Flight number record
AS 643
Alaska Airlines · Denver to Seattle
- Route
- DEN → SEA
- Departs
- 07:00
- Flights
- 294
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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 12 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 294 flights, with a median arrival 11 minutes early.
Set against the rest of the country, AS 643's record is 12 points better than the US average of 77.3%. That gap is worth roughly 122 fewer late arrivals for every thousand flights.
Key figures
On time
89.5%
Arrivals under 15 minutes late, of 294 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
2.7%
National rate is 8.3%
These figures cover 294 flights between September 2025 and August 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.
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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 294 flights, with 06:02 (70 flights) and 08:00 (41 flights) next.
- Departs 07:00131 flights44.6%
- Departs 06:0270 flights23.8%
- Departs 08:0041 flights13.9%
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 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 89.5%. 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 643 next to DEN to SEA
Every carrier on DEN to SEA combined arrived on time 74.5% of the time across 6,328 flights, so AS 643 is 15 points ahead of it. Alaska flew 1,551 flights on the same city pair under all its flight numbers, including this one, and those ran 74.9% on time. Across its whole network Alaska Airlines managed 79.7%, which this flight beats by 10 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| AS 643thin sample | 294 | 89.5% | 66 min | 0.00% | A+ |
| All Alaska Airlines on DEN–SEA | 1,551 | 74.9% | 58 min | 0.71% | C+ |
| All carriers on DEN–SEA | 6,328 | 74.5% | 58 min | 0.60% | C+ |
| Alaska Airlines, whole network | 309,844 | 79.7% | 52 min | 1.20% | 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.
- Oct–Dec 202564 flights81.2%
- Jan–Mar 202690 flights90.0%
- Apr–Jun 202691 flights93.4%
- Jul–Sep 202649 flights91.8%
Scale runs 75% to 100%.
By weekday, AS 643 did best on Tuesday at 97.7% on time and worst on Sunday at 81.4%. Each day rests on about 42 flights, so a gap of 16 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late AS 643 runs when it is late
AS 643 often beats the schedule: 128 of 294 completed flights, 44%, arrived 15 minutes or more early. The 31 late arrivals split 14 under half an hour, 9 between 30 and 60 minutes, and 8 an hour or more.
- 15+ min early128 flights43.5%
- Within 15 min135 flights45.9%
- 15–29 min late14 flights4.8%
- 30–59 min late9 flights3.1%
- 1–2 hours late2 flights0.7%
- 2+ hours late6 flights2.0%
Scale runs 0% to 100%.
Share of 294 completed flights by arrival against schedule.
A late pushback is often recovered here: of 23 departures that left 15 minutes late or more, 7 still arrived on time. In the other direction, 15 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 643
The latest arrival of the period was on 10 July 2026, 4 hours 52 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on five of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 10 July 2026 | 4 hours 52 minutes | Carrier |
| 25 June 2026 | 4 hours 22 minutes | Carrier |
| 20 June 2026 | 4 hours 12 minutes | Carrier |
| 18 July 2026 | 2 hours 30 minutes | Carrier |
| 27 November 2025 | 2 hours 15 minutes | Carrier |
Delay causes
Why AS 643 runs late
Carrier accounts for 75% of the 2,048 delay minutes carriers reported here, and the remaining four split what is left.
- 75%Carrier
- 25%National Airspace System
The largest share of delay minutes, 75%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,530 of the 2,048 delay minutes reported here. The split is drawn from 2,048 delay minutes reported on AS 643.
Cancellations are rare at 0.00%, below the national 1.89% 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 2.7% 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 1,024 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.
The same number turns up on one other city pair in the data, including EWR to PDX (13), but none flew often enough under AS 643 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DEN to SEA only.
One caution: this is a thin sample. 294 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: 89.5% 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 route91.9%
- United Airlines 2013 on the same route77.9%
- United Airlines 1424 on the same route85.7%
- 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 7.05 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.