Route reliability record
IAD→AUS
Washington to Austin
- Flights
- 1,018
- Period
- September 2025 to August 2026
- Distance
- 1,297 mi
- Carriers
- 3
This route lands a B+, 7 points better than the national rate of 77.3%. 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 rests on 1,018 IAD to AUS flights, with a median arrival 10 minutes early.
Best time to fly IAD to AUS: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 92.2% of the time and Tuesday flights 89.7%, against 83.8% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.3%. That gap is worth roughly 65 fewer late arrivals for every thousand flights.
Key figures
On time
83.8%
Arrivals under 15 minutes late, of 1,008 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
0.79%
National rate is 1.89%
Best carrier
United
84.5% on time across 987 flights
These figures cover 1,018 flights between September 2025 and August 2026. The median arrival is 10 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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Carrier by carrier
Which airline is most reliable on IAD to AUS
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 987 | 84.5% | 73 min | 0.81% | B+ |
| Republic Airwaysthin sample | 11 | 80.0% | 40 min | 0.00% | B+ |
| Allegiant Airthin sample | 20 | 55.0% | 57 min | 0.00% | D+ |
Flight by flight
Flights on IAD to AUS
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.
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.
Best ways to make this trip
The most reliable ways to fly Washington to Austin
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 1 of the top 2 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. IAD → AUSWashington to Austin | United Airlines | 83.8% | 84.5% | 0.81% | 8am–11am, Tue (route) | UA 637 08:25 |
| 2. BWI → AUSBaltimore to Austin | Southwest Airlines | 75.7% | 77.0% | 1.67% | 5am–8am, Tue | — |
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 18 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am308 flights92.2%
- 11am–2pm306 flights84.4%
- 2pm–5pm43 flights74.4%
- 5pm–8pm358 flights77.4%
- 8pm–5am3 flights—
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 92.2% of the time, against 74.4% for the afternoon window. That is 18 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 358 flights scheduled in it.
Explore
Filter IAD to AUS by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On IAD to AUS, the best departure window is 8am–11am at 92.2% on time and the worst is 2pm–5pm at 74.4%, a wide gap of 17.8 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am—
- 8–11am92.2%
- 11am–2pm84.4%
- 2–5pm74.4%
- 5–8pm77.4%
- 8pm–5am—
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 21 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.
August is the worst month at 71.8% on time, 21 points below September, the best at 92.7%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. September was the busiest month here, with 109 flights.
Across the week, Tuesday is the strongest day at 89.7% on time and Saturday the weakest at 79.8%, a spread of 10 points.
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 12,000 reported delay minutes.
- 39%Late-arriving aircraft
- 28%Carrier
- 28%National Airspace System
- 5%Extreme weather
39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 12,000 reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 11,663 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 92.2% on time here.
Cancellations are rare at 0.79%, 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 stage length
What a delay here actually costs
6.8% of arrivals land an hour or more late, close to the national 8.3%, so 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.
The 1,297 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 return leg is a different operation and performs like one: it runs 89.2% on time across 1,019 flights, 5 points above 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 5 points of difference.
One caution: this is a thin sample. 1,018 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.
Work out the risk of missing a connection in AUS after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,018 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 83.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,008 completed flights over 12 months sit behind that.
Common questions
IAD to AUS questions
How often is IAD to AUS 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 16.2% of the 1,018 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
How reliable is IAD to AUS compared with the rest of the country?
83.8% of flights arrive on time here against a national 77.3%, a difference of 7 points in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on IAD to AUS?
The 8am–11am departure window is the strongest at 92.2% on time. The 2pm–5pm window is the weakest at 74.4%, 18 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 August delays on IAD to AUS?
August is the weakest month at 71.8% on time, compared with 92.7% in September. Across the year that is 21 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
- AUS to IAD — the return legseparate record
- Washington Dulles International (IAD) delay statistics
- Austin-Bergstrom International (AUS) delay statistics
- IAD to ATL, a related route78.0%
- DEN to AUS, a related route76.2%
- IAD to DEN, a related route83.1%
- United Airlines on-time record84.5%
- Republic Airways on-time record80.0%
- Allegiant Air on-time record55.0%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. IAD to AUS and AUS to IAD 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.