Carrier route record
NKFLL→IAH
Spirit Airlines · Fort Lauderdale to Houston
- Flights
- 859
- Period
- July 2025 to June 2026
- Share of route
- 31%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Spirit Airlines.
Spirit on FLL to IAH sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 859 flights, with a median arrival 7 minutes early.
The national on-time rate over the same period is 77.6%, so Spirit on FLL to IAH runs 5 points behind the country as a whole. Across a thousand flights that is about 51 extra late arrivals.
Key figures
On time
72.5%
Arrivals under 15 minutes late, of 843 completed flights
Avg delay
75 min
Across delayed arrivals only, not all flights
Cancelled
1.75%
National rate is 1.81%
Whole route
82.1%
Every carrier on FLL to IAH, 2,755 flights
These figures cover 859 flights between July 2025 and June 2026. Beyond the headline rate, 11.4% 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 FLL to IAH
Spirit flew 859 of the 2,755 flights on FLL to IAH, about 31% of it. Its 72.5% on time is 10 points worse than the route as a whole, which runs 82.1%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from United at 88.3% to Frontier at 52.0%. One 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,792 | 88.3% | 84 min | 0.78% | A+ |
| Spirit Airlines (this page) | 859 | 72.5% | 75 min | 1.75% | C |
| Frontier Airlinesthin sample | 104 | 52.0% | 75 min | 1.92% | F |
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 33 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–8am212 flights90.0%
- 8am–11am19 flights—
- 11am–2pm23 flights—
- 2pm–5pm132 flights63.6%
- 5pm–8pm157 flights57.1%
- 8pm–5am316 flights70.6%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 57.1% on time, against 90.0% 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 8pm–5am window is the busiest, with 316 flights scheduled in it.
Across the year
Spirit on FLL to IAH through the year
November is the best month on the calendar at 86.4% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. March was the busiest month here, with 94 flights.
Across the week, Tuesday is the strongest day at 84.4% on time and Sunday the weakest at 57.1%. 27 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. Carrier accounts for 46% of the 17,000 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.
- 46%Carrier
- 30%National Airspace System
- 21%Late-arriving aircraft
- 4%Extreme weather
- 0%Security
The largest share of delay minutes, 46%, 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 7,937 of the 17,000 delay minutes reported here. The split is drawn from 17,359 reported delay minutes.
Cancellations sit at 1.75% against a national 1.81%, which is ordinary. Diversions add another 0.12%.
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. 11.4% 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 966 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 71.6% on time across 864 flights, within about 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. 859 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 FLL to IAH
Put together: treat all of this as provisional. 859 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 72.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 843 completed flights over 12 months sit behind that.
Related
Where to go next
- FLL to IAH, every carrier
- Spirit on IAH to FLL, the return leg
- United Airlines on FLL to IAH88.3%
- Frontier Airlines on FLL to IAH52.0%
- Spirit Airlines network-wide record
- Fort Lauderdale-Hollywood International (FLL) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- How often a connection fails at the major US hubs
- The best time of day to fly, according to 7.04 million flight records
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.