Carrier route record
ASBWI→SEA
Alaska Airlines · Baltimore to Seattle
- Flights
- 599
- Period
- September 2025 to August 2026
- Share of route
- 83%
- Carriers
- 2
Historical statistics for September 2025 to August 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 77.3%. The late ones land roughly 50 minutes behind schedule. That rests on 599 flights, with a median arrival 1 minute late.
The national on-time rate over the same period is 77.3%, so Alaska on BWI to SEA runs 9 points behind the country as a whole. Across a thousand flights that is about 91 extra late arrivals.
Key figures
On time
68.2%
Arrivals under 15 minutes late, of 594 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
0.83%
National rate is 1.89%
Whole route
66.8%
Every carrier on BWI to SEA, 719 flights
These figures cover 599 flights between September 2025 and August 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.
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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 68.2% on time is about level with the route as a whole at 66.8%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Alaska at 68.2% to Southwest at 59.7%. 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlines (this page) | 599 | 68.2% | 49 min | 0.83% | C+ |
| Southwest Airlinesthin sample | 120 | 59.7% | 64 min | 0.83% | D+ |
Flight by flight
Alaska flight numbers on BWI to SEA
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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.
- 5am–8am207 flights74.8%
- 8am–11am52 flights82.4%
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm340 flights62.0%
- 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: 62.0% on time, against 82.4% 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
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, Monday is the strongest day at 73.3% on time and Thursday the weakest at 61.4%, a spread of 12 points.
Arrival by arrival
How late Alaska on BWI to SEA runs when it is late
The 189 late arrivals split 75 under half an hour, 71 between 30 and 60 minutes, and 43 an hour or more.
- 15+ min early131 flights22.1%
- Within 15 min274 flights46.1%
- 15–29 min late75 flights12.6%
- 30–59 min late71 flights12.0%
- 1–2 hours late30 flights5.1%
- 2+ hours late13 flights2.2%
Scale runs 0% to 100%.
Share of 594 completed flights by arrival against schedule.
33 of 144 late departures made up the time and arrived on time, 23% of them. In the other direction, 78 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SEA.
The worst days
Worst days for Alaska on BWI to SEA
The latest arrival of the period was on 11 June 2026, 4 hours 56 minutes behind schedule; most of its delay minutes were filed as extreme weather. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 11 June 2026 | 4 hours 56 minutes | Extreme weather |
| 13 March 2026 | 4 hours 18 minutes | Late-arriving aircraft |
| 18 July 2026 | 3 hours 7 minutes | Extreme weather |
| 14 June 2026 | 3 hours 5 minutes | Extreme weather |
| 3 December 2025 | 2 hours 49 minutes | Carrier |
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 9,167 reported delay minutes.
- 40%National Airspace System
- 29%Late-arriving aircraft
- 15%Extreme weather
- 13%Carrier
- 3%Security
Extreme weather accounts for 15% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.5 times the usual weather exposure. The split is drawn from 9,167 reported delay minutes.
40% 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 3,649 minutes out of 9,167, against a national NAS share of 21%.
Cancellations are rare at 0.83%, below the national 1.89% 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
7.2% of arrivals land an hour or more late, close to the national 8.3%, so 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 84.8% on time across 599 flights, 17 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 17 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 68.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 594 completed flights over 12 months sit behind that.
Related
Where to go next
- BWI to SEA, every carrier
- Alaska on SEA to BWI, the return leg
- Southwest Airlines on BWI to SEA59.7%
- Alaska Airlines network-wide record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.