Carrier route record

NKSJU→MIA

Spirit Airlines · San Juan to Miami

Flights: 184
Period: July 2025 to June 2026
Share of route: 7%
Carriers: 3

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

Spirit on SJU to MIA sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 184 flights. The strongest carrier on the route with a full sample, American Airlines, flew 2,079 at 78.5% on time.

The national on-time rate over the same period is 77.6%, so Spirit on SJU to MIA runs 7 points behind the country as a whole. Across a thousand flights that is about 65 extra late arrivals.

On time

71.1%

Arrivals under 15 minutes late, of 180 completed flights

Avg delay

94 min

Across delayed arrivals only, not all flights

Cancelled

2.17%

National rate is 1.81%

Whole route

77.7%

Every carrier on SJU to MIA, 2,642 flights

These figures cover 184 flights between July 2025 and June 2026. Beyond the headline rate, 11.7% 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 SJU to MIA

Spirit flew 184 of the 2,642 flights on SJU to MIA, about 7% of it. Its 71.1% on time is 7 points worse than the route as a whole, which runs 77.7%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from American at 78.5% to Spirit at 71.1%.

The two carriers here are closely matched: 2 points 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 SJU to MIA
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlines	2,079	78.5%	93 min	0.63%	B+
Frontier Airlines	379	76.5%	95 min	2.11%	B
Spirit Airlines (this page)thin sample	184	71.1%	94 min	2.17%	C

No carrier stands out. American tops the table at 78.5%, 2 points 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 is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 184 flights.

There are not enough flights in each departure window to split Spirit's SJU to MIA record by time of day without the percentages moving on noise. The headline rate of 71.1% is the reliable figure here.

Across the year

Spirit on SJU to MIA through the year

Jul–Sep 202557 flights64.9%
Oct–Dec 202536 flights65.7%
Jan–Mar 202665 flights77.4%
Apr–Jun 202626 flights—

Scale runs 55% to 85%. 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 71.1% on time across 184 flights.

Spirit on SJU to MIA did not run the same all year. Its best quarter was Jan–Mar 2026 at 77.4% on time and its weakest Jul–Sep 2025 at 64.9%, a swing of 13 points on roughly 61 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, Friday is the strongest day at 80.0% on time and Monday the weakest at 66.7%. 13 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. Late-arriving aircraft accounts for 55% of the 4,896 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.

Late-arriving aircraft
55%
National Airspace System
23%
Carrier
22%

55% 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 4,896 reported delay minutes here, that single category outweighs weather by 55 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 4,896 reported delay minutes.

Cancellations sit at 2.17% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

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. 11.7% 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 1,045 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 55.8% on time across 179 flights, 15 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 15 points of difference.

One caution: this is a thin sample. 184 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 SJU to MIA

Put together: treat all of this as provisional. 184 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 71.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 180 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