Carrier route record

NKMIA→DTW

Spirit Airlines · Miami to Detroit

Flights: 292
Period: July 2025 to June 2026
Share of route: 16%
Carriers: 6

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Spirit Airlines.

Spirit on MIA to DTW draws a D−. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 292 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 966 at 77.7% on time.

The national on-time rate over the same period is 77.6%, so Spirit on MIA to DTW runs 16 points behind the country as a whole. Across a thousand flights that is about 159 extra late arrivals.

On time

61.7%

Arrivals under 15 minutes late, of 282 completed flights

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

3.42%

National rate is 1.81%

Whole route

72.9%

Every carrier on MIA to DTW, 1,813 flights

These figures cover 292 flights between July 2025 and June 2026. Beyond the headline rate, 15.6% 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.

Carrier by carrier

Spirit against every carrier on MIA to DTW

Spirit flew 292 of the 1,813 flights on MIA to DTW, about 16% of it. Its 61.7% on time is 11 points worse than the route as a whole, which runs 72.9%. Ranked by on-time rate it is number five of six carriers on the route, where the range runs from Envoy at 82.8% to Republic at 60.0%. 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 77.7% of the time; American Airlines manages 68.3%. Sample sizes sit next to every figure, because a two-point gap across 394 flights means less than a ten-point one.

On-time performance by carrier on MIA to DTW
Airline	Flights	On time	Avg delay	Cancelled	Grade
Envoy Airthin sample	87	82.8%	46 min	0.00%	B+
Delta Air Lines	966	77.7%	88 min	0.93%	B+
American Airlines	394	68.3%	66 min	1.27%	C
Frontier Airlinesthin sample	64	67.7%	88 min	3.12%	C−
Spirit Airlines (this page)thin sample	292	61.7%	71 min	3.42%	D−
Republic Airwaysthin sample	10	60.0%	162 min	0.00%	D+

Delta leads American by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When Spirit runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 25 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am9 flights—
8am–11am39 flights72.2%
11am–2pm31 flights74.2%
2pm–5pm33 flights54.5%
5pm–8pm127 flights62.4%
8pm–5am53 flights49.0%

Scale runs 40% to 80%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 49.0% on time, against 74.2% for the 11am–2pm 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 127 flights scheduled in it.

Across the year

Spirit on MIA to DTW through the year

Jul–Sep 202577 flights55.8%
Oct–Dec 202574 flights68.6%
Jan–Mar 2026114 flights59.6%
Apr–Jun 202627 flights—

Scale runs 45% to 75%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 61.7% on time across 292 flights.

Spirit on MIA to DTW did not run the same all year. Its best quarter was Oct–Dec 2025 at 68.6% on time and its weakest Jul–Sep 2025 at 55.8%, a swing of 13 points on roughly 97 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.

Across the week, Wednesday is the strongest day at 79.4% on time and Friday the weakest at 54.3%. 25 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Spirit 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 7,648 reported delay minutes.

National Airspace System
40%
Late-arriving aircraft
35%
Carrier
21%
Extreme weather
2%
Security
1%

35% 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 7,648 reported delay minutes here, that single category outweighs weather by 21 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 7,648 reported delay minutes.

40% 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 3,093 minutes out of 7,648, against a national NAS share of 21%.

Cancellations run at 3.42%, against 1.81% nationally. That is about one flight in 30 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

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. 15.6% 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 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 is a different operation and performs like one: it runs 79.3% on time across 295 flights, 18 points above 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 18 points of difference.

One caution: this is a thin sample. 292 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 Spirit on MIA to DTW

Put together: the delay figures matter less here than the 3.42% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 11am–2pm departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 282 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