Carrier route record
F9MIA→ATL
Frontier Airlines · Miami to Atlanta
- Flights
- 861
- Period
- July 2025 to June 2026
- Share of route
- 14%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.
Frontier on MIA to ATL sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 861 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 3,300 at 76.7% on time.
The national on-time rate over the same period is 77.6%, so Frontier on MIA to ATL runs 6 points behind the country as a whole. Across a thousand flights that is about 58 extra late arrivals.
Key figures
On time
71.8%
Arrivals under 15 minutes late, of 844 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
1.86%
National rate is 1.81%
Whole route
73.7%
Every carrier on MIA to ATL, 6,223 flights
These figures cover 861 flights between July 2025 and June 2026. Beyond the headline rate, 11.3% 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
Frontier against every carrier on MIA to ATL
Frontier flew 861 of the 6,223 flights on MIA to ATL, about 14% of it. Its 71.8% on time is 2 points worse than the route as a whole, which runs 73.7%. Ranked by on-time rate it is number four 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 choice of carrier is not cosmetic here. Delta Air Lines arrives on time 76.7% of the time; American Airlines manages 67.5%. Sample sizes sit next to every figure, because a two-point gap across 1,524 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 225 | 78.3% | 47 min | 1.33% | B |
| Delta Air Lines | 3,300 | 76.7% | 83 min | 1.39% | B |
| Spirit Airlinesthin sample | 269 | 74.4% | 71 min | 4.09% | C− |
| Frontier Airlines (this page) | 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+ |
Delta leads American by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Frontier flight numbers on MIA to ATL
Departure window
When Frontier runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 30 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am229 flights88.4%
- 8am–11am83 flights75.3%
- 11am–2pm137 flights72.8%
- 2pm–5pm71 flights75.7%
- 5pm–8pm314 flights58.6%
- 8pm–5am27 flights—
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 58.6% on time, against 88.4% 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 5pm–8pm window is the busiest, with 314 flights scheduled in it.
Across the year
Frontier on MIA to ATL through the year
October is the best month on the calendar at 83.3% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. May was the busiest month here, with 93 flights.
Across the week, Wednesday is the strongest day at 81.2% on time and Saturday the weakest at 65.3%. 16 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Frontier runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 44% of the 19,000 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.
- 44%Late-arriving aircraft
- 30%National Airspace System
- 25%Carrier
- 1%Extreme weather
44% 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 19,000 reported delay minutes here, that single category outweighs weather by 35 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 18,879 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 88.4% on time here.
Cancellations sit at 1.86% against a national 1.81%, which is ordinary. Diversions add another 0.12%.
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. 11.3% 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 65.3% on time across 864 flights, 7 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 7 points of difference.
One caution: this is a thin sample. 861 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 Frontier on MIA to ATL
Put together: treat all of this as provisional. 861 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 71.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 844 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to ATL, every carrier
- Frontier on ATL to MIA, the return leg
- Envoy Air on MIA to ATL78.3%
- Delta Air Lines on MIA to ATL76.7%
- Spirit Airlines on MIA to ATL74.4%
- American Airlines on MIA to ATL67.5%
- Frontier Airlines 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
- How often a connection fails at the major US hubs
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.