Flight number record
AS 637
Alaska Airlines · Phoenix to Seattle
- Route
- PHX → SEA
- Departs
- 09:10
- Flights
- 364
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s AS 637, check with Alaska Airlines.
AS 637 earns a B+. 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 77.3%. When something does go wrong the average delay runs about an hour. That rests on 364 flights, with a median arrival 6 minutes early.
Set against the rest of the country, AS 637's record is 7 points better than the US average of 77.3%. That gap is worth roughly 67 fewer late arrivals for every thousand flights.
Key figures
On time
84.0%
Arrivals under 15 minutes late, of 362 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
0.27%
National rate is 1.89%
1 hour+ late
4.4%
National rate is 8.3%
These figures cover 364 flights between September 2025 and August 2026. The median arrival is 6 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 637 flies
AS 637 flies PHX to SEA without a single fixed slot. Its most common scheduled departure was 09:10, used on 70 of 364 flights, with 09:00 (50 flights) next.
- Departs 09:1070 flights19.2%
- Departs 09:0050 flights13.7%
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 09:10 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and AS 637 runs level with that at 84.0%. 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 637 next to PHX to SEA
Every carrier on PHX to SEA combined arrived on time 82.2% of the time across 7,202 flights, so AS 637 is 2 points ahead of it. Alaska flew 2,886 flights on the same city pair under all its flight numbers, including this one, and those ran 84.4% on time. Across its whole network Alaska Airlines managed 79.7%, which this flight beats by 4 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| AS 637thin sample | 364 | 84.0% | 59 min | 0.27% | B+ |
| All Alaska Airlines on PHX–SEA | 2,886 | 84.4% | 56 min | 0.76% | B+ |
| All carriers on PHX–SEA | 7,202 | 82.2% | 56 min | 0.69% | B+ |
| Alaska Airlines, whole network | 309,844 | 79.7% | 52 min | 1.20% | B |
Across the year
AS 637 quarter by quarter
AS 637 did not run the same all year. Its best quarter was Jan–Mar 2026 at 89.9% on time and its weakest Jul–Sep 2026 at 70.5%, a swing of 19 points on roughly 91 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 202529 flights—
- Oct–Dec 202592 flights81.5%
- Jan–Mar 202690 flights89.9%
- Apr–Jun 202691 flights89.0%
- Jul–Sep 202662 flights70.5%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
By weekday, AS 637 did best on Saturday at 90.2% on time and worst on Tuesday at 76.9%. Each day rests on about 52 flights, so a gap of 13 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late AS 637 runs when it is late
Most of the lateness is short. 32 of the 58 late arrivals were under half an hour behind, and 16 reached an hour or more.
- 15+ min early89 flights24.6%
- Within 15 min215 flights59.4%
- 15–29 min late32 flights8.8%
- 30–59 min late10 flights2.8%
- 1–2 hours late11 flights3.0%
- 2+ hours late5 flights1.4%
Scale runs 0% to 100%.
Share of 362 completed flights by arrival against schedule.
9 of 41 late departures made up the time and arrived on time, 22% of them. In the other direction, 26 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 SEA.
The worst days
Worst days for AS 637
The latest arrival of the period was on 2 June 2026, 8 hours 45 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 2 June 2026 | 8 hours 45 minutes | Carrier |
| 14 January 2026 | 5 hours 17 minutes | Carrier |
| 18 September 2025 | 4 hours 39 minutes | Carrier |
| 1 March 2026 | 3 hours 24 minutes | Late-arriving aircraft |
| 13 March 2026 | 2 hours 12 minutes | National Airspace System |
Delay causes
Why AS 637 runs late
Carrier accounts for 56% of the 3,443 delay minutes carriers reported here, and the remaining four split what is left.
- 56%Carrier
- 23%Late-arriving aircraft
- 21%National Airspace System
- 0%Extreme weather
- 0%Security
The largest share of delay minutes, 56%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,911 of the 3,443 delay minutes reported here. The split is drawn from 3,443 delay minutes reported on AS 637.
Cancellations are rare at 0.27%, below the national 1.89% 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 4.4% land an hour or more behind schedule, against 8.3% 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.
The 1,107 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
Every one of the 364 flights under AS 637 in the data flew PHX to SEA. 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. 364 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 637
For a booking, read AS 637 as 84.0% on time with 0.27% cancelled over 364 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- PHX to SEA, every carrier and departure
- SEA to PHX, the return direction
- Delta Air Lines 2419 on the same route92.8%
- Alaska Airlines 603 on the same route87.2%
- Alaska Airlines 645 on the same route85.1%
- Alaska Airlines 611 on the same route81.5%
- Delta Air Lines 2444 on the same route94.2%
- Phoenix Sky Harbor International (PHX) delay statistics
- Seattle-Tacoma International (SEA) 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.