Flight number record
AS 634
Alaska Airlines · Las Vegas to San Francisco
- Route
- LAS → SFO
- Departs
- 18:03
- Flights
- 281
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s AS 634, check with Alaska Airlines.
AS 634 earns an F+, which is as low as this site's scale goes for a reason. Only 53.9% of flights arrive inside the 15-minute window, 23 points worse than the national rate of 77.3%. Late arrivals average about 55 minutes. Treat any tight connection here as a coin flip. That rests on 281 flights, with a median arrival 9 minutes late.
The national on-time rate over the same period is 77.3%, so AS 634 runs 23 points behind the country as a whole. Across a thousand flights that is about 234 extra late arrivals.
Key figures
On time
53.9%
Arrivals under 15 minutes late, of 280 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.36%
National rate is 1.89%
1 hour+ late
14.6%
National rate is 8.3%
These figures cover 281 flights between September 2025 and August 2026. Beyond the headline rate, 14.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When AS 634 flies
AS 634 flies LAS to SFO without a single fixed slot. Its most common scheduled departure was 18:03, used on 59 of 281 flights, with 15:39 (44 flights) and 15:34 (35 flights) next.
- Departs 18:0359 flights21.0%
- Departs 15:3944 flights15.7%
- Departs 15:3435 flights12.5%
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 18:03 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and AS 634 runs 14 points worse at 53.9%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
AS 634 next to LAS to SFO
Every carrier on LAS to SFO combined arrived on time 58.0% of the time across 6,137 flights, so AS 634 is 4 points behind it. Alaska flew 1,102 flights on the same city pair under all its flight numbers, including this one, and those ran 63.3% on time. Across its whole network Alaska Airlines managed 79.7%, which this flight trails by 26 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| AS 634thin sample | 281 | 53.9% | 55 min | 0.36% | F+ |
| All Alaska Airlines on LAS–SFO | 1,102 | 63.3% | 52 min | 0.91% | D+ |
| All carriers on LAS–SFO | 6,137 | 58.0% | 60 min | 0.77% | D+ |
| Alaska Airlines, whole network | 309,844 | 79.7% | 52 min | 1.20% | B |
Across the year
AS 634 quarter by quarter
AS 634 did not run the same all year. Its best quarter was Jan–Mar 2026 at 81.2% on time and its weakest Apr–Jun 2026 at 34.1%, a swing of 47 points on roughly 70 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 202526 flights—
- Oct–Dec 202564 flights67.2%
- Jan–Mar 202648 flights81.2%
- Apr–Jun 202682 flights34.1%
- Jul–Sep 202661 flights43.3%
Scale runs 25% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, AS 634 did best on Tuesday at 63.9% on time and worst on Sunday at 38.6%. Each day rests on about 40 flights, so a gap of 25 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late AS 634 runs when it is late
The 129 late arrivals split 29 under half an hour, 59 between 30 and 60 minutes, and 41 an hour or more.
- 15+ min early47 flights16.8%
- Within 15 min104 flights37.1%
- 15–29 min late29 flights10.4%
- 30–59 min late59 flights21.1%
- 1–2 hours late33 flights11.8%
- 2+ hours late8 flights2.9%
Scale runs 0% to 100%.
Share of 280 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 113 departures that left 15 minutes late or more, only 12 made it up before arrival. In the other direction, 28 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 SFO.
The worst days
Worst days for AS 634
The latest arrival of the period was on 14 August 2026, 4 hours 7 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. On four of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 14 August 2026 | 4 hours 7 minutes | National Airspace System |
| 28 May 2026 | 3 hours 27 minutes | Late-arriving aircraft |
| 24 August 2026 | 2 hours 47 minutes | Late-arriving aircraft |
| 19 July 2026 | 2 hours 23 minutes | Late-arriving aircraft |
| 18 November 2025 | 2 hours 22 minutes | Late-arriving aircraft |
Delay causes
Why AS 634 runs late
National Airspace System accounts for 49% of the 7,041 delay minutes carriers reported here, and the remaining four split what is left.
- 49%National Airspace System
- 43%Late-arriving aircraft
- 6%Carrier
- 1%Extreme weather
- 0%Security
43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 7,041 reported delay minutes here, that single category outweighs weather by 29 to one. The split is drawn from 7,041 delay minutes reported on AS 634.
Cancellations are rare at 0.36%, 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
14.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The same number turns up on one other city pair in the data, including SFO to LAS (63), but none flew often enough under AS 634 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to LAS to SFO only.
One caution: this is a thin sample. 281 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 634
For a booking, AS 634 is a flight to put a long connection behind. 14.6% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- LAS to SFO, every carrier and departure
- SFO to LAS, the return direction
- United Airlines 574 on the same route66.1%
- United Airlines 2356 on the same route59.1%
- Frontier Airlines 4401 on the same route48.0%
- United Airlines 2047 on the same route67.7%
- United Airlines 1799 on the same route52.8%
- Frontier Airlines 3801 on the same route60.1%
- Harry Reid International (LAS) delay statistics
- San Francisco International (SFO) 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.