.4% | 1.01% | 5am–8am, Sat | — |
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 matters more here than the choice of carrier. The gap between the best and worst window is 14 points, against 8 points between the best and worst carrier.
- 5am–8am1,469 flights87.5%
- 8am–11am1,162 flights85.7%
- 11am–2pm1,330 flights82.5%
- 2pm–5pm994 flights80.6%
- 5pm–8pm1,634 flights79.8%
- 8pm–5am947 flights73.5%
Scale runs 65% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 87.5% of the time, against 73.5% for the overnight window. That is 14 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 1,634 flights scheduled in it.
Explore
Filter SEA to LAX 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 SEA to LAX, the best departure window is 5am–8am at 87.5% on time and the worst is 8pm–5am at 73.5%, a wide gap of 14.0 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am87.5%
- 8–11am85.7%
- 11am–2pm82.5%
- 2–5pm80.6%
- 5–8pm79.8%
- 8pm–5am73.5%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 19 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.
July is the worst month at 70.2% on time, 19 points below April, the best at 89.5%. 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 85.9% on time and Thursday the weakest at 78.7%, a spread of 7 points.
Delay causes
Why this route gets delayed
Carrier accounts for 49% of the 80,000 delay minutes carriers reported here, and the remaining four split what is left.
- 49%Carrier
- 32%Late-arriving aircraft
- 15%National Airspace System
- 3%Extreme weather
The largest share of delay minutes, 49%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 39,000 of the 80,000 delay minutes reported here. The split is drawn from 79,834 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 87.5% on time here.
Cancellations are rare at 0.81%, 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 85.0% on time across 7,534 flights, 3 points above 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 7,536 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 LAX 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. April runs 89.5% on time and July 70.2%, a swing of 19 points. If the dates move at all, move them out of July before you think about anything else. 7,471 completed flights over 12 months sit behind that.
Common questions
SEA to LAX questions
How often is SEA to LAX delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.0% of the 7,536 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SEA to LAX?
United Airlines leads at 88.8% on time across 375 flights. Alaska Airlines is at the other end on 80.4%, a gap of 8 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 SEA to LAX?
The 5am–8am departure window is the strongest at 87.5% on time. The 8pm–5am window is the weakest at 73.5%, 14 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 July delays on SEA to LAX?
July is the weakest month at 70.2% on time, compared with 89.5% in April. Across the year that is 19 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
- LAX to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Los Angeles International (LAX) delay statistics
- United Airlines on SEA to LAX88.8%
- SkyWest Airlines on SEA to LAX85.0%
- Delta Air Lines on SEA to LAX81.6%
- Alaska Airlines on SEA to LAX80.4%
- Frontier Airlines on SEA to LAX79.9%
- SEA to PHX, a related route78.2%
- SFO to LAX, a related route70.9%
- SEA to SFO, a related route59.8%
- United Airlines on-time record88.8%
- American Airlines on-time record86.7%
- SkyWest Airlines on-time record85.0%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SEA to LAX and LAX to SEA 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.