Route reliability record
SEA→KOA
Seattle to Kailua-Kona
- Flights
- 1,410
- Period
- September 2025 to August 2026
- Distance
- 2,688 mi
- Carriers
- 2
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 77.3%. The late ones land about 50 minutes behind schedule. That rests on 1,410 SEA to KOA flights, of which Delta Air Lines flew 365 at 76.1% on time.
Best time to fly SEA to KOA: a 2pm–5pm departure, ideally on a Wednesday. Flights in that window arrived on time 78.4% of the time and Wednesday flights 80.6%, against 74.5% for the route overall.
The US average over the same twelve months is 77.3%, 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
74.5%
Arrivals under 15 minutes late, of 1,376 completed flights
Avg delay
50 min
Across delayed arrivals only, not all flights
Cancelled
1.42%
National rate is 1.89%
Best carrier
Delta
76.1% on time across 365 flights
These figures cover 1,410 flights between September 2025 and August 2026. The median arrival is 5 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Which airline is most reliable on SEA to KOA
The two carriers here are closely matched: 2 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 | 365 | 76.1% | 47 min | 2.19% | B |
| Alaska Airlines | 1,045 | 73.9% | 51 min | 1.15% | C |
No carrier stands out. Delta tops the table at 76.1%, 2 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on SEA to KOA
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.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Best ways to make this trip
The most reliable ways to fly Seattle to Kailua-Kona
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. SEA → KOASeattle to Kailua-Kona | Delta Air Lines | 74.4% | 76.1% | 2.19% | 2pm–5pm, Wed | DL 340 14:30 |
| 2. SEA → KOASeattle to Kailua-Kona | Alaska Airlines | 73.1% | 73.9% | 1.15% | 2pm–5pm, Mon | AS 238 15:59 |
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 1,410 flights.
- 5am–8am1 flights—
- 8am–11am266 flights72.1%
- 11am–2pm296 flights71.5%
- 2pm–5pm536 flights78.4%
- 5pm–8pm311 flights72.4%
- 8pm–5am—
Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 71.5% on time against 78.4% for 2pm–5pm. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 2pm–5pm window is the busiest, with 536 flights scheduled in it.
Explore
Filter SEA to KOA 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 KOA, the best departure window is 2pm–5pm at 78.4% on time and the worst is 11am–2pm at 71.5%, a real gap of 6.9 points. All US flights leaving 2pm–5pm ran 71.9%.
- 5–8am—
- 8–11am72.1%
- 11am–2pm71.5%
- 2–5pm78.4%
- 5–8pm72.4%
- 8pm–5am—
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 37 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.
April is the best month on the calendar at 93.7% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. January was the busiest month here, with 124 flights.
Across the week, Wednesday is the strongest day at 80.6% on time and Friday the weakest at 67.2%, a spread of 13 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 17,000 reported delay minutes.
- 38%Carrier
- 31%National Airspace System
- 29%Late-arriving aircraft
- 2%Extreme weather
The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 6,700 of the 17,000 delay minutes reported here. The split is drawn from 17,447 reported delay minutes.
Cancellations sit at 1.42% against a national 1.89%, which is ordinary. Diversions add another 0.99%.
Connections and stage length
What a delay here actually costs
6.0% 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 50 minutes, which a normal layover absorbs.
At 2,688 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 86.7% on time across 1,412 flights, 12 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 12 points of difference.
The sample behind these figures is 1,410 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 KOA 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 93.7% on time and March 57.0%, a swing of 37 points. If the dates move at all, move them out of March before you think about anything else. 1,376 completed flights over 12 months sit behind that.
Common questions
SEA to KOA questions
How often is SEA to KOA delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 25.5% of the 1,410 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 50 minutes on average.
Which airline is most reliable on SEA to KOA?
Delta Air Lines leads at 76.1% on time across 365 flights. Alaska Airlines is at the other end on 73.9%, a gap of 2 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 KOA?
The 2pm–5pm departure window is the strongest at 78.4% on time. The 11am–2pm window is the weakest at 71.5%, 7 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 March delays on SEA to KOA?
March is the weakest month at 57.0% on time, compared with 93.7% in April. Across the year that is 37 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
- KOA to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on SEA to KOA76.1%
- Alaska Airlines on SEA to KOA73.9%
- SEA to LAX, a related route82.0%
- HNL to KOA, a related route85.3%
- SEA to PHX, a related route78.2%
- Delta Air Lines on-time record76.1%
- Alaska Airlines on-time record73.9%
- Worst months to fly in the US, ranked by the data
- Does flight distance affect delays? Less than it affects cancellations
Direction matters. SEA to KOA and KOA to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Embed SEA to KOA’s on-time badge on your site
Paste this into a web page. The badge shows the current on-time rate, cancellation rate and grade, and updates every month. Preview it, or build a badge for another route or airport.
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.