Flight number record
AS 306
Alaska Airlines · Seattle to Boston
- Route
- SEA → BOS
- Departs
- 08:23
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s AS 306, check with Alaska Airlines.
AS 306 sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 365 flights, with a median arrival 2 minutes early.
Key figures
On time
75.6%
Arrivals under 15 minutes late, of 360 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
1.37%
National rate is 1.89%
1 hour+ late
7.5%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 2026. The median arrival is 2 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 306 flies
AS 306 flies SEA to BOS without a single fixed slot. Its most common scheduled departure was 08:23, used on 70 of 365 flights, with 09:00 (42 flights) next.
- Departs 08:2370 flights19.2%
- Departs 09:0042 flights11.5%
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 08:23 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and AS 306 runs 8 points worse at 75.6%. 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 306 next to SEA to BOS
Every carrier on SEA to BOS combined arrived on time 75.1% of the time across 2,554 flights, so AS 306 is about level with it. Alaska flew 1,240 flights on the same city pair under all its flight numbers, including this one, and those ran 77.5% on time. Across its whole network Alaska Airlines managed 79.7%, which this flight trails by 4 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| AS 306 | 365 | 75.6% | 59 min | 1.37% | B |
| All Alaska Airlines on SEA–BOS | 1,240 | 77.5% | 51 min | 1.13% | B |
| All carriers on SEA–BOS | 2,554 | 75.1% | 64 min | 1.49% | B |
| Alaska Airlines, whole network | 309,844 | 79.7% | 52 min | 1.20% | B |
Across the year
AS 306 quarter by quarter
AS 306 did not run the same all year. Its best quarter was Jan–Mar 2026 at 91.9% on time and its weakest Jul–Sep 2025 at 66.7%, a swing of 25 points on roughly 73 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 flights66.7%
- Oct–Dec 202592 flights73.6%
- Jan–Mar 202690 flights91.9%
- Apr–Jun 202691 flights70.3%
- Jul–Sep 202662 flights67.7%
Scale runs 60% to 95%.
By weekday, AS 306 ranged from 71.2% on Tuesday to 82.4% on Sunday. With about 52 flights behind each day, a spread of 11 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late AS 306 runs when it is late
AS 306 often beats the schedule: 107 of 360 completed flights, 30%, arrived 15 minutes or more early. The 88 late arrivals split 38 under half an hour, 23 between 30 and 60 minutes, and 27 an hour or more.
- 15+ min early107 flights29.7%
- Within 15 min165 flights45.8%
- 15–29 min late38 flights10.6%
- 30–59 min late23 flights6.4%
- 1–2 hours late18 flights5.0%
- 2+ hours late9 flights2.5%
Scale runs 0% to 100%.
Share of 360 completed flights by arrival against schedule.
A late pushback is often recovered here: of 87 departures that left 15 minutes late or more, 32 still arrived on time. In the other direction, 33 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at BOS.
The worst days
Worst days for AS 306
The latest arrival of the period was on 13 March 2026, 6 hours 37 minutes behind schedule; most of its delay minutes were filed as extreme weather. On three of the five worst days the largest share was filed as national airspace system delay.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 March 2026 | 6 hours 37 minutes | Extreme weather |
| 13 October 2025 | 4 hours 46 minutes | National Airspace System |
| 29 April 2026 | 3 hours 31 minutes | Late-arriving aircraft |
| 10 November 2025 | 3 hours 30 minutes | National Airspace System |
| 25 September 2025 | 3 hours 18 minutes | National Airspace System |
Delay causes
Why AS 306 runs late
National Airspace System accounts for 60% of the 5,206 delay minutes carriers reported here, and the remaining four split what is left.
- 60%National Airspace System
- 19%Carrier
- 13%Extreme weather
- 8%Late-arriving aircraft
Extreme weather accounts for 13% 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 2.2 times the usual weather exposure. The split is drawn from 5,206 delay minutes reported on AS 306.
Cancellations sit at 1.37% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
7.5% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
At 2,496 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 BOS to SEA (129), but none flew often enough under AS 306 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SEA to BOS only.
One caution: this is a thin sample. 365 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 306
For a booking, read AS 306 as 75.6% on time with 1.37% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SEA to BOS, every carrier and departure
- BOS to SEA, the return direction
- Delta Air Lines 459 on the same route88.1%
- Delta Air Lines 473 on the same route83.5%
- Alaska Airlines 460 on the same route81.8%
- Seattle-Tacoma International (SEA) delay statistics
- Boston Logan International (BOS) 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.