Carrier route record

DLAUS→BOS

Delta Air Lines · Austin to Boston

Flights: 1,001
Period: September 2025 to August 2026
Share of route: 58%
Carriers: 3

Historical statistics for September 2025 to August 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, 8 points worse than the national rate of 77.3%. The late ones land an hour and a half behind schedule. That rests on 1,001 flights, with a median arrival 1 minute early.

The national on-time rate over the same period is 77.3%, so Delta on AUS to BOS runs 8 points behind the country as a whole. Across a thousand flights that is about 77 extra late arrivals.

On time

69.6%

Arrivals under 15 minutes late, of 971 completed flights

Avg delay

90 min

Across delayed arrivals only, not all flights

Cancelled

2.70%

National rate is 1.89%

Whole route

64.5%

Every carrier on AUS to BOS, 1,713 flights

These figures cover 1,001 flights between September 2025 and August 2026. Beyond the headline rate, 13.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Carrier by carrier

Delta against every carrier on AUS to BOS

Delta flew 1,001 of the 1,713 flights on AUS to BOS, most of the route. Its 69.6% on time is 5 points better than the route as a whole, which runs 64.5%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 69.6% to Southwest at 54.8%. 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.

On-time performance by carrier on AUS to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	1,001	69.6%	90 min	2.70%	C
JetBlue Airways	426	59.0%	82 min	3.29%	D−
Southwest Airlinesthin sample	286	54.8%	52 min	1.75%	F

Flight by flight

Delta flight numbers on AUS to BOS

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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 55 points, against half a point between the best and worst carrier.

5am–8am346 flights87.5%
8am–11am16 flights—
11am–2pm37 flights32.4%
2pm–5pm310 flights59.7%
5pm–8pm292 flights62.5%
8pm–5am—

Scale runs 25% 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 32.4% on time against 87.5% 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 74.5% on time and Thursday the weakest at 65.1%, a spread of 9 points.

Arrival by arrival

How late Delta on AUS to BOS runs when it is late

The 295 late arrivals split 87 under half an hour, 80 between 30 and 60 minutes, and 128 an hour or more.

15+ min early225 flights23.2%
Within 15 min451 flights46.4%
15–29 min late87 flights9.0%
30–59 min late80 flights8.2%
1–2 hours late69 flights7.1%
2+ hours late59 flights6.1%

Scale runs 0% to 100%.

Share of 971 completed flights by arrival against schedule.

Time lost at the gate mostly stays lost. Of 251 departures that left 15 minutes late or more, only 25 made it up before arrival. In the other direction, 69 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 BOS.

The worst days

Worst days for Delta on AUS to BOS

The latest arrival of the period was on 17 April 2026, 16 hours 45 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.

The latest arrivals of Delta on AUS to BOS in the period
Date	Arrived late by	Largest filed cause
17 April 2026	16 hours 45 minutes	Carrier
24 July 2026	15 hours 7 minutes	Carrier
24 February 2026	11 hours 27 minutes	Carrier
26 September 2025	11 hours 1 minute	Carrier
25 October 2025	8 hours 54 minutes	Late-arriving aircraft

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 27,000 reported delay minutes.

Carrier
36%
National Airspace System
32%
Late-arriving aircraft
30%
Extreme weather
1%

The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 9,671 of the 27,000 delay minutes reported here. The split is drawn from 26,582 reported delay minutes.

32% 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 8,621 minutes out of 27,000, against a national NAS share of 21%.

Cancellations run at 2.70%, against 1.89% nationally. That is about 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

13.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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 73.7% on time across 1,001 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. 1,001 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. 1,001 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 69.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 971 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures