Carrier route record

DLDTW→MIA

Delta Air Lines · Detroit to Miami

Flights: 965
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 DTW to MIA lands a B+, about a point better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 55 minutes on average. That is a workable record, not a spotless one. That rests on 965 flights, with a median arrival 4 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on DTW to MIA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

78.4%

Arrivals under 15 minutes late, of 953 completed flights

Avg delay

55 min

Across delayed arrivals only, not all flights

Cancelled

0.93%

National rate is 1.81%

Whole route

80.5%

Every carrier on DTW to MIA, 1,815 flights

These figures cover 965 flights between July 2025 and June 2026. The median arrival is 4 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Delta against every carrier on DTW to MIA

Delta flew 965 of the 1,815 flights on DTW to MIA, most of the route. Its 78.4% on time is 2 points worse than the route as a whole, which runs 80.5%. Ranked by on-time rate it is number four of six carriers on the route, where the range runs from American at 89.4% to Frontier at 66.7%. Four of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on DTW to MIA
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlines	394	89.4%	102 min	1.27%	A
Envoy Airthin sample	87	79.3%	67 min	0.00%	B+
Spirit Airlinesthin sample	295	79.3%	66 min	3.39%	B−
Delta Air Lines (this page)	965	78.4%	55 min	0.93%	B+
Republic Airwaysthin sample	10	70.0%	30 min	0.00%	C+
Frontier Airlinesthin sample	64	66.7%	96 min	1.56%	C

Flight by flight

Delta flight numbers on DTW to MIA

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 38 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am154 flights79.1%
8am–11am210 flights89.3%
11am–2pm82 flights73.2%
2pm–5pm218 flights77.4%
5pm–8pm256 flights76.5%
8pm–5am45 flights51.1%

Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 51.1% on time, against 89.3% for the 8am–11am 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 256 flights scheduled in it.

Across the year

Delta on DTW to MIA through the year

Darker means more delays. Figures are on-time percentages.February best, December worst

December is the weak month at 58.4% on time, against 89.2% in February. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. January was the busiest month here, with 93 flights.

Across the week, Tuesday is the strongest day at 89.1% on time and Sunday the weakest at 67.2%. 22 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 52% of the 11,000 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.

Carrier
52%
National Airspace System
36%
Late-arriving aircraft
10%
Extreme weather
1%

36% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 4,048 minutes out of 11,000, against a national NAS share of 21%. The split is drawn from 11,316 reported delay minutes.

The largest share of delay minutes, 52%, 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 5,928 of the 11,000 delay minutes reported here.

Cancellations sit at 0.93% against a national 1.81%, which is ordinary. Diversions add another 0.31%.

Connections and stage length

What a delay here costs

7.2% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 55 minutes, which a normal layover absorbs.

The 1,145 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 runs 77.7% on time across 966 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 965 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 Delta on DTW to MIA

Put together: treat all of this as provisional. 965 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 78.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 953 completed flights over 12 months sit behind that.

Where to go next

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