Route reliability record
AUS→SEA
Austin to Seattle
- Flights
- 2,058
- Period
- July 2025 to June 2026
- Distance
- 1,770 mi
- Carriers
- 3
This route lands a B, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 2,058 AUS to SEA flights, of which Delta Air Lines flew 935 at 84.9% on time.
Best time to fly AUS to SEA: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 88.3% of the time and Wednesday flights 85.1%, against 82.8% for the route overall.
Set against the rest of the country, this route's record is 5 points better than the US average of 77.6%. That gap is worth roughly 52 fewer late arrivals for every thousand flights.
Key figures
On time
82.8%
Arrivals under 15 minutes late, of 2,032 completed flights
Avg delay
69 min
Across delayed arrivals only, not all flights
Cancelled
1.07%
National rate is 1.81%
Best carrier
Delta
84.9% on time across 935 flights
These figures cover 2,058 flights between July 2025 and June 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.
Carrier by carrier
Which airline is most reliable on AUS to SEA
The two carriers here are closely matched: 3 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 935 | 84.9% | 94 min | 1.07% | B |
| Alaska Airlines | 1,096 | 82.0% | 55 min | 1.00% | B |
| Southwest Airlinesthin sample | 27 | 42.3% | 36 min | 3.70% | F− |
No carrier stands out. Delta tops the table at 84.9%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on AUS to SEA
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Best ways to make this trip
The most reliable ways to fly Austin to Seattle
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. AUS → SEAAustin to Seattle | Delta Air Lines | 84.0% | 84.9% | 1.07% | 5am–8am, Sat | DL 780 06:00 |
| 2. AUS → SEAAustin to Seattle | Alaska Airlines | 81.2% | 82.0% | 1.00% | 2pm–5pm, Wed | AS 503 13:36 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 14 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am605 flights88.3%
- 8am–11am134 flights87.3%
- 11am–2pm515 flights85.5%
- 2pm–5pm172 flights82.7%
- 5pm–8pm608 flights74.5%
- 8pm–5am24 flights—
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 88.3% of the time, against 74.5% for the evening window. That is 14 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 608 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 22 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
December is the weak month at 70.2% on time, against 91.8% in April. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 208 flights.
Across the week, Wednesday is the strongest day at 85.1% on time and Sunday the weakest at 79.3%. 6 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 24,000 reported delay minutes.
- 39%Carrier
- 38%Late-arriving aircraft
- 17%National Airspace System
- 5%Extreme weather
- 1%Security
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 24,000 reported delay minutes here, that single category outweighs weather by 8 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 24,221 reported delay minutes.
The largest share of delay minutes, 39%, 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 9,424 of the 24,000 delay minutes reported here.
Cancellations sit at 1.07% against a national 1.81%, which is ordinary. Diversions add another 0.19%.
Connections and stage length
What a delay here actually costs
5.6% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
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.
The return leg is a different operation and performs like one: it runs 79.1% on time across 2,059 flights, 4 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
The sample behind these figures is 2,058 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in SEA after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 91.8% on time and December 70.2%, a swing of 22 points. If the dates move at all, move them out of December before you think about anything else. 2,032 completed flights over 12 months sit behind that.
Common questions
AUS to SEA questions
How often is AUS to SEA delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.2% of the 2,058 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on AUS to SEA?
Delta Air Lines leads at 84.9% on time across 935 flights. Alaska Airlines is at the other end on 82.0%, a gap of 3 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on AUS to SEA?
The 5am–8am departure window is the strongest at 88.3% on time. The 5pm–8pm window is the weakest at 74.5%, 14 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are December delays on AUS to SEA?
December is the weakest month at 70.2% on time, compared with 91.8% in April. Across the year that is 22 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SEA to AUS — the return legseparate record
- Austin-Bergstrom International (AUS) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on AUS to SEA84.9%
- Alaska Airlines on AUS to SEA82.0%
- AUS to DEN, a related route78.4%
- LAX to SEA, a related route85.4%
- AUS to DFW, a related route73.8%
- Delta Air Lines on-time record84.9%
- Alaska Airlines on-time record82.0%
- Southwest Airlines on-time record42.3%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. AUS to SEA and SEA to AUS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.