Carrier route record

ASMCI→SEA

Alaska Airlines · Kansas City to Seattle

Flights: 745
Period: July 2025 to June 2026
Share of route: 66%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Alaska Airlines.

Alaska on MCI to SEA lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 745 flights, with a median arrival 5 minutes early.

Set against the rest of the country, Alaska's MCI to SEA record is 5 points better than the US average of 77.6%. That gap is worth roughly 54 fewer late arrivals for every thousand flights.

On time

83.0%

Arrivals under 15 minutes late, of 737 completed flights

Avg delay

67 min

Across delayed arrivals only, not all flights

Cancelled

0.81%

National rate is 1.81%

Whole route

83.4%

Every carrier on MCI to SEA, 1,131 flights

These figures cover 745 flights between July 2025 and June 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.

Carrier by carrier

Alaska against every carrier on MCI to SEA

Alaska flew 745 of the 1,131 flights on MCI to SEA, most of the route. Its 83.0% on time is about level with the route as a whole at 83.4%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from Delta at 85.3% to Southwest at 63.6%. 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.

On-time performance by carrier on MCI to SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Linesthin sample	364	85.3%	84 min	1.65%	A
Alaska Airlines (this page)	745	83.0%	67 min	0.81%	B+
Southwest Airlinesthin sample	22	63.6%	66 min	0.00%	D+

Flight by flight

Alaska flight numbers on MCI to SEA

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 24 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am282 flights90.7%
8am–11am—
11am–2pm—
2pm–5pm343 flights82.3%
5pm–8pm1 flights—
8pm–5am119 flights66.9%

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 90.7% of the time, against 66.9% for the overnight window. That is 24 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 343 flights scheduled in it.

Across the year

Alaska on MCI to SEA through the year

Darker means more delays. Figures are on-time percentages.May best, December worst

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. June was the busiest month here, with 89 flights.

Across the week, Tuesday is the strongest day at 88.3% on time and Sunday the weakest at 76.3%. 12 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Alaska runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 44% of the 8,308 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.

Late-arriving aircraft
44%
Carrier
30%
National Airspace System
21%
Extreme weather
4%

44% 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 8,308 reported delay minutes here, that single category outweighs weather by 11 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 split is drawn from 8,308 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 90.7% on time here.

Cancellations are rare at 0.81%, below the national 1.81% 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 4.7% land an hour or more behind schedule, against 8.1% 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. 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 79.3% on time across 745 flights, 4 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 4 points of difference.

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 83.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 737 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures