Flight number record
AS 378
Alaska Airlines · Seattle to Baltimore
- Route
- SEA → BWI
- Departs
- 09:03
- Flights
- 337
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s AS 378, check with Alaska Airlines.
AS 378 earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.3%. When something does go wrong the average delay runs about 45 minutes. That rests on 337 flights, with a median arrival 9 minutes early.
Set against the rest of the country, AS 378's record is 7 points better than the US average of 77.3%. That gap is worth roughly 67 fewer late arrivals for every thousand flights.
Key figures
On time
84.0%
Arrivals under 15 minutes late, of 331 completed flights
Avg delay
46 min
Across delayed arrivals only, not all flights
Cancelled
0.59%
National rate is 1.89%
1 hour+ late
2.7%
National rate is 8.3%
These figures cover 337 flights between September 2025 and August 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.
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Schedule
When AS 378 flies
AS 378 flies SEA to BWI without a single fixed slot. Its most common scheduled departure was 09:03, used on 92 of 337 flights, with 10:11 (62 flights) and 09:46 (34 flights) next.
- Departs 09:0392 flights27.3%
- Departs 10:1162 flights18.4%
- Departs 09:4634 flights10.1%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 09:03 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and AS 378 runs level with that at 84.0%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
AS 378 next to SEA to BWI
Every carrier on SEA to BWI combined arrived on time 80.7% of the time across 719 flights, so AS 378 is 3 points ahead of it. Alaska flew 599 flights on the same city pair under all its flight numbers, including this one, and those ran 84.8% on time. Across its whole network Alaska Airlines managed 79.7%, which this flight beats by 4 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| AS 378thin sample | 337 | 84.0% | 46 min | 0.59% | B+ |
| All Alaska Airlines on SEA–BWI | 599 | 84.8% | 39 min | 0.67% | B+ |
| All carriers on SEA–BWI | 719 | 80.7% | 40 min | 0.70% | B+ |
| Alaska Airlines, whole network | 309,844 | 79.7% | 52 min | 1.20% | B |
Across the year
AS 378 quarter by quarter
AS 378 did not run the same all year. Its best quarter was Apr–Jun 2026 at 90.5% on time and its weakest Jul–Sep 2025 at 73.3%, a swing of 17 points on roughly 67 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights73.3%
- Oct–Dec 202592 flights87.0%
- Jan–Mar 202690 flights86.2%
- Apr–Jun 202663 flights90.5%
- Jul–Sep 202662 flights74.6%
Scale runs 65% to 95%.
By weekday, AS 378 did best on Saturday at 91.5% on time and worst on Thursday at 74.5%. Each day rests on about 48 flights, so a gap of 17 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late AS 378 runs when it is late
AS 378 often beats the schedule: 128 of 331 completed flights, 39%, arrived 15 minutes or more early. Most of the lateness is short. 27 of the 53 late arrivals were under half an hour behind, and 9 reached an hour or more.
- 15+ min early128 flights38.7%
- Within 15 min150 flights45.3%
- 15–29 min late27 flights8.2%
- 30–59 min late17 flights5.1%
- 1–2 hours late4 flights1.2%
- 2+ hours late5 flights1.5%
Scale runs 0% to 100%.
Share of 331 completed flights by arrival against schedule.
A late pushback is often recovered here: of 69 departures that left 15 minutes late or more, 29 still arrived on time. 13 flights left on time and still arrived late.
The worst days
Worst days for AS 378
The latest arrival of the period was on 13 March 2026, 3 hours 40 minutes behind schedule; most of its delay minutes were filed as extreme weather. On four of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 March 2026 | 3 hours 40 minutes | Extreme weather |
| 12 November 2025 | 3 hours 24 minutes | Carrier |
| 8 January 2026 | 3 hours 2 minutes | Carrier |
| 2 April 2026 | 2 hours 22 minutes | Carrier |
| 9 September 2025 | 2 hours 1 minute | Carrier |
Delay causes
Why AS 378 runs late
Carrier accounts for 56% of the 2,421 delay minutes carriers reported here, and the remaining four split what is left.
- 56%Carrier
- 20%National Airspace System
- 16%Late-arriving aircraft
- 9%Extreme weather
The largest share of delay minutes, 56%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,359 of the 2,421 delay minutes reported here. The split is drawn from 2,421 delay minutes reported on AS 378.
Cancellations are rare at 0.59%, 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 routes
What a delay on this flight costs
Badly late arrivals are rare here: only 2.7% land an hour or more behind schedule, against 8.3% 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 same number turns up on one other city pair in the data, including SEA to ANC (28), but none flew often enough under AS 378 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SEA to BWI only.
One caution: this is a thin sample. 337 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 AS 378
For a booking, read AS 378 as 84.0% on time with 0.59% cancelled over 337 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SEA to BWI, every carrier and departure
- BWI to SEA, the return direction
- Seattle-Tacoma International (SEA) delay statistics
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Alaska Airlines on-time record
- Every Alaska Airlines flight number with a record
- The most and least reliable flight numbers in the US
- Worst months to fly in the US, ranked by the data
A flight number here means Alaska Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.