Carrier route record

ASSEA→IAH

Alaska Airlines · Seattle to Houston

Flights: 852
Period: July 2025 to June 2026
Share of route: 41%
Carriers: 2

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

Alaska on SEA to IAH 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 77.6%. The late ones land about 45 minutes behind schedule. That rests on 852 flights, with a median arrival 2 minutes early.

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

On time

74.3%

Arrivals under 15 minutes late, of 844 completed flights

Avg delay

45 min

Across delayed arrivals only, not all flights

Cancelled

0.70%

National rate is 1.81%

Whole route

80.3%

Every carrier on SEA to IAH, 2,095 flights

These figures cover 852 flights between July 2025 and June 2026. The median arrival is 2 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 SEA to IAH

Alaska flew 852 of the 2,095 flights on SEA to IAH, about 41% of it. Its 74.3% on time is 6 points worse than the route as a whole, which runs 80.3%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from United at 84.5% to Alaska at 74.3%.

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 IAH
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	1,243	84.5%	70 min	0.56%	B+
Alaska Airlines (this page)	852	74.3%	45 min	0.70%	C+

Flight by flight

Alaska flight numbers on SEA to IAH

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–8am—
8am–11am118 flights81.9%
11am–2pm247 flights59.2%
2pm–5pm—
5pm–8pm279 flights83.4%
8pm–5am208 flights75.7%

Scale runs 50% to 90%. 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 59.2% on time against 83.4% for 5pm–8pm. 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 5pm–8pm window is the busiest, with 279 flights scheduled in it.

Across the year

Alaska on SEA to IAH through the year

Darker means more delays. Figures are on-time percentages.February best, July worst

July is the worst month at 54.4% on time, 35 points below February, the best at 89.3%. 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. July was the busiest month here, with 92 flights.

Across the week, Saturday is the strongest day at 78.9% on time and Friday the weakest at 66.4%. 13 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Alaska runs late on this route

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 9,679 reported delay minutes.

Carrier
38%
National Airspace System
31%
Late-arriving aircraft
29%
Extreme weather
1%
Security
1%

The largest share of delay minutes, 38%, 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 3,684 of the 9,679 delay minutes reported here. The split is drawn from 9,679 reported delay minutes.

Cancellations are rare at 0.70%, 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 4.4% 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.

At 1,874 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 78.5% on time across 852 flights, 4 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 4 points of difference.

One caution: this is a thin sample. 852 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 SEA to IAH

Put together: treat all of this as provisional. 852 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 74.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 844 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