Carrier performance at one airport
DL→MIA
Delta Air Lines at Miami International
- Departures
- 11,630
- Period
- June 2025 to May 2026
- Routes
- 12
- Rank here
- #4 of 9
Delta Air Lines at Miami sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.4%. The late ones land a little over an hour behind schedule. That rests on 11,630 flights, of which Envoy Air flew 13,572 at 82.7% on time.
Measured against the airport rather than the country, Delta Air Lines runs half a point behind the 73.4% weighted average across all carriers at MIA. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.
Key figures
On time
72.8%
11,352 completed departures
Avg delay
82 min
Across delayed flights only
Cancelled
2.10%
At MIA, this carrier only
Rank here
#4
Of 9 carriers clearing the floor at MIA
These figures cover 12,000 flights between June 2025 and May 2026. Beyond the headline rate, 10.6% 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.
Against the competition
Every carrier at MIA, ranked
The choice of carrier is not cosmetic here. Envoy Air arrives on time 82.7% of the time; Spirit Airlines manages 66.2%. Sample sizes sit next to every figure, because a two-point gap across 3,864 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 13,572 | 82.7% | 49 min | 0.95% | B+ |
| United Airlines | 6,812 | 77.8% | 84 min | 1.01% | B |
| Frontier Airlines | 4,250 | 74.3% | 86 min | 2.21% | C |
| Delta Air Lines (this page) | 11,630 | 72.8% | 82 min | 2.10% | C |
| Southwest Airlines | 5,287 | 72.6% | 60 min | 1.19% | C |
| American Airlines | 63,838 | 71.6% | 73 min | 1.69% | C |
| Alaska Airlines | 533 | 68.7% | 57 min | 1.50% | C |
| Republic Airways | 1,145 | 67.3% | 95 min | 1.31% | C |
| Spirit Airlines | 3,864 | 66.2% | 79 min | 4.35% | C− |
Spirit Airlines cancels 4.3% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Route by route
Where Delta Air Lines flies from MIA
Delta Air Lines operates 12 routes out of MIA with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| MIA to ATL · Atlanta | 3,313 | 75.1% | 89 min | 1.48% | B |
| MIA to LGA · New York | 1,915 | 70.4% | 72 min | 3.92% | C− |
| MIA to JFK · New York | 1,620 | 70.7% | 82 min | 3.27% | C− |
| MIA to DTW · Detroit | 992 | 77.7% | 77 min | 0.91% | B+ |
| MIA to BOS · Boston | 886 | 69.0% | 82 min | 2.93% | C |
| MIA to MSP · Minneapolis | 759 | 77.1% | 75 min | 0.79% | B+ |
| MIA to LAX · Los Angeles | 493 | 80.0% | 79 min | 1.22% | B |
| MIA to SEA · Seattle | 365 | 61.3% | 92 min | 1.64% | D |
| MIA to DCA · Washingtonthin sample | 364 | 74.7% | 73 min | 0.82% | C+ |
| MIA to SLC · Salt Lake Citythin sample | 364 | 73.5% | 59 min | 0.55% | C+ |
| MIA to RDU · Raleighthin sample | 360 | 63.5% | 97 min | 1.94% | D |
| MIA to AUS · Austinthin sample | 192 | 66.8% | 97 min | 1.04% | C |
Departure window
Best time of day for this operation
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 33 points, against 17 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am2,123 flights89.5%
- 8am–11am1,353 flights85.9%
- 11am–2pm2,444 flights74.4%
- 2pm–5pm1,878 flights68.6%
- 5pm–8pm3,014 flights60.9%
- 8pm–5am818 flights56.4%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 56.4% on time, against 89.5% 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.
Across the year
Seasonal pattern
July is the worst month at 64.2% on time, 17 points below September, the best at 81.2%. 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.
Delay causes
What holds this operation up
- 39%Late-arriving aircraft
- 37%Carrier
- 20%National Airspace System
- 4%Extreme weather
- 0%Security
39% 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 252,000 reported delay minutes here, that single category outweighs weather by 11 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.
Cancellations sit at 2.10% against a national 1.80%, which is ordinary. Diversions add another 0.29%.
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.6% of arrivals land a full hour or more behind schedule, against 8.2% 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 sample behind these figures is 11,630 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.
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 81.2% on time and July 64.2%, a swing of 17 points. If the dates move at all, move them out of July before you think about anything else.
Common questions
Delta Air Lines at MIA
How often is Delta Air Lines at MIA delayed?
Roughly one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 27.2% of the 11,630 flights in this analysis, against 22.6% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on Delta Air Lines at MIA?
Envoy Air leads at 82.7% on time across 13,572 flights. Spirit Airlines is at the other end on 66.2%, a gap of 17 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on Delta Air Lines at MIA?
The 5am–8am departure window is the strongest at 89.5% on time. The 8pm–5am window is the weakest at 56.4%, 33 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on Delta Air Lines at MIA?
July is the weakest month at 64.2% on time, compared with 81.2% in September. Across the year that is 17 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.