Flight number record

AS 377

Alaska Airlines · Atlanta to Seattle

Route: ATL → SEA
Departs: 07:00
Flights: 315
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s AS 377, check with Alaska Airlines.

AS 377 earns an A+. 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 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 315 flights, with a median arrival 9 minutes early.

Set against the rest of the country, AS 377's record is 7 points better than the US average of 77.6%. That gap is worth roughly 74 fewer late arrivals for every thousand flights.

On time

85.0%

Arrivals under 15 minutes late, of 314 completed flights

Avg delay

75 min

Across delayed arrivals only, not all flights

Cancelled

0.32%

National rate is 1.81%

1 hour+ late

4.5%

National rate is 8.1%

These figures cover 315 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 377 flies

AS 377 flies ATL to SEA without a single fixed slot. Its most common scheduled departure was 07:00, used on 128 of 315 flights, with 06:30 (50 flights) and 07:20 (36 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 07:00128 flights40.6%
Departs 06:3050 flights15.9%
Departs 07:2036 flights11.4%

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 07:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and AS 377 runs 4 points worse at 85.0%. 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 377 next to ATL to SEA

Every carrier on ATL to SEA combined arrived on time 77.8% of the time across 3,277 flights, so AS 377 is 7 points ahead of it. Alaska flew 906 flights on the same city pair under all its flight numbers, including this one, and those ran 74.3% on time. Across its whole network Alaska Airlines managed 79.1%, which this flight beats by 6 points.

AS 377 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
AS 377thin sample	315	85.0%	75 min	0.32%	A+
All Alaska Airlines on ATL–SEA	906	74.3%	55 min	1.10%	C
All carriers on ATL–SEA	3,277	77.8%	54 min	0.64%	B+
Alaska Airlines, whole network	293,372	79.1%	52 min	1.28%	B

Across the year

AS 377 quarter by quarter

AS 377 did not run the same all year. Its best quarter was Jul–Sep 2025 at 92.5% on time and its weakest Jan–Mar 2026 at 74.4%, a swing of 18 points on roughly 79 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 202580 flights92.5%
Oct–Dec 202554 flights81.5%
Jan–Mar 202690 flights74.4%
Apr–Jun 202691 flights91.1%

Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, AS 377 did best on Wednesday at 94.3% on time and worst on Sunday at 80.4%. Each day rests on about 45 flights, so a gap of 14 points is worth noticing but could still narrow in another year.

Delay causes

Why AS 377 runs late

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 3,546 reported delay minutes.

Carrier
35%
Late-arriving aircraft
34%
National Airspace System
21%
Extreme weather
10%
Security
1%

The largest share of delay minutes, 35%, 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 1,244 of the 3,546 delay minutes reported here. The split is drawn from 3,546 delay minutes reported on AS 377.

Cancellations are rare at 0.32%, 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 4.5% 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 2,182 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 MSO to SEA (26), but none flew often enough under AS 377 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ATL to SEA only.

One caution: this is a thin sample. 315 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 377

For a booking, AS 377 has one of the better records a US domestic flight can show: 85.0% on time and 0.32% cancelled. That is a base rate, not a promise about any single 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