Route reliability record
LAS→SEA
Las Vegas to Seattle
- Flights
- 5,617
- Period
- September 2025 to August 2026
- Distance
- 867 mi
- Carriers
- 5
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 5,617 LAS to SEA flights, of which Delta Air Lines flew 1,748 at 87.2% on time.
Best time to fly LAS to SEA: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 90.3% of the time and Tuesday flights 86.5%, against 82.1% for the route overall.
Delta Air Lines is the most reliable of the three carriers covered here at 87.2% on time across 1,748 flights.
Key figures
On time
82.1%
Arrivals under 15 minutes late, of 5,554 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
1.00%
National rate is 1.89%
Best carrier
Delta
87.2% on time across 1,748 flights
These figures cover 5,617 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on LAS to SEA
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 87.2% of the time; Southwest Airlines manages 70.9%. Sample sizes sit next to every figure, because a two-point gap across 978 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 1,748 | 87.2% | 90 min | 1.09% | A |
| SkyWest Airlinesthin sample | 7 | 85.7% | 59 min | 0.00% | A+ |
| Alaska Airlines | 2,610 | 83.2% | 66 min | 1.19% | B |
| Frontier Airlinesthin sample | 274 | 80.3% | 47 min | 1.09% | B |
| Southwest Airlines | 978 | 70.9% | 45 min | 0.31% | C+ |
The spread between Delta and Southwest is 16 points, wide enough that it should decide the booking. On a hundred trips that is 16 more arrivals inside the on-time window.
Flight by flight
Flights on LAS 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.
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Best ways to make this trip
The most reliable ways to fly Las Vegas to Seattle
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. LAS → SEALas Vegas to Seattle | Delta Air Lines | 86.2% | 87.2% | 1.09% | 8am–11am, Wed | DL 2844 06:00 |
| 2. LAS → SEALas Vegas to Seattle | Alaska Airlines | 82.2% | 83.2% | 1.19% | 5am–8am, Tue | AS 701 06:00 |
| 3. LAS → SEALas Vegas to Seattle | Southwest Airlines | 70.7% | 70.9% | 0.31% | 8am–11am, Tue | — |
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 19 points, against 16 points between the best and worst carrier.
- 5am–8am1,130 flights90.3%
- 8am–11am823 flights85.2%
- 11am–2pm1,262 flights86.5%
- 2pm–5pm1,031 flights76.5%
- 5pm–8pm906 flights74.9%
- 8pm–5am465 flights71.7%
Scale runs 65% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.3% of the time, against 71.7% for the overnight window. That is 19 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 1,262 flights scheduled in it.
Explore
Filter LAS 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 LAS to SEA, the best departure window is 5am–8am at 90.3% on time and the worst is 8pm–5am at 71.7%, a wide gap of 18.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am90.3%
- 8–11am85.2%
- 11am–2pm86.5%
- 2–5pm76.5%
- 5–8pm74.9%
- 8pm–5am71.7%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 20 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 73.7% on time, 20 points below February, the best at 93.4%. 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 496 flights.
Across the week, Tuesday is the strongest day at 86.5% on time and Friday the weakest at 75.3%, a spread of 11 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 47% of the 64,000 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Late-arriving aircraft
- 36%Carrier
- 14%National Airspace System
- 3%Extreme weather
- 0%Security
47% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 64,000 reported delay minutes here, that single category outweighs weather by 17 to one. The split is drawn from 63,796 reported delay minutes.
The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 23,000 of the 64,000 delay minutes reported here.
Cancellations sit at 1.00% against a national 1.89%, which is ordinary. Diversions add another 0.12%.
Connections and stage length
What a delay here actually costs
5.1% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
The 867 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 77.6% on time across 5,620 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.
The sample behind these figures is 5,617 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. February runs 93.4% on time and August 73.7%, a swing of 20 points. If the dates move at all, move them out of August before you think about anything else. 5,554 completed flights over 12 months sit behind that.
Common questions
LAS to SEA questions
How often is LAS to SEA 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 17.9% of the 5,617 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on LAS to SEA?
Delta Air Lines leads at 87.2% on time across 1,748 flights. Southwest Airlines is at the other end on 70.9%, a gap of 16 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 LAS to SEA?
The 5am–8am departure window is the strongest at 90.3% on time. The 8pm–5am window is the weakest at 71.7%, 19 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 LAS to SEA?
August is the weakest month at 73.7% on time, compared with 93.4% in February. Across the year that is 20 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 LAS — the return legseparate record
- Harry Reid International (LAS) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on LAS to SEA87.2%
- Alaska Airlines on LAS to SEA83.2%
- Frontier Airlines on LAS to SEA80.3%
- Southwest Airlines on LAS to SEA70.9%
- LAS to LAX, a related route77.9%
- LAX to SEA, a related route85.0%
- LAS to DEN, a related route76.5%
- Delta Air Lines on-time record87.2%
- SkyWest Airlines on-time record85.7%
- Alaska Airlines on-time record83.2%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. LAS to SEA and SEA to LAS 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.