Route reliability record
ANC→SEA
Anchorage to Seattle
- Flights
- 6,715
- Period
- June 2025 to May 2026
- Distance
- 1,448 mi
- Carriers
- 3
This route earns a B. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.4%. When something does go wrong the average delay runs about an hour. That rests on 6,715 flights, of which Delta Air Lines flew 1,642 at 89.3% on time.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.4%. That gap is worth roughly 74 fewer late arrivals for every thousand flights.
Key figures
On time
84.8%
Arrivals under 15 minutes late, of 6,637 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
1.09%
National rate is 1.80%
Best carrier
Delta
89.3% on time across 1,642 flights
These figures cover 6,715 flights between June 2025 and May 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.
Carrier by carrier
Which airline is most reliable on ANC to SEA
The two carriers here are closely matched: 4 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 | 1,642 | 89.3% | 112 min | 0.67% | A+ |
| Alaska Airlines | 4,911 | 85.0% | 53 min | 1.20% | A |
| Hawaiian Airlinesthin sample | 162 | 30.8% | 74 min | 1.85% | F |
No carrier stands out. Delta tops the table at 89.3%, 4 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 13 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,384 flights86.8%
- 8am–11am922 flights89.8%
- 11am–2pm904 flights87.4%
- 2pm–5pm1,167 flights77.1%
- 5pm–8pm696 flights78.6%
- 8pm–5am1,642 flights86.9%
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 89.8% of the time, against 77.1% for the afternoon window. That is 13 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 18 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 77.1% on time, 18 points below April, the best at 94.7%. 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.
The day of the week is close to irrelevant here: 3 points separates the best day from the worst. Weekly demand peaks are not what drives the delays on this operation.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 43% of the 66,000 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.
- 43%Carrier
- 36%Late-arriving aircraft
- 14%National Airspace System
- 7%Extreme weather
- 1%Security
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 66,000 reported delay minutes here, that single category outweighs weather by 5 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit.
The largest share of delay minutes, 43%, 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 28,000 of the 66,000 delay minutes reported here.
Cancellations sit at 1.09% against a national 1.80%, which is ordinary. Diversions add another 0.07%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.3% land an hour or more behind schedule, against 8.2% 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 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 74.2% on time across 6,717 flights, 11 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 11 points of difference.
The sample behind these figures is 6,715 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. April runs 94.7% on time and August 77.1%, a swing of 18 points. If the dates move at all, move them out of August before you think about anything else.
Common questions
ANC to SEA questions
How often is ANC to SEA delayed?
About one flight in seven arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 15.2% of the 6,715 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on ANC to SEA?
Delta Air Lines leads at 89.3% on time across 1,642 flights. Alaska Airlines is at the other end on 85.0%, a gap of 4 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 ANC to SEA?
The 8am–11am departure window is the strongest at 89.8% on time. The 2pm–5pm window is the weakest at 77.1%, 13 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 ANC to SEA?
August is the weakest month at 77.1% on time, compared with 94.7% in April. Across the year that is 18 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 ANC — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on-time record89.3%
- Alaska Airlines on-time record85.0%
- Hawaiian Airlines on-time record30.8%
- 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. ANC to SEA and SEA to ANC 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.