Flight number record
DL 1234
Delta Air Lines · Atlanta to Miami
- Route
- ATL → MIA
- Departs
- 22:30
- Flights
- 274
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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 274 flights, with a median arrival 6 minutes late.
The national on-time rate over the same period is 77.3%, so DL 1234 runs 16 points behind the country as a whole. Across a thousand flights that is about 159 extra late arrivals.
Key figures
On time
61.4%
Arrivals under 15 minutes late, of 272 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
0.73%
National rate is 1.89%
1 hour+ late
13.2%
National rate is 8.3%
These figures cover 274 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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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 35 of 274 flights, with 20:30 (34 flights) and 22:38 (33 flights) next.
- Departs 22:3035 flights12.8%
- Departs 20:3034 flights12.4%
- Departs 22:3833 flights12.0%
Scale runs 0% to 100%.
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 70.1%, and DL 1234 runs 9 points worse at 61.4%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
DL 1234 next to ATL to MIA
Every carrier on ATL to MIA combined arrived on time 71.2% of the time across 6,280 flights, so DL 1234 is 10 points behind it. Delta flew 3,321 flights on the same city pair under all its flight numbers, including this one, and those ran 71.4% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 20 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1234thin sample | 274 | 61.4% | 61 min | 0.73% | D+ |
| All Delta Air Lines on ATL–MIA | 3,321 | 71.4% | 56 min | 1.81% | C |
| All carriers on ATL–MIA | 6,280 | 71.2% | 73 min | 1.61% | C |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | 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 86.7% on time and its weakest Jul–Sep 2026 at 45.9%, a swing of 41 points on roughly 55 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 202530 flights86.7%
- Oct–Dec 202590 flights64.4%
- Jan–Mar 202669 flights52.2%
- Apr–Jun 202646 flights65.2%
- Jul–Sep 202639 flights45.9%
Scale runs 35% to 90%.
By weekday, DL 1234 did best on Wednesday at 80.0% on time and worst on Friday at 50.0%. Each day rests on about 39 flights, so a gap of 30 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 1234 runs when it is late
The 105 late arrivals split 39 under half an hour, 30 between 30 and 60 minutes, and 36 an hour or more.
- 15+ min early36 flights13.2%
- Within 15 min131 flights48.2%
- 15–29 min late39 flights14.3%
- 30–59 min late30 flights11.0%
- 1–2 hours late26 flights9.6%
- 2+ hours late10 flights3.7%
Scale runs 0% to 100%.
Share of 272 completed flights by arrival against schedule.
18 of 111 late departures made up the time and arrived on time, 16% of them. 12 flights left on time and still arrived late.
The worst days
Worst days for DL 1234
The latest arrival of the period was on 10 October 2025, 11 hours 7 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 10 October 2025 | 11 hours 7 minutes | Carrier |
| 6 March 2026 | 5 hours 35 minutes | Extreme weather |
| 19 July 2026 | 3 hours 38 minutes | Carrier |
| 29 November 2025 | 3 hours 6 minutes | Carrier |
| 5 January 2026 | 2 hours 45 minutes | Late-arriving aircraft |
Delay causes
Why DL 1234 runs late
Carrier accounts for 59% of the 6,389 delay minutes carriers reported here, and the remaining four split what is left.
- 59%Carrier
- 22%Late-arriving aircraft
- 14%National Airspace System
- 6%Extreme weather
The largest share of delay minutes, 59%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 3,753 of the 6,389 delay minutes reported here. The split is drawn from 6,389 delay minutes reported on DL 1234.
Cancellations are rare at 0.73%, below the national 1.89% 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
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.
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.
Every one of the 274 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. 274 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. 13.2% 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.
Related
Where to go next
- ATL to MIA, every carrier and departure
- MIA to ATL, the return direction
- Delta Air Lines 1510 on the same route83.7%
- Delta Air Lines 1332 on the same route82.2%
- Delta Air Lines 1588 on the same route64.2%
- Delta Air Lines 1323 on the same route62.4%
- Delta Air Lines 1579 on the same route75.3%
- Frontier Airlines 4406 on the same route72.5%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Miami International (MIA) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- How often a connection fails at the major US hubs
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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.