Carrier route record

ASSEA→ATL

Alaska Airlines · Seattle to Atlanta

Flights: 905
Period: July 2025 to June 2026
Share of route: 28%
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 ATL lands a B+, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That is a workable record, not a spotless one. That rests on 905 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 Alaska on SEA to ATL from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

80.3%

Arrivals under 15 minutes late, of 894 completed flights

Avg delay

46 min

Across delayed arrivals only, not all flights

Cancelled

0.66%

National rate is 1.81%

Whole route

82.8%

Every carrier on SEA to ATL, 3,276 flights

These figures cover 905 flights between July 2025 and June 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.

Carrier by carrier

Alaska against every carrier on SEA to ATL

Alaska flew 905 of the 3,276 flights on SEA to ATL, about 28% of it. Its 80.3% on time is 3 points worse than the route as a whole, which runs 82.8%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from Delta at 83.8% to Alaska at 80.3%.

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 ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	2,371	83.8%	86 min	0.51%	B+
Alaska Airlines (this page)	905	80.3%	46 min	0.66%	B+

Flight by flight

Alaska flight numbers on SEA to ATL

AS 33409:2884.9% · 315 flights

Departure window

When Alaska 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 905 flights.

5am–8am—
8am–11am365 flights82.8%
11am–2pm—
2pm–5pm236 flights73.1%
5pm–8pm—
8pm–5am304 flights82.9%

Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.

The overnight block holds up unusually well at 82.9% on time across 304 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8am–11am window is the busiest, with 365 flights scheduled in it.

Across the year

Alaska on SEA to ATL through the year

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

July is the worst month at 48.4% on time, 52 points below February, the best at 100.0%. 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, Wednesday is the strongest day at 87.1% on time and Saturday the weakest at 73.2%. 14 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 8,137 reported delay minutes.

Carrier
41%
Late-arriving aircraft
37%
National Airspace System
22%
Extreme weather
1%

37% 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 8,137 reported delay minutes here, that single category outweighs weather by 37 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 8,137 reported delay minutes.

The largest share of delay minutes, 41%, 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 3,326 of the 8,137 delay minutes reported here.

Cancellations are rare at 0.66%, 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 3.7% 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.

At 2,182 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 74.3% on time across 906 flights, 6 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 6 points of difference.

One caution: this is a thin sample. 905 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 ATL

Put together: treat all of this as provisional. 905 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 80.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 894 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