Carrier route record

DLBOS→AUS

Delta Air Lines · Boston to Austin

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 BOS to AUS sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 3 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 8 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on BOS to AUS from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

74.9%

Arrivals under 15 minutes late, of 960 completed flights

Avg delay

93 min

Across delayed arrivals only, not all flights

Cancelled

2.63%

National rate is 1.81%

Whole route

72.2%

Every carrier on BOS to AUS, 1,634 flights

These figures cover 988 flights between July 2025 and June 2026. Beyond the headline rate, 10.9% 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 BOS to AUS

Delta flew 988 of the 1,634 flights on BOS to AUS, most of the route. Its 74.9% on time is 3 points better than the route as a whole, which runs 72.2%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 74.9% to Southwest at 62.5%. 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 BOS to AUS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	988	74.9%	93 min	2.63%	C
JetBlue Airwaysthin sample	364	72.5%	61 min	1.10%	C
Southwest Airlinesthin sample	282	62.5%	54 min	0.71%	D+

Flight by flight

Delta flight numbers on BOS to AUS

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 24 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–8am362 flights84.8%
8am–11am3 flights—
11am–2pm271 flights77.0%
2pm–5pm30 flights—
5pm–8pm320 flights61.1%
8pm–5am2 flights—

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 61.1% on time, against 84.8% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5am–8am window is the busiest, with 362 flights scheduled in it.

Across the year

Delta on BOS to AUS through the year

Darker means more delays. Figures are on-time percentages.April best, September worst

April is the best month on the calendar at 87.8% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. March was the busiest month here, with 89 flights.

Across the week, Wednesday is the strongest day at 77.2% on time and Sunday the weakest at 70.5%. 7 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 47% of the 22,000 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.

Carrier
47%
Late-arriving aircraft
30%
National Airspace System
21%
Extreme weather
3%

The largest share of delay minutes, 47%, 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 10,000 of the 22,000 delay minutes reported here. The split is drawn from 22,394 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 84.8% on time here.

Cancellations run at 2.63%, against 1.81% 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.9% 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 70.9% on time across 988 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.

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 BOS to AUS

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 74.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 960 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