Flight number record
AS 637
Alaska Airlines · Phoenix to Seattle
- Route
- PHX → SEA
- Departs
- 10:46
- Flights
- 364
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s AS 637, check with Alaska Airlines.
AS 637 earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 10 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 364 flights, with a median arrival 7 minutes early.
Set against the rest of the country, AS 637's record is 10 points better than the US average of 77.6%. That gap is worth roughly 100 fewer late arrivals for every thousand flights.
Key figures
On time
87.6%
Arrivals under 15 minutes late, of 362 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.55%
National rate is 1.81%
1 hour+ late
3.6%
National rate is 8.1%
These figures cover 364 flights between July 2025 and June 2026. The median arrival is 7 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 637 flies
AS 637 flies PHX to SEA without a single fixed slot. Its most common scheduled departure was 10:46, used on 50 of 364 flights, with 09:00 (50 flights) and 10:50 (44 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 10:4650 flights13.7%
- Departs 09:0050 flights13.7%
- Departs 10:5044 flights12.1%
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 10:46 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and AS 637 runs 4 points better at 87.6%. 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 637 next to PHX to SEA
Every carrier on PHX to SEA combined arrived on time 82.7% of the time across 7,269 flights, so AS 637 is 5 points ahead of it. Alaska flew 2,903 flights on the same city pair under all its flight numbers, including this one, and those ran 84.9% on time. Across its whole network Alaska Airlines managed 79.1%, which this flight beats by 9 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| AS 637thin sample | 364 | 87.6% | 70 min | 0.55% | A+ |
| All Alaska Airlines on PHX–SEA | 2,903 | 84.9% | 56 min | 0.76% | B+ |
| All carriers on PHX–SEA | 7,269 | 82.7% | 55 min | 0.65% | B+ |
| Alaska Airlines, whole network | 293,372 | 79.1% | 52 min | 1.28% | B |
Across the year
AS 637 quarter by quarter
Quarter by quarter AS 637 held fairly steady: 90.0% in Jul–Sep 2025, 81.5% in Oct–Dec 2025, 89.9% in Jan–Mar 2026 and 89.0% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202591 flights90.0%
- Oct–Dec 202592 flights81.5%
- Jan–Mar 202690 flights89.9%
- Apr–Jun 202691 flights89.0%
Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.
By weekday, AS 637 ranged from 80.4% on Wednesday to 92.2% on Saturday. With about 52 flights behind each day, a spread of 12 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why AS 637 runs late
One category carries most of the weight here. Carrier accounts for 52% of the 3,128 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.
- 52%Carrier
- 33%Late-arriving aircraft
- 14%National Airspace System
- 1%Extreme weather
- 0%Security
The largest share of delay minutes, 52%, 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 1,639 of the 3,128 delay minutes reported here. The split is drawn from 3,128 delay minutes reported on AS 637.
Cancellations are rare at 0.55%, 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 3.6% 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.
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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
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, AS 637 has one of the better records a US domestic flight can show: 87.6% on time and 0.55% cancelled. That is a base rate, not a promise about any single 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%
- Delta Air Lines 2444 on the same route95.2%
- Alaska Airlines 603 on the same route88.7%
- Alaska Airlines 645 on the same route84.2%
- Alaska Airlines 611 on the same route79.8%
- 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
- Why the first flight of the morning is statistically safest
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.