Carrier route record
ASMCI→SEA
Alaska Airlines · Kansas City to Seattle
- Flights
- 745
- Period
- September 2025 to August 2026
- Share of route
- 66%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Alaska Airlines.
Alaska on MCI to SEA 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 77.3%. When something does go wrong the average delay runs about an hour. That rests on 745 flights, with a median arrival 7 minutes early.
Set against the rest of the country, Alaska's MCI to SEA record is 7 points better than the US average of 77.3%. That gap is worth roughly 74 fewer late arrivals for every thousand flights.
Key figures
On time
84.7%
Arrivals under 15 minutes late, of 738 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
0.67%
National rate is 1.89%
Whole route
85.0%
Every carrier on MCI to SEA, 1,126 flights
These figures cover 745 flights between September 2025 and August 2026. The median arrival is 7 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
Alaska against every carrier on MCI to SEA
Alaska flew 745 of the 1,126 flights on MCI to SEA, most of the route. Its 84.7% on time is about level with the route as a whole at 85.0%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from Delta at 87.0% to Southwest at 58.8%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Linesthin sample | 364 | 87.0% | 75 min | 1.65% | A |
| Alaska Airlines (this page) | 745 | 84.7% | 63 min | 0.67% | B+ |
| Southwest Airlinesthin sample | 17 | 58.8% | 37 min | 0.00% | D+ |
Flight by flight
Alaska flight numbers on MCI to SEA
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.
Departure window
When Alaska runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against half a point between the best and worst carrier.
- 5am–8am288 flights90.5%
- 8am–11am—
- 11am–2pm13 flights—
- 2pm–5pm331 flights85.7%
- 5pm–8pm1 flights—
- 8pm–5am112 flights68.5%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.5% of the time, against 68.5% for the overnight window. That is 22 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 331 flights scheduled in it.
Across the year
Alaska on MCI to SEA through the year
December is the weak month at 67.9% on time, against 93.6% in May. 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. July was the busiest month here, with 92 flights.
Across the week, Saturday is the strongest day at 90.1% on time and Friday the weakest at 76.1%, a spread of 14 points.
Arrival by arrival
How late Alaska on MCI to SEA runs when it is late
Alaska on MCI to SEA often beats the schedule: 231 of 738 completed flights, 31%, arrived 15 minutes or more early. The 113 late arrivals split 55 under half an hour, 29 between 30 and 60 minutes, and 29 an hour or more.
- 15+ min early231 flights31.3%
- Within 15 min394 flights53.4%
- 15–29 min late55 flights7.5%
- 30–59 min late29 flights3.9%
- 1–2 hours late17 flights2.3%
- 2+ hours late12 flights1.6%
Scale runs 0% to 100%.
Share of 738 completed flights by arrival against schedule.
14 of 82 late departures made up the time and arrived on time, 17% of them. In the other direction, 45 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SEA.
The worst days
Worst days for Alaska on MCI to SEA
The latest arrival of the period was on 10 April 2026, 9 hours 44 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across April, October, August and March, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 10 April 2026 | 9 hours 44 minutes | Late-arriving aircraft |
| 1 October 2025 | 8 hours 27 minutes | Carrier |
| 19 August 2026 | 8 hours 1 minute | Late-arriving aircraft |
| 6 October 2025 | 5 hours 41 minutes | Carrier |
| 13 March 2026 | 3 hours 36 minutes | Extreme weather |
Delay causes
Why Alaska runs late on this route
Late-arriving aircraft accounts for 43% of the 7,061 delay minutes carriers reported here, and the remaining four split what is left.
- 43%Late-arriving aircraft
- 32%Carrier
- 20%National Airspace System
- 5%Extreme weather
- 0%Security
43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 7,061 reported delay minutes here, that single category outweighs weather by 9 to one. The split is drawn from 7,061 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 90.5% on time here.
Cancellations are rare at 0.67%, 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 costs
Badly late arrivals are rare here: only 3.9% 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 1,490 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 runs 84.3% on time across 745 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 745 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking Alaska on MCI to SEA
Put together: treat all of this as provisional. 745 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 84.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 738 completed flights over 12 months sit behind that.
Related
Where to go next
- MCI to SEA, every carrier
- Alaska on SEA to MCI, the return leg
- Delta Air Lines on MCI to SEA87.0%
- Alaska Airlines network-wide record
- Kansas City International (MCI) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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.