Flight number record

DL 1234

Delta Air Lines · Atlanta to Miami

Route: ATL → MIA
Departs: 22:30
Flights: 276
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1234, check with Delta Air Lines.

DL 1234 draws a D+. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 276 flights, with a median arrival 6 minutes late.

The national on-time rate over the same period is 77.6%, so DL 1234 runs 15 points behind the country as a whole. Across a thousand flights that is about 151 extra late arrivals.

On time

62.5%

Arrivals under 15 minutes late, of 275 completed flights

Avg delay

63 min

Across delayed arrivals only, not all flights

Cancelled

0.36%

National rate is 1.81%

1 hour+ late

12.4%

National rate is 8.1%

These figures cover 276 flights between July 2025 and June 2026. Beyond the headline rate, 12.4% 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 1234 flies

DL 1234 flies ATL to MIA without a single fixed slot. Its most common scheduled departure was 22:30, used on 56 of 276 flights, with 20:30 (34 flights) and 22:38 (33 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 22:3056 flights20.3%
Departs 20:3034 flights12.3%
Departs 22:3833 flights12.0%

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 22:30 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and DL 1234 runs 8 points worse at 62.5%. 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 1234 next to ATL to MIA

Every carrier on ATL to MIA combined arrived on time 71.0% of the time across 6,229 flights, so DL 1234 is 9 points behind it. Delta flew 3,298 flights on the same city pair under all its flight numbers, including this one, and those ran 70.3% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 19 points.

DL 1234 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1234thin sample	276	62.5%	63 min	0.36%	D+
All Delta Air Lines on ATL–MIA	3,298	70.3%	56 min	1.43%	C
All carriers on ATL–MIA	6,229	71.0%	71 min	1.41%	C
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1234 quarter by quarter

DL 1234 did not run the same all year. Its best quarter was Jul–Sep 2025 at 68.6% on time and its weakest Jan–Mar 2026 at 52.2%, a swing of 16 points on roughly 69 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 202571 flights68.6%
Oct–Dec 202590 flights64.4%
Jan–Mar 202669 flights52.2%
Apr–Jun 202646 flights65.2%

Scale runs 45% to 75%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1234 did best on Monday at 66.0% on time and worst on Sunday at 46.7%. Each day rests on about 39 flights, so a gap of 19 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1234 runs late

One category carries most of the weight here. Carrier accounts for 63% of the 6,461 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
63%
Late-arriving aircraft
17%
National Airspace System
14%
Extreme weather
6%

The largest share of delay minutes, 63%, 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 4,080 of the 6,461 delay minutes reported here. The split is drawn from 6,461 delay minutes reported on DL 1234.

Cancellations are rare at 0.36%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and routes

What a delay on this flight costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 12.4% 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.

The 594 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

Every one of the 276 flights under DL 1234 in the data flew ATL to MIA. 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. 276 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 1234

For a booking, DL 1234 is a flight to put a long connection behind. 12.4% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.

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