Carrier route record
WNAUS→BOS
Southwest Airlines · Austin to Boston
- Flights
- 282
- Period
- July 2025 to June 2026
- Share of route
- 17%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on AUS to BOS earns an F, which is as low as this site's scale goes for a reason. Only 54.7% of flights arrive inside the 15-minute window, 23 points worse than the national rate of 77.6%. Late arrivals average roughly 55 minutes. Treat any tight connection here as a coin flip. That rests on 282 flights, with a median arrival 10 minutes late.
The national on-time rate over the same period is 77.6%, so Southwest on AUS to BOS runs 23 points behind the country as a whole. Across a thousand flights that is about 229 extra late arrivals.
Key figures
On time
54.7%
Arrivals under 15 minutes late, of 276 completed flights
Avg delay
54 min
Across delayed arrivals only, not all flights
Cancelled
1.77%
National rate is 1.81%
Whole route
65.4%
Every carrier on AUS to BOS, 1,634 flights
These figures cover 282 flights between July 2025 and June 2026. Beyond the headline rate, 14.1% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Southwest against every carrier on AUS to BOS
Southwest flew 282 of the 1,634 flights on AUS to BOS, about 17% of it. Its 54.7% on time is 11 points worse than the route as a whole, which runs 65.4%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Delta at 70.9% to Southwest at 54.7%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
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 |
|---|---|---|---|---|---|
| Delta Air Lines | 988 | 70.9% | 91 min | 2.73% | C |
| JetBlue Airwaysthin sample | 364 | 58.9% | 84 min | 1.65% | D |
| Southwest Airlines (this page)thin sample | 282 | 54.7% | 54 min | 1.77% | F |
Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 40 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am72 flights66.7%
- 11am–2pm170 flights56.0%
- 2pm–5pm40 flights26.3%
- 5pm–8pm—
- 8pm–5am—
Scale runs 20% to 70%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 66.7% of the time, against 26.3% for the afternoon window. That is 40 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 170 flights scheduled in it.
Across the year
Southwest on AUS to BOS through the year
- Jul–Sep 202584 flights62.2%
- Oct–Dec 202564 flights49.2%
- Jan–Mar 202652 flights49.0%
- Apr–Jun 202682 flights54.9%
Scale runs 40% to 70%. Rows with fewer than 30 flights show a dash.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 54.7% on time across 282 flights.
Southwest on AUS to BOS did not run the same all year. Its best quarter was Jul–Sep 2025 at 62.2% on time and its weakest Jan–Mar 2026 at 49.0%, a swing of 13 points on roughly 71 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.
Across the week, Tuesday is the strongest day at 76.9% on time and Thursday the weakest at 45.2%. 32 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. National Airspace System accounts for 45% of the 6,710 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 45%National Airspace System
- 32%Late-arriving aircraft
- 23%Carrier
- 0%Security
45% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,994 minutes out of 6,710, against a national NAS share of 21%. The split is drawn from 6,710 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 66.7% on time here.
Cancellations sit at 1.77% against a national 1.81%, which is ordinary. Diversions add another 0.35%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 14.1% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
At 1,698 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 62.5% on time across 282 flights, 8 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 8 points of difference.
One caution: this is a thin sample. 282 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 Southwest on AUS to BOS
Put together: treat all of this as provisional. 282 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 54.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 276 completed flights over 12 months sit behind that.
Related
Where to go next
- AUS to BOS, every carrier
- Southwest on BOS to AUS, the return leg
- Delta Air Lines on AUS to BOS70.9%
- JetBlue Airways on AUS to BOS58.9%
- Southwest Airlines network-wide record
- Austin-Bergstrom International (AUS) delay statistics
- Boston Logan International (BOS) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.