Carrier route record

ASBWI→SEA

Alaska Airlines · Baltimore to Seattle

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 BWI to SEA sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.6%. The late ones land roughly 50 minutes behind schedule. That rests on 599 flights, with a median arrival right on schedule.

The national on-time rate over the same period is 77.6%, so Alaska on BWI to SEA runs 9 points behind the country as a whole. Across a thousand flights that is about 88 extra late arrivals.

On time

68.8%

Arrivals under 15 minutes late, of 593 completed flights

Avg delay

48 min

Across delayed arrivals only, not all flights

Cancelled

0.83%

National rate is 1.81%

Whole route

68.4%

Every carrier on BWI to SEA, 719 flights

These figures cover 599 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.

Carrier by carrier

Alaska against every carrier on BWI to SEA

Alaska flew 599 of the 719 flights on BWI to SEA, most of the route. Its 68.8% on time is about level with the route as a whole at 68.4%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Alaska at 68.8% to Southwest at 66.7%. 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 BWI to SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlines (this page)	599	68.8%	48 min	0.83%	C+
Southwest Airlinesthin sample	120	66.7%	74 min	0.00%	C+

Flight by flight

Alaska flight numbers on BWI to SEA

AS 37919:1063.1% · 336 flights

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 20 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–8am187 flights73.8%
8am–11am72 flights82.9%
11am–2pm—
2pm–5pm—
5pm–8pm340 flights63.1%
8pm–5am—

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

The 5pm–8pm window is where this operation falls apart: 63.1% on time, against 82.9% for the 8am–11am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5pm–8pm window is the busiest, with 340 flights scheduled in it.

Across the year

Alaska on BWI to SEA through the year

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

December is the weak month at 32.2% on time, against 88.9% in October. 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. August was the busiest month here, with 62 flights.

Across the week, Sunday is the strongest day at 75.6% on time and Thursday the weakest at 63.6%. 12 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 8,852 reported delay minutes.

National Airspace System
36%
Late-arriving aircraft
33%
Carrier
17%
Extreme weather
10%
Security
3%

36% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 3,209 minutes out of 8,852, against a national NAS share of 21%. The split is drawn from 8,852 reported delay minutes.

The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 82.9% on time here.

Cancellations are rare at 0.83%, 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

6.4% 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 roughly 50 minutes, which a normal layover absorbs.

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 82.8% on time across 599 flights, 14 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 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 BWI to SEA

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 68.8% 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