Flight profile · Alaska Airlines
AS390
San Diego (SAN) to Boston (BOS) · scheduled 8:40 AM – 6:59 PM
How AS390 performs
1,074 operations, July 2023 – July 2026.
Source: US DOT Bureau of Transportation Statistics · 1,074 operations, July 2023 – July 2026 · If AS390 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where AS390 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
Ask for the position of AS390 right now, if receivers on the ground are hearing it. Nothing is requested until you press the button.
Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| AS390 | 74.9% | 0.56% | -3 min | 10.2% | 1,074 |
| Alaska Airlines on SAN → BOS | 76.2% | 0.72% | -3 min | 8.8% | 1,391 |
| All SAN → BOS flights | 75.5% | 0.86% | -6 min | 8.8% | 5,087 |
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026
Why AS390 runs late
Where US DOT attributed the delay minutes on this flight.
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
weather severe enough to stop this flight specifically
crew, maintenance, boarding and fueling, all within the carrier’s control
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for AS390 on SAN → BOS. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies AS390 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, AS390 pushed back an average of 25 minutes late; when it came in on time or early, an average of 8 minutes late.
Each departure is matched to the flight the same aircraft flew into SAN just before it, using the tail number in the DOT file, 826 of 1,069 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| AS390 | 24% | 46% | 17% |
| Network, same turn | 23% | 40% | 9% |
The schedule leaves a long gap on the ground, which gives a late aircraft room to catch up before this flight pushes back.
The network row is every flight with a scheduled turn of 90 minutes to 3 hours. How often AS390’s aircraft landed 15 or more minutes late is about the same as the network’s and, once the aircraft was late, how often AS390 left 15 or more minutes late is higher than the network’s.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
From pushback to gate
When it leaves SAN late, does that still matter by the time it reaches BOS?
AS390 pushes back an average of 14.8 minutes late and reaches the gate at BOS an average of 7.4 minutes late. The 7.4 minutes between those two figures are slack the published schedule already carries, which is why a late pushback on this flight does not reliably become a late arrival. It spends 26.8 minutes on the taxiways at SAN, 3.7 minutes longer than a typical SAN departure in the same hour.
On arrival at BOS, AS390 spends 11.5 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 2.5 minutes longer than a typical BOS arrival (9.0 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached BOS. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 23,995 departures from SAN scheduled in the clock hour AS390 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at BOS (440,886 flights), not just AS390’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026
The hour it leaves SAN
Part of any flight’s record belongs to the clock rather than to the flight. AS390 has one departure time, so this is what that time is worth.
On-time arrival rate. 23,995 departures from SAN are scheduled in the 8 AM–9 AM hour over the period, against 297,668 across the whole day.
AS390 is scheduled out of SAN at 8:40 AM, in the 8 AM–9 AM bank. Departures from SAN in that hour arrive on time 81.7% of the time against 77.9% across the airport’s whole day — the slot alone is worth 3.8 points better before anything about this particular flight is considered.
The two airport figures cover every departure from SAN to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Hours below 120 departures are not scored.
By day of week
Does AS390 run worse on particular days?
Saturday is historically the most reliable day and Sunday the least, a gap of 14.4 percentage points.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Days with fewer than 120 operations are not scored.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
60 min late
against a median of 3 min early
AS390 has an average that understates its risk: a typical arrival is 3 min early, but the worst tenth are 63 minutes worse than that. If the trip has something unmissable at the end of it, the median is the wrong number to plan against.
Percentiles over 1,074 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| B62120 | JetBlue | 78.8% | 10 min early | 1,052 |
| AS390 this flight | Alaska Airlines | 74.9% | 3 min early | 1,074 |
| B6620 | JetBlue | 69.7% | 4 min early | 848 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. AS390 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 1,074 records of AS390 operating SAN → BOS, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
Analysis last recomputed