Flight number record

AS 390

Alaska Airlines · San Diego to Boston

Route: SAN → BOS
Departs: 08:50
Flights: 358
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s AS 390, check with Alaska Airlines.

AS 390 sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 358 flights, with a median arrival 2 minutes early.

On time

74.3%

Arrivals under 15 minutes late, of 346 completed flights

Avg delay

73 min

Across delayed arrivals only, not all flights

Cancelled

1.40%

National rate is 1.81%

1 hour+ late

9.5%

National rate is 8.1%

These figures cover 358 flights between July 2025 and June 2026. Beyond the headline rate, 9.5% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Schedule

When AS 390 flies

AS 390 flies SAN to BOS without a single fixed slot. Its most common scheduled departure was 08:50, used on 79 of 358 flights, with 08:40 (50 flights) and 07:00 (49 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 08:5079 flights22.1%
Departs 08:4050 flights14.0%
Departs 07:0049 flights13.7%

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 08:50 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and AS 390 runs 10 points worse at 74.3%. 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 390 next to SAN to BOS

Every carrier on SAN to BOS combined arrived on time 77.9% of the time across 1,818 flights, so AS 390 is 4 points behind it. Across its whole network Alaska Airlines managed 79.1%, which this flight trails by 5 points.

AS 390 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
AS 390thin sample	358	74.3%	73 min	1.40%	C
All Alaska Airlines on SAN–BOS	508	76.2%	66 min	1.77%	B
All carriers on SAN–BOS	1,818	77.9%	85 min	1.54%	B
Alaska Airlines, whole network	293,372	79.1%	52 min	1.28%	B

Across the year

AS 390 quarter by quarter

AS 390 did not run the same all year. Its best quarter was Apr–Jun 2026 at 91.1% on time and its weakest Jul–Sep 2025 at 62.2%, a swing of 29 points on roughly 90 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 flights62.2%
Oct–Dec 202590 flights65.5%
Jan–Mar 202685 flights78.5%
Apr–Jun 202691 flights91.1%

Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, AS 390 did best on Saturday at 95.6% on time and worst on Sunday at 66.0%. Each day rests on about 51 flights, so a gap of 30 points is worth noticing but could still narrow in another year.

Delay causes

Why AS 390 runs late

One category carries most of the weight here. National Airspace System accounts for 56% of the 6,481 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.

National Airspace System
56%
Extreme weather
21%
Late-arriving aircraft
21%
Carrier
3%

Extreme weather accounts for 21% 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 quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.3 times the usual weather exposure. The split is drawn from 6,481 delay minutes reported on AS 390.

Cancellations sit at 1.40% against a national 1.81%, which is ordinary. Diversions add another 1.96%.

Connections and routes

What a delay on this flight costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.5% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

At 2,588 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.

Every one of the 358 flights under AS 390 in the data flew SAN to BOS. The number was not reused on any other city pair, which makes this a clean record of one route.

One caution: this is a thin sample. 358 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 390

For a booking, read AS 390 as 74.3% on time with 1.40% cancelled over 358 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