Carrier route record
F9IAH→MIA
Frontier Airlines · Houston to Miami
- Flights
- 154
- Period
- July 2025 to June 2026
- Share of route
- 4%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.
Frontier on IAH 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, 9 points worse than the national rate of 77.6%. The late ones land about 2.4 hours behind schedule. That rests on 154 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,479 at 80.3% on time.
United Airlines is the most reliable of the three carriers covered here at 80.3% on time across 1,479 flights.
Key figures
On time
68.9%
Arrivals under 15 minutes late, of 151 completed flights
Avg delay
142 min
Across delayed arrivals only, not all flights
Cancelled
1.95%
National rate is 1.81%
Whole route
77.8%
Every carrier on IAH to MIA, 3,736 flights
These figures cover 154 flights between July 2025 and June 2026. Beyond the headline rate, 14.6% 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
Frontier against every carrier on IAH to MIA
Frontier flew 154 of the 3,736 flights on IAH to MIA, about 4% of it. Its 68.9% on time is 9 points worse than the route as a whole, which runs 77.8%. Ranked by on-time rate it is number five of six carriers on the route, where the range runs from United at 80.3% to Republic at 64.3%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. United Airlines arrives on time 80.3% of the time; Spirit Airlines manages 70.7%. Sample sizes sit next to every figure, because a two-point gap across 441 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,479 | 80.3% | 61 min | 0.41% | B+ |
| Envoy Airthin sample | 122 | 78.5% | 52 min | 0.00% | B+ |
| American Airlines | 1,526 | 78.3% | 111 min | 1.31% | B |
| Spirit Airlines | 441 | 70.7% | 79 min | 3.17% | C− |
| Frontier Airlines (this page)thin sample | 154 | 68.9% | 142 min | 1.95% | C |
| Republic Airwaysthin sample | 14 | 64.3% | 173 min | 0.00% | D+ |
Spirit Airlines 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 Frontier 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 154 flights.
There are not enough flights in each departure window to split Frontier's IAH to MIA record by time of day without the percentages moving on noise. The headline rate of 68.9% is the reliable figure here.
Across the year
Frontier on IAH to MIA through the year
- Jul–Sep 202532 flights68.8%
- Oct–Dec 202532 flights71.0%
- Jan–Mar 202634 flights73.5%
- Apr–Jun 202656 flights64.8%
Scale runs 55% to 80%. 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 68.9% on time across 154 flights.
Quarter by quarter Frontier on IAH to MIA held fairly steady: 68.8% in Jul–Sep 2025, 71.0% in Oct–Dec 2025, 73.5% in Jan–Mar 2026 and 64.8% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
Across the week, Thursday is the strongest day at 73.5% on time and Saturday the weakest at 53.3%. 20 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Frontier runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 49% of the 6,695 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.
- 49%Late-arriving aircraft
- 42%Carrier
- 7%National Airspace System
- 1%Extreme weather
49% 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 6,695 reported delay minutes here, that single category outweighs weather by 36 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 6,695 reported delay minutes.
The largest share of delay minutes, 42%, 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 2,804 of the 6,695 delay minutes reported here.
Cancellations sit at 1.95% 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. 14.6% 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 964 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 78.4% on time across 155 flights, 10 points above 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 10 points of difference.
One caution: this is a thin sample. 154 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 Frontier on IAH to MIA
Put together: treat all of this as provisional. 154 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 68.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 151 completed flights over 12 months sit behind that.
Related
Where to go next
- IAH to MIA, every carrier
- Frontier on MIA to IAH, the return leg
- United Airlines on IAH to MIA80.3%
- Envoy Air on IAH to MIA78.5%
- American Airlines on IAH to MIA78.3%
- Spirit Airlines on IAH to MIA70.7%
- Frontier Airlines network-wide record
- George Bush Intercontinental (IAH) delay statistics
- Miami International (MIA) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.