Carrier route record

DLAUS→BOS

Delta Air Lines · Austin to Boston

Flights: 988
Period: July 2025 to June 2026
Share of route: 60%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on AUS to BOS sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 988 flights, with a median arrival 3 minutes early.

The national on-time rate over the same period is 77.6%, so Delta on AUS to BOS runs 7 points behind the country as a whole. Across a thousand flights that is about 67 extra late arrivals.

On time

70.9%

Arrivals under 15 minutes late, of 958 completed flights

Avg delay

91 min

Across delayed arrivals only, not all flights

Cancelled

2.73%

National rate is 1.81%

Whole route

65.4%

Every carrier on AUS to BOS, 1,634 flights

These figures cover 988 flights between July 2025 and June 2026. Beyond the headline rate, 12.8% 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

Delta against every carrier on AUS to BOS

Delta flew 988 of the 1,634 flights on AUS to BOS, most of the route. Its 70.9% on time is 6 points better than the route as a whole, which runs 65.4%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 70.9% to Southwest at 54.7%. Two 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.

On-time performance by carrier on AUS to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	988	70.9%	91 min	2.73%	C
JetBlue Airwaysthin sample	364	58.9%	84 min	1.65%	D
Southwest Airlinesthin sample	282	54.7%	54 min	1.77%	F

Flight by flight

Delta flight numbers on AUS to BOS

Departure window

When Delta runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 39 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–8am346 flights87.6%
8am–11am16 flights—
11am–2pm89 flights48.9%
2pm–5pm257 flights62.8%
5pm–8pm280 flights63.3%
8pm–5am—

Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.

The weak window here is the middle of the day, not the evening: 11am–2pm runs 48.9% on time against 87.6% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 5am–8am window is the busiest, with 346 flights scheduled in it.

Across the year

Delta on AUS to BOS through the year

Darker means more delays. Figures are on-time percentages.January best, October worst

Delays peak in October, when the on-time rate falls to 59.1%. January is the strongest month at 81.5%. Moving a flexible trip across that boundary buys 22 points. March was the busiest month here, with 89 flights.

Across the week, Saturday is the strongest day at 77.5% on time and Thursday the weakest at 63.2%. 14 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

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 25,000 reported delay minutes.

Carrier
36%
Late-arriving aircraft
34%
National Airspace System
30%
Extreme weather
1%

The largest share of delay minutes, 36%, 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 9,073 of the 25,000 delay minutes reported here. The split is drawn from 25,485 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 87.6% on time here.

Cancellations run at 2.73%, against 1.81% nationally. That is roughly one flight in 40 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

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. 12.8% 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 74.9% on time across 988 flights, 4 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 4 points of difference.

One caution: this is a thin sample. 988 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 Delta on AUS to BOS

Put together: treat all of this as provisional. 988 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 70.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 958 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures