Carrier route record
NKBOS→FLL
Spirit Airlines · Boston to Fort Lauderdale
- Flights
- 571
- Period
- July 2025 to June 2026
- Share of route
- 17%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Spirit Airlines.
Spirit on BOS to FLL draws a D−. About one flight in three arrives at least 15 minutes late, and the typical late arrival is an hour and a half behind schedule. Build slack into anything you connect to. That rests on 571 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 885 at 69.5% on time.
The national on-time rate over the same period is 77.6%, so Spirit on BOS to FLL runs 13 points behind the country as a whole. Across a thousand flights that is about 130 extra late arrivals.
Key figures
On time
64.6%
Arrivals under 15 minutes late, of 542 completed flights
Avg delay
82 min
Across delayed arrivals only, not all flights
Cancelled
5.08%
National rate is 1.81%
Whole route
66.7%
Every carrier on BOS to FLL, 3,417 flights
These figures cover 571 flights between July 2025 and June 2026. Beyond the headline rate, 16.1% 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 BOS to FLL
Spirit flew 571 of the 3,417 flights on BOS to FLL, about 17% of it. Its 64.6% on time is 2 points worse than the route as a whole, which runs 66.7%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Delta at 69.5% to Spirit at 64.6%.
The two carriers here are closely matched: 3 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 885 | 69.5% | 78 min | 3.05% | C− |
| JetBlue Airways | 1,961 | 66.1% | 69 min | 3.16% | C− |
| Spirit Airlines (this page) | 571 | 64.6% | 82 min | 5.08% | D− |
JetBlue Airways cancels 3.2% 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.
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 45 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am301 flights82.2%
- 8am–11am—
- 11am–2pm40 flights42.5%
- 2pm–5pm37 flights68.6%
- 5pm–8pm127 flights36.8%
- 8pm–5am66 flights47.6%
Scale runs 30% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 36.8% on time, against 82.2% 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. The 5am–8am window is the busiest, with 301 flights scheduled in it.
Across the year
Spirit on BOS to FLL through the year
October is the best month on the calendar at 83.1% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. February was the busiest month here, with 69 flights.
Across the week, Wednesday is the strongest day at 72.0% on time and Sunday the weakest at 55.4%. 17 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 44% of the 16,000 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.
- 44%National Airspace System
- 39%Carrier
- 14%Late-arriving aircraft
- 3%Extreme weather
- 0%Security
The largest share of delay minutes, 39%, 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 6,087 of the 16,000 delay minutes reported here. The split is drawn from 15,740 reported delay minutes.
44% 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 6,940 minutes out of 16,000, against a national NAS share of 21%.
Cancellations run at 5.08%, against 1.81% nationally. That is about one flight in twenty 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. 16.1% 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 1,237 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 61.7% on time across 570 flights, within 3 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. 571 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 BOS to FLL
Put together: the delay figures matter less here than the 5.08% cancellation rate. A late arrival costs you an hour and a half; 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. 542 completed flights over 12 months sit behind that.
Related
Where to go next
- BOS to FLL, every carrier
- Spirit on FLL to BOS, the return leg
- Delta Air Lines on BOS to FLL69.5%
- JetBlue Airways on BOS to FLL66.1%
- Spirit Airlines network-wide record
- Boston Logan International (BOS) delay statistics
- Fort Lauderdale-Hollywood International (FLL) delay statistics
- The US routes with the most cancellations
- What a cancellation rate actually tells you (and what it hides)
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.