Route reliability record
SEA→ANC
Seattle to Anchorage
- Flights
- 6,717
- Period
- June 2025 to May 2026
- Distance
- 1,448 mi
- Carriers
- 3
This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.4%. The late ones land about 50 minutes behind schedule. That rests on 6,717 flights, of which Delta Air Lines flew 1,643 at 78.9% on time.
The US average over the same twelve months is 77.4%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
74.2%
Arrivals under 15 minutes late, of 6,645 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
1.01%
National rate is 1.80%
Best carrier
Delta
78.9% on time across 1,643 flights
These figures cover 6,717 flights between June 2025 and May 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Which airline is most reliable on SEA to ANC
The two 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 |
|---|---|---|---|---|---|
| Delta Air Lines | 1,643 | 78.9% | 61 min | 0.61% | B+ |
| Alaska Airlines | 4,913 | 73.3% | 47 min | 1.14% | C |
| Hawaiian Airlinesthin sample | 161 | 54.7% | 62 min | 1.24% | F |
No carrier stands out. Delta tops the table at 78.9%, 6 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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 16 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am544 flights87.3%
- 8am–11am1,268 flights76.3%
- 11am–2pm1,216 flights71.5%
- 2pm–5pm690 flights75.4%
- 5pm–8pm1,063 flights71.0%
- 8pm–5am1,936 flights72.3%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 87.3% of the time, against 71.0% for the evening window. That is 16 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.
Across the year
When delays peak on this route
This route's year swings by 34 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.
December is the weak month at 54.6% on time, against 88.4% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days.
Across the week, Tuesday is the strongest day at 79.5% on time and Friday the weakest at 70.4%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 50% of the 87,000 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.
- 50%Carrier
- 26%Late-arriving aircraft
- 22%National Airspace System
- 2%Extreme weather
- 0%Security
The largest share of delay minutes, 50%, 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 44,000 of the 87,000 delay minutes reported here.
Cancellations sit at 1.01% against a national 1.80%, which is ordinary. Diversions add another 0.06%.
Connections and stage length
What a delay here actually costs
5.6% of arrivals land an hour or more late, close to the national 8.2%. 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 are the about 50 minutes kind, which a normal layover absorbs.
The 1,448 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 84.8% on time across 6,715 flights, 11 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 11 points of difference.
The sample behind these figures is 6,717 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 this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 88.4% on time and December 54.6%, a swing of 34 points. If the dates move at all, move them out of December before you think about anything else.
Common questions
SEA to ANC questions
How often is SEA to ANC delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 25.8% of the 6,717 flights in this analysis, against 22.6% nationally. Delayed flights are late by about 50 minutes on average.
Which airline is most reliable on SEA to ANC?
Delta Air Lines leads at 78.9% on time across 1,643 flights. Alaska Airlines is at the other end on 73.3%, 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 SEA to ANC?
The 5am–8am departure window is the strongest at 87.3% on time. The 5pm–8pm window is the weakest at 71.0%, 16 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 December delays on SEA to ANC?
December is the weakest month at 54.6% on time, compared with 88.4% in September. Across the year that is 34 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
- ANC to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on-time record78.9%
- Alaska Airlines on-time record73.3%
- Hawaiian Airlines on-time record54.7%
- 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 ANC and ANC to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.