Flight number record

AS 378

Alaska Airlines · Seattle to Baltimore

Route: SEA → BWI
Departs: 10:11
Flights: 337
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s AS 378, check with Alaska Airlines.

AS 378 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 about 45 minutes on average. That is a workable record, not a spotless one. That rests on 337 flights, with a median arrival 9 minutes early.

Set against the rest of the country, AS 378's record is 5 points better than the US average of 77.6%. That gap is worth roughly 46 fewer late arrivals for every thousand flights.

On time

82.2%

Arrivals under 15 minutes late, of 332 completed flights

Avg delay

45 min

Across delayed arrivals only, not all flights

Cancelled

0.59%

National rate is 1.81%

1 hour+ late

3.3%

National rate is 8.1%

These figures cover 337 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.

Schedule

When AS 378 flies

AS 378 flies SEA to BWI without a single fixed slot. Its most common scheduled departure was 10:11, used on 62 of 337 flights, with 10:03 (50 flights) and 10:10 (45 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 10:1162 flights18.4%
Departs 10:0350 flights14.8%
Departs 10:1045 flights13.4%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 10:11 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and AS 378 runs level with that at 82.2%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

AS 378 next to SEA to BWI

Every carrier on SEA to BWI combined arrived on time 80.4% of the time across 719 flights, so AS 378 is 2 points ahead of it. Alaska flew 599 flights on the same city pair under all its flight numbers, including this one, and those ran 82.8% on time. Across its whole network Alaska Airlines managed 79.1%, which this flight beats by 3 points.

AS 378 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
AS 378thin sample	337	82.2%	45 min	0.59%	B+
All Alaska Airlines on SEA–BWI	599	82.8%	43 min	0.50%	B+
All carriers on SEA–BWI	719	80.4%	42 min	0.42%	B+
Alaska Airlines, whole network	293,372	79.1%	52 min	1.28%	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 67.8%, a swing of 23 points on roughly 84 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 202592 flights67.8%
Oct–Dec 202592 flights87.0%
Jan–Mar 202690 flights86.2%
Apr–Jun 202663 flights90.5%

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, AS 378 did best on Saturday at 89.6% on time and worst on Monday at 76.1%. Each day rests on about 48 flights, so a gap of 14 points is worth noticing but could still narrow in another year.

Delay causes

Why AS 378 runs late

One category carries most of the weight here. Carrier accounts for 56% of the 2,666 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
56%
National Airspace System
23%
Late-arriving aircraft
12%
Extreme weather
8%

The largest share of delay minutes, 56%, 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 1,497 of the 2,666 delay minutes reported here. The split is drawn from 2,666 delay minutes reported on AS 378.

Cancellations are rare at 0.59%, 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 routes

What a delay on this flight costs

Badly late arrivals are rare here: only 3.3% 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 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 82.2% on time with 0.59% cancelled over 337 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures