Flight number record

DL 1233

Delta Air Lines · New York to Austin

Route: JFK → AUS
Departs: 18:10
Flights: 364
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1233, check with Delta Air Lines.

DL 1233 lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 364 flights, with a median arrival 11 minutes early.

On time

76.3%

Arrivals under 15 minutes late, of 354 completed flights

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

2.47%

National rate is 1.81%

1 hour+ late

8.2%

National rate is 8.1%

These figures cover 364 flights between July 2025 and June 2026. Beyond the headline rate, 8.2% 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.

Schedule

When DL 1233 flies

DL 1233 flies JFK to AUS without a single fixed slot. Its most common scheduled departure was 18:10, used on 64 of 364 flights, with 18:15 (40 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 18:1064 flights17.6%
Departs 18:1540 flights11.0%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 18:10 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and DL 1233 runs 8 points better at 76.3%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

DL 1233 next to JFK to AUS

Every carrier on JFK to AUS combined arrived on time 82.2% of the time across 2,160 flights, so DL 1233 is 6 points behind it. Delta flew 1,278 flights on the same city pair under all its flight numbers, including this one, and those ran 83.7% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 5 points.

DL 1233 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1233thin sample	364	76.3%	68 min	2.47%	B
All Delta Air Lines on JFK–AUS	1,278	83.7%	62 min	2.11%	B
All carriers on JFK–AUS	2,160	82.2%	91 min	2.59%	B
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1233 quarter by quarter

DL 1233 did not run the same all year. Its best quarter was Apr–Jun 2026 at 82.2% on time and its weakest Oct–Dec 2025 at 70.5%, a swing of 12 points on roughly 91 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.

Jul–Sep 202592 flights71.4%
Oct–Dec 202591 flights70.5%
Jan–Mar 202690 flights81.2%
Apr–Jun 202691 flights82.2%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1233 did best on Friday at 86.0% on time and worst on Sunday at 67.3%. Each day rests on about 52 flights, so a gap of 19 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1233 runs late

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 5,721 reported delay minutes.

Late-arriving aircraft
36%
National Airspace System
34%
Carrier
23%
Extreme weather
6%

36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 5,721 reported delay minutes here, that single category outweighs weather by 6 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 5,721 delay minutes reported on DL 1233.

Cancellations sit at 2.47% against a national 1.81%, which is ordinary. Diversions add another 0.27%.

Connections and routes

What a delay on this flight costs

8.2% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says 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.

At 1,521 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.

Every one of the 364 flights under DL 1233 in the data flew JFK to AUS. The number was not reused on any other city pair, which makes this a clean record of one route.

One caution: this is a thin sample. 364 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 DL 1233

For a booking, DL 1233 is one of the weaker ways to fly JFK to AUS: 6 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.

Where to go next

A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.

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