Flight number record
AS 643
Alaska Airlines · Denver to Seattle
- Route
- DEN → SEA
- Departs
- 07:00
- Flights
- 295
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s AS 643, check with Alaska Airlines.
AS 643 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 11 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 295 flights, with a median arrival 11 minutes early.
Set against the rest of the country, AS 643's record is 11 points better than the US average of 77.6%. That gap is worth roughly 105 fewer late arrivals for every thousand flights.
Key figures
On time
88.1%
Arrivals under 15 minutes late, of 295 completed flights
Avg delay
77 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.81%
1 hour+ late
3.7%
National rate is 8.1%
These figures cover 295 flights between July 2025 and June 2026. The median arrival is 11 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 643 flies
AS 643 flies DEN to SEA without a single fixed slot. Its most common scheduled departure was 07:00, used on 131 of 295 flights, with 06:00 (86 flights) and 08:00 (41 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 07:00131 flights44.4%
- Departs 06:0086 flights29.2%
- Departs 08:0041 flights13.9%
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 07:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and AS 643 runs level with that at 88.1%. 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 643 next to DEN to SEA
Every carrier on DEN to SEA combined arrived on time 73.9% of the time across 6,309 flights, so AS 643 is 14 points ahead of it. Alaska flew 1,558 flights on the same city pair under all its flight numbers, including this one, and those ran 73.8% 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 643thin sample | 295 | 88.1% | 77 min | 0.00% | A+ |
| All Alaska Airlines on DEN–SEA | 1,558 | 73.8% | 57 min | 0.96% | C+ |
| All carriers on DEN–SEA | 6,309 | 73.9% | 57 min | 0.76% | C+ |
| Alaska Airlines, whole network | 293,372 | 79.1% | 52 min | 1.28% | B |
Across the year
AS 643 quarter by quarter
AS 643 did not run the same all year. Its best quarter was Apr–Jun 2026 at 93.4% on time and its weakest Oct–Dec 2025 at 81.2%, a swing of 12 points on roughly 74 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 202550 flights84.0%
- Oct–Dec 202564 flights81.2%
- Jan–Mar 202690 flights90.0%
- Apr–Jun 202691 flights93.4%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, AS 643 did best on Tuesday at 95.5% on time and worst on Sunday at 79.1%. Each day rests on about 42 flights, so a gap of 16 points is worth noticing but could still narrow in another year.
Delay causes
Why AS 643 runs late
One category carries most of the weight here. Carrier accounts for 61% of the 2,688 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.
- 61%Carrier
- 37%National Airspace System
- 2%Extreme weather
The largest share of delay minutes, 61%, 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 1,634 of the 2,688 delay minutes reported here. The split is drawn from 2,688 delay minutes reported on AS 643.
Cancellations are rare at 0.00%, below the national 1.81% and low enough to earn the plus on the grade. Almost no flights are 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 3.7% 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 1,024 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 295 flights under AS 643 in the data flew DEN 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. 295 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 643
For a booking, AS 643 has one of the better records a US domestic flight can show: 88.1% on time and 0.00% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- DEN to SEA, every carrier and departure
- SEA to DEN, the return direction
- Delta Air Lines 1731 on the same route89.4%
- United Airlines 2271 on the same route90.7%
- Alaska Airlines 682 on the same route81.2%
- Denver International (DEN) 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
- The best time of day to fly, according to 7.04 million flight records
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.