Carrier route record

DLSEA→MCI

Delta Air Lines · Seattle to Kansas City

Flights: 364
Period: July 2025 to June 2026
Share of route: 32%
Carriers: 3

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

Delta on SEA to MCI lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 364 flights, with a median arrival 7 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on SEA to MCI from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

76.6%

Arrivals under 15 minutes late, of 354 completed flights

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

1.65%

National rate is 1.81%

Whole route

77.7%

Every carrier on SEA to MCI, 1,131 flights

These figures cover 364 flights between July 2025 and June 2026. Beyond the headline rate, 8.8% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Delta against every carrier on SEA to MCI

Delta flew 364 of the 1,131 flights on SEA to MCI, about 32% of it. Its 76.6% on time is about level with the route as a whole at 77.7%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from Alaska at 79.3% to Southwest at 45.5%. One 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 SEA to MCI
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlines	745	79.3%	48 min	0.54%	B+
Delta Air Lines (this page)thin sample	364	76.6%	68 min	1.65%	B
Southwest Airlinesthin sample	22	45.5%	55 min	0.00%	F+

Flight by flight

Delta flight numbers on SEA to MCI

DL 225617:5076.6% · 364 flights

Departure window

When Delta runs best on this route

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 364 flights.

There are not enough flights in each departure window to split Delta's SEA to MCI record by time of day without the percentages moving on noise. The headline rate of 76.6% is the reliable figure here.

Across the year

Delta on SEA to MCI through the year

Jul–Sep 202592 flights65.9%
Oct–Dec 202591 flights76.4%
Jan–Mar 202690 flights83.5%
Apr–Jun 202691 flights80.9%

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 76.6% on time across 364 flights.

Delta on SEA to MCI did not run the same all year. Its best quarter was Jan–Mar 2026 at 83.5% on time and its weakest Jul–Sep 2025 at 65.9%, a swing of 18 points on roughly 91 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Saturday is the strongest day at 82.4% on time and Sunday the weakest at 71.4%. 11 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 58% of the 5,655 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.

Carrier
58%
Late-arriving aircraft
26%
National Airspace System
12%
Extreme weather
4%

The largest share of delay minutes, 58%, 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 3,283 of the 5,655 delay minutes reported here. The split is drawn from 5,655 reported delay minutes.

Cancellations sit at 1.65% against a national 1.81%, which is ordinary. Diversions add another 1.10%.

Connections and stage length

What a delay here costs

8.8% of arrivals land an hour or more late, close to the national 8.1%. 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 last a little over an hour, which a normal layover absorbs.

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 85.3% on time across 364 flights, 9 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 9 points of difference.

One caution: this is a thin sample. 364 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 Delta on SEA to MCI

Put together: treat all of this as provisional. 364 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 76.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 354 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