Flight number record
AS 503
Alaska Airlines · Austin to Seattle
- Route
- AUS → SEA
- Departs
- 16:17
- Flights
- 335
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s AS 503, check with Alaska Airlines.
AS 503 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 335 flights, with a median arrival 8 minutes early.
Set against the rest of the country, AS 503'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 331 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
0.90%
National rate is 1.89%
1 hour+ late
4.8%
National rate is 8.3%
These figures cover 335 flights between September 2025 and August 2026. The median arrival is 8 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Schedule
When AS 503 flies
AS 503 flies AUS to SEA without a single fixed slot. Its most common scheduled departure was 16:17, used on 70 of 335 flights, with 13:33 (46 flights) and 12:30 (35 flights) next.
- Departs 16:1770 flights20.9%
- Departs 13:3346 flights13.7%
- Departs 12:3035 flights10.4%
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 16:17 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and AS 503 runs 12 points better at 84.0%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Against the route
AS 503 next to AUS to SEA
Every carrier on AUS to SEA combined arrived on time 81.3% of the time across 2,089 flights, so AS 503 is 3 points ahead of it. Alaska flew 1,051 flights on the same city pair under all its flight numbers, including this one, and those ran 81.8% 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 503thin sample | 335 | 84.0% | 62 min | 0.90% | B+ |
| All Alaska Airlines on AUS–SEA | 1,051 | 81.8% | 50 min | 0.76% | B+ |
| All carriers on AUS–SEA | 2,089 | 81.3% | 61 min | 0.86% | B+ |
| Alaska Airlines, whole network | 309,844 | 79.7% | 52 min | 1.20% | B |
Across the year
AS 503 quarter by quarter
AS 503 did not run the same all year. Its best quarter was Apr–Jun 2026 at 93.5% on time and its weakest Jul–Sep 2026 at 75.8%, a swing of 18 points on roughly 67 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 202530 flights83.3%
- Oct–Dec 202592 flights81.5%
- Jan–Mar 202688 flights85.9%
- Apr–Jun 202663 flights93.5%
- Jul–Sep 202662 flights75.8%
Scale runs 65% to 100%.
By weekday, AS 503 did best on Wednesday at 89.6% on time and worst on Thursday at 77.1%. Each day rests on about 48 flights, so a gap of 13 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late AS 503 runs when it is late
AS 503 often beats the schedule: 110 of 331 completed flights, 33%, arrived 15 minutes or more early. The 53 late arrivals split 26 under half an hour, 11 between 30 and 60 minutes, and 16 an hour or more.
- 15+ min early110 flights33.2%
- Within 15 min168 flights50.8%
- 15–29 min late26 flights7.9%
- 30–59 min late11 flights3.3%
- 1–2 hours late8 flights2.4%
- 2+ hours late8 flights2.4%
Scale runs 0% to 100%.
Share of 331 completed flights by arrival against schedule.
A late pushback is often recovered here: of 60 departures that left 15 minutes late or more, 25 still arrived on time. In the other direction, 18 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 503
The latest arrival of the period was on 12 February 2026, 5 hours 26 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On four of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 12 February 2026 | 5 hours 26 minutes | Carrier |
| 21 June 2026 | 5 hours 7 minutes | Late-arriving aircraft |
| 19 December 2025 | 3 hours 22 minutes | Late-arriving aircraft |
| 25 August 2026 | 3 hours 20 minutes | Late-arriving aircraft |
| 6 November 2025 | 3 hours 9 minutes | Late-arriving aircraft |
Delay causes
Why AS 503 runs late
Late-arriving aircraft accounts for 51% of the 3,259 delay minutes carriers reported here, and the remaining four split what is left.
- 51%Late-arriving aircraft
- 27%Carrier
- 16%National Airspace System
- 3%Extreme weather
- 3%Security
51% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,259 reported delay minutes here, that single category outweighs weather by 17 to one. The split is drawn from 3,259 delay minutes reported on AS 503.
Cancellations sit at 0.90% against a national 1.89%, which is ordinary. Diversions add another 0.30%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 4.8% 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.
At 1,770 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
Every one of the 335 flights under AS 503 in the data flew AUS 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. 335 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 503
For a booking, read AS 503 as 84.0% on time with 0.90% cancelled over 335 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- AUS to SEA, every carrier and departure
- SEA to AUS, the return direction
- Delta Air Lines 780 on the same route92.9%
- Alaska Airlines 339 on the same route74.5%
- Austin-Bergstrom International (AUS) 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.