Carrier route record

ASSEA→BWI

Alaska Airlines · Seattle to Baltimore

Flights: 599
Period: July 2025 to June 2026
Share of route: 83%
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 BWI 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 roughly 45 minutes on average. That is a workable record, not a spotless one. That rests on 599 flights, with a median arrival 9 minutes early.

Set against the rest of the country, Alaska's SEA to BWI record is 5 points better than the US average of 77.6%. That gap is worth roughly 52 fewer late arrivals for every thousand flights.

On time

82.8%

Arrivals under 15 minutes late, of 593 completed flights

Avg delay

43 min

Across delayed arrivals only, not all flights

Cancelled

0.50%

National rate is 1.81%

Whole route

80.4%

Every carrier on SEA to BWI, 719 flights

These figures cover 599 flights between July 2025 and June 2026. The median arrival is 9 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 BWI

Alaska flew 599 of the 719 flights on SEA to BWI, most of the route. Its 82.8% on time is 2 points better than the route as a whole, which runs 80.4%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Alaska at 82.8% to Southwest at 68.3%. 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 BWI
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlines (this page)	599	82.8%	43 min	0.50%	B+
Southwest Airlinesthin sample	120	68.3%	41 min	0.00%	C+

Flight by flight

Alaska flight numbers on SEA to BWI

AS 37810:1182.2% · 337 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 599 flights.

5am–8am—
8am–11am365 flights82.5%
11am–2pm—
2pm–5pm—
5pm–8pm—
8pm–5am234 flights83.3%

Scale runs 75% to 90%. Rows with fewer than 30 flights show a dash.

The overnight block holds up unusually well at 83.3% on time across 234 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 BWI through the year

Darker means more delays. Figures are on-time percentages.April best, August worst

August is the worst month at 69.4% on time, 25 points below April, the best at 94.7%. 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. August was the busiest month here, with 62 flights.

Across the week, Saturday is the strongest day at 89.6% on time and Thursday the weakest at 78.2%. 11 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. Carrier accounts for 53% of the 4,360 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
53%
Late-arriving aircraft
21%
National Airspace System
21%
Extreme weather
5%

The largest share of delay minutes, 53%, 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 2,321 of the 4,360 delay minutes reported here. The split is drawn from 4,360 reported delay minutes.

Cancellations are rare at 0.50%, 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 2.9% 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 2,335 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 68.8% on time across 599 flights, 14 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 14 points of difference.

One caution: this is a thin sample. 599 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 BWI

Put together: treat all of this as provisional. 599 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 82.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 593 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