Carrier route record
DLMIA→ATL
Delta Air Lines · Miami to Atlanta
- Flights
- 3,300
- Period
- July 2025 to June 2026
- Share of route
- 53%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on MIA to ATL 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 an hour and a half on average. That is a workable record, not a spotless one. That rests on 3,300 flights. The strongest carrier on the route with a full sample, Frontier Airlines, flew 861 at 71.8% on time.
The US average over the same twelve months is 77.6%, so there is little to separate Delta on MIA to ATL from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
76.7%
Arrivals under 15 minutes late, of 3,249 completed flights
Avg delay
83 min
Across delayed arrivals only, not all flights
Cancelled
1.39%
National rate is 1.81%
Whole route
73.7%
Every carrier on MIA to ATL, 6,223 flights
These figures cover 3,300 flights between July 2025 and June 2026. Beyond the headline rate, 9.0% 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 MIA to ATL
Delta flew 3,300 of the 6,223 flights on MIA to ATL, most of the route. Its 76.7% on time is 3 points better than the route as a whole, which runs 73.7%. Ranked by on-time rate it is number two of six carriers on the route, where the range runs from Envoy at 78.3% to Republic at 65.9%. Three of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two carriers here are closely matched: 4 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 225 | 78.3% | 47 min | 1.33% | B |
| Delta Air Lines (this page) | 3,300 | 76.7% | 83 min | 1.39% | B |
| Spirit Airlinesthin sample | 269 | 74.4% | 71 min | 4.09% | C− |
| Frontier Airlines | 861 | 71.8% | 79 min | 1.86% | C |
| American Airlines | 1,524 | 67.5% | 82 min | 0.79% | C+ |
| Republic Airwaysthin sample | 44 | 65.9% | 60 min | 0.00% | C+ |
No carrier stands out. Frontier tops the table at 71.8%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Delta flight numbers on MIA to ATL
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 37 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am713 flights93.9%
- 8am–11am667 flights87.2%
- 11am–2pm508 flights78.6%
- 2pm–5pm712 flights67.2%
- 5pm–8pm657 flights57.5%
- 8pm–5am43 flights57.1%
Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 57.1% on time, against 93.9% 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 713 flights scheduled in it.
Across the year
Delta on MIA to ATL through the year
July is the worst month at 64.9% on time, 21 points below June, the best at 85.9%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. December was the busiest month here, with 306 flights.
Across the week, Wednesday is the strongest day at 82.7% on time and Sunday the weakest at 67.1%. 16 points is a smaller lever than departure hour, but it is free.
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 62,000 reported delay minutes.
- 40%Late-arriving aircraft
- 37%Carrier
- 19%National Airspace System
- 4%Extreme weather
- 0%Security
40% 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 62,000 reported delay minutes here, that single category outweighs weather by 9 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 62,459 reported delay minutes.
The largest share of delay minutes, 37%, 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 23,000 of the 62,000 delay minutes reported here.
Cancellations sit at 1.39% against a national 1.81%, which is ordinary. Diversions add another 0.15%.
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. 9.0% 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.
The return leg is a different operation and performs like one: it runs 70.3% on time across 3,298 flights, 6 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 6 points of difference.
The sample behind these figures is 3,300 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking Delta on MIA to ATL
Put together: the calendar is the biggest lever here, not the carrier or the hour. June runs 85.9% on time and July 64.9%, a swing of 21 points. If the dates move at all, move them out of July before you think about anything else. 3,249 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to ATL, every carrier
- Delta on ATL to MIA, the return leg
- Envoy Air on MIA to ATL78.3%
- Spirit Airlines on MIA to ATL74.4%
- Frontier Airlines on MIA to ATL71.8%
- American Airlines on MIA to ATL67.5%
- Delta Air Lines network-wide record
- Miami International (MIA) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.