Route profile
SEA→BWI
Flight reliability, delays and best times to fly from Seattle to Baltimore, 2,335 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 84% of comparable major US routes (4,598 compared)
Calculated from 1,945 flights. How this is calculated
SEA → BWI arrives on time 78.7% of the time; the return trip, BWI → SEA, arrives on time 68.5% of the time, a 10.2-point gap between the two directions of the same city pair.
SEA → BWI spends 29.1 minutes on the ground on a 2,335-mile trip: 23.4 minutes from pushback to wheels-up at SEA and 5.8 minutes from touchdown to gate at BWI.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What sets this route apart
Where SEA to BWI differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
In May, SEA to BWI runs 6.6 points below routes of similar length, 71.2% on time to 77.8%.
Alaska Airlines does better on SEA to BWI than on its routes of similar length: 80.1% on time here, 76.1% there, 4 points apart. Against all other routes the gap is 2.1 points.
SEA to BWI against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Month: May | 71.2% | routes of similar length | 77.8% | −6.6 pts | 177 here, 95,279 there |
| Airline: Alaska Airlines | 80.1% | routes of similar length | 76.1% | +4.0 pts | 1,738 here, 164,586 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 2,335 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
When it goes wrong
July 2023 – July 2026
29 min late
against a median of 3 min early
Percentiles over 1,945 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at BWI after arriving from SEA.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 43% | Likely to miss |
| 45 min | 20% | High risk |
| 60 min | 9.6% | Some risk |
| 90 min | 3.3% | Low risk |
| 120 min | 1.3% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.62% of the time and diverts 0.46% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,924 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 29 minutes late (90th-percentile gate arrival delay), over 1,945 operations.
Any other layover length: connection checker.
Why SEA → BWI runs late
July 2023 – July 2026
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for SEA → BWI. Only delays of 15 minutes or more are attributed.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Alaska Airlines | 1,759 | 80.1% | 0.68% | -4 min | 3.1% |
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
| Flight | Scheduled | Operations | On time |
|---|---|---|---|
| AS378 Alaska Airlines | 9:55 AM | 958 | 78.4% |
Weekly and seasonal patterns
By day of week
Tuesday is historically the most reliable day and Sunday the least, a gap of 11.0 percentage points.
By month
- Jan to Mar: no data
- Apr: 81.7%
- May: 71.2%
- Jun: 79.3%
- Jul: 72.6%
- Aug: 75.0%
- Sep: 81.7%
- Oct: 86.2%
- Nov: 87.7%
- Dec: 83.4%
May is historically the weakest month and November the strongest, a spread of 16.5 percentage points.
Reliability over time
July 2023 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 80.2% against 76.6% in the 12 months before — improving by 3.6 percentage points.
Data and methodology
Calculated by FlyerIntel from 1,945 SEA → BWI flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed