Route reliability record
IAH→FLL
Houston to Fort Lauderdale
- Flights
- 2,760
- Period
- July 2025 to June 2026
- Distance
- 966 mi
- Carriers
- 3
This route lands a B, 2 points better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 2,760 flights, of which United Airlines flew 1,792 at 85.0% on time.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.8%
Arrivals under 15 minutes late, of 2,724 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
1.20%
National rate is 1.81%
Best carrier
United
85.0% on time across 1,792 flights
These figures cover 2,760 flights between July 2025 and June 2026. The median arrival is 8 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Which airline is most reliable on IAH to FLL
The choice of carrier is not cosmetic here. United Airlines arrives on time 85.0% of the time; Spirit Airlines manages 71.6%. Sample sizes sit next to every figure, because a two-point gap across 864 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,792 | 85.0% | 64 min | 0.73% | A+ |
| Spirit Airlines | 864 | 71.6% | 73 min | 1.85% | C |
| Frontier Airlinesthin sample | 104 | 59.0% | 48 min | 3.85% | D− |
The spread between United and Spirit is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 more arrivals inside the on-time window.
Departure window
The best time of day to leave
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 2,760 flights.
- 5am–8am629 flights83.3%
- 8am–11am554 flights79.8%
- 11am–2pm345 flights84.2%
- 2pm–5pm640 flights79.0%
- 5pm–8pm565 flights74.7%
- 8pm–5am27 flights—
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 84.2% on time, ahead of 5pm–8pm at 74.7%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 2pm–5pm window is the busiest, with 640 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 24 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
September is the best month on the calendar at 89.3% 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 293 flights.
Across the week, Tuesday is the strongest day at 87.9% on time and Sunday the weakest at 72.8%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 36,000 reported delay minutes.
- 34%Carrier
- 32%National Airspace System
- 29%Late-arriving aircraft
- 5%Extreme weather
- 0%Security
No single cause dominates. carrier at 34%, national airspace system at 32% and late-arriving aircraft at 29% split the 36,000 reported delay minutes between them. An even spread like this usually means the operation is running close to its designed capacity with no one obvious weak point, and it is the hardest pattern for a traveller to route around. The split is drawn from 36,479 reported delay minutes.
Cancellations sit at 1.20% against a national 1.81%, which is ordinary. Diversions add another 0.11%.
Connections and stage length
What a delay here actually costs
7.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the about an hour kind, which a normal layover absorbs.
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 82.1% on time across 2,755 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.
The sample behind these figures is 2,760 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 89.3% on time and March 65.7%, a swing of 24 points. If the dates move at all, move them out of March before you think about anything else. 2,724 completed flights over 12 months sit behind that.
Common questions
IAH to FLL questions
How often is IAH to FLL delayed?
About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.2% of the 2,760 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on IAH to FLL?
United Airlines leads at 85.0% on time across 1,792 flights. Spirit Airlines is at the other end on 71.6%, a gap of 13 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on IAH to FLL?
The 11am–2pm departure window is the strongest at 84.2% on time. The 5pm–8pm window is the weakest at 74.7%, 10 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are March delays on IAH to FLL?
March is the weakest month at 65.7% on time, compared with 89.3% in September. Across the year that is 24 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- FLL to IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Fort Lauderdale-Hollywood International (FLL) delay statistics
- United Airlines on-time record85.0%
- Spirit Airlines on-time record71.6%
- Frontier Airlines on-time record59.0%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. IAH to FLL and FLL to IAH are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.