Carrier route record

NKMIA→ORD

Spirit Airlines · Miami to Chicago

Flights: 346
Period: July 2025 to June 2026
Share of route: 8%
Carriers: 4

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

Spirit on MIA to ORD 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 346 flights. The strongest carrier on the route with a full sample, American Airlines, flew 3,015 at 71.6% on time.

The national on-time rate over the same period is 77.6%, so Spirit on MIA to ORD runs 14 points behind the country as a whole. Across a thousand flights that is about 144 extra late arrivals.

On time

63.2%

Arrivals under 15 minutes late, of 321 completed flights

Avg delay

70 min

Across delayed arrivals only, not all flights

Cancelled

6.07%

National rate is 1.81%

Whole route

70.8%

Every carrier on MIA to ORD, 4,447 flights

These figures cover 346 flights between July 2025 and June 2026. Beyond the headline rate, 12.8% 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 ORD

Spirit flew 346 of the 4,447 flights on MIA to ORD, about 8% of it. Its 63.2% on time is 8 points worse than the route as a whole, which runs 70.8%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from Frontier at 73.3% to Spirit at 63.2%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The two carriers here are closely matched: about a point 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.

On-time performance by carrier on MIA to ORD
Airline	Flights	On time	Avg delay	Cancelled	Grade
Frontier Airlinesthin sample	46	73.3%	175 min	2.17%	C
American Airlines	3,015	71.6%	71 min	1.86%	C
United Airlines	1,040	70.7%	85 min	0.87%	C+
Spirit Airlines (this page)thin sample	346	63.2%	70 min	6.07%	D−

No carrier stands out. American tops the table at 71.6%, about a point clear of the bottom, which is inside the range this kind of sample moves year to year.

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

5am–8am174 flights77.4%
8am–11am24 flights—
11am–2pm37 flights75.0%
2pm–5pm105 flights31.5%
5pm–8pm6 flights—
8pm–5am—

Scale runs 25% to 85%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 77.4% of the time, against 31.5% for the afternoon window. That is 46 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 174 flights scheduled in it.

Across the year

Spirit on MIA to ORD through the year

Jul–Sep 202589 flights82.6%
Oct–Dec 202572 flights80.6%
Jan–Mar 2026146 flights47.0%
Apr–Jun 202639 flights44.4%

Scale runs 35% to 90%. 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 63.2% on time across 346 flights.

Spirit on MIA to ORD did not run the same all year. Its best quarter was Jul–Sep 2025 at 82.6% on time and its weakest Apr–Jun 2026 at 44.4%, a swing of 38 points on roughly 87 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, Thursday is the strongest day at 73.6% on time and Monday the weakest at 52.0%. 22 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Spirit runs late on this route

One category carries most of the weight here. National Airspace System accounts for 51% of the 8,247 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.

National Airspace System
51%
Carrier
36%
Late-arriving aircraft
13%
Extreme weather
0%
Security
0%

The largest share of delay minutes, 36%, 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 2,984 of the 8,247 delay minutes reported here. The split is drawn from 8,247 reported delay minutes.

51% 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 4,184 minutes out of 8,247, against a national NAS share of 21%.

Cancellations run at 6.07%, against 1.81% nationally. That is roughly one flight in fifteen 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. 12.8% 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 1,197 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 61.3% on time across 348 flights, within 2 points 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. 346 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 ORD

Put together: the delay figures matter less here than the 6.07% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 321 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