Carrier route record
F9MIA→IAH
Frontier Airlines · Miami to Houston
- Flights
- 155
- 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 MIA to IAH lands a B, about a point better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That is a workable record, not a spotless one. That rests on 155 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,479 at 85.9% on time.
United Airlines is the most reliable of the three carriers covered here at 85.9% on time across 1,479 flights.
Key figures
On time
78.4%
Arrivals under 15 minutes late, of 153 completed flights
Avg delay
97 min
Across delayed arrivals only, not all flights
Cancelled
1.29%
National rate is 1.81%
Whole route
77.2%
Every carrier on MIA to IAH, 3,737 flights
These figures cover 155 flights between July 2025 and June 2026. Beyond the headline rate, 11.1% 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
Frontier against every carrier on MIA to IAH
Frontier flew 155 of the 3,737 flights on MIA to IAH, about 4% of it. Its 78.4% on time is about level with the route as a whole at 77.2%. Ranked by on-time rate it is number three of six carriers on the route, where the range runs from Envoy at 86.9% 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 85.9% of the time; Spirit Airlines manages 69.7%. Sample sizes sit next to every figure, because a two-point gap across 440 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 122 | 86.9% | 39 min | 0.00% | A+ |
| United Airlines | 1,479 | 85.9% | 91 min | 0.61% | A+ |
| Frontier Airlines (this page)thin sample | 155 | 78.4% | 97 min | 1.29% | B |
| American Airlines | 1,527 | 70.1% | 72 min | 1.24% | C |
| Spirit Airlines | 440 | 69.7% | 87 min | 2.73% | C |
| Republic Airwaysthin sample | 14 | 64.3% | 133 min | 0.00% | D+ |
The spread between United and Spirit is 16 points, wide enough that it should decide the booking. On a hundred trips that is 16 more arrivals inside the on-time window.
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 155 flights.
- 5am–8am43 flights90.7%
- 8am–11am49 flights85.4%
- 11am–2pm24 flights—
- 2pm–5pm9 flights—
- 5pm–8pm24 flights—
- 8pm–5am6 flights—
Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.
The early departures do better, though not dramatically: 90.7% on time for the 5am–8am window against 85.4% for 8am–11am. Worth taking if the schedule allows, not worth an extra connection. The 8am–11am window is the busiest, with 49 flights scheduled in it.
Across the year
Frontier on MIA to IAH through the year
- Jul–Sep 202532 flights68.8%
- Oct–Dec 202532 flights90.3%
- Jan–Mar 202634 flights72.7%
- Apr–Jun 202657 flights80.7%
Scale runs 60% to 95%. 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 78.4% on time across 155 flights.
Frontier on MIA to IAH did not run the same all year. Its best quarter was Oct–Dec 2025 at 90.3% on time and its weakest Jul–Sep 2025 at 68.8%, a swing of 22 points on roughly 39 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, Thursday is the strongest day at 76.5% on time and Sunday the weakest at 70.3%. 6 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 47% of the 3,208 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.
- 47%Late-arriving aircraft
- 33%Carrier
- 18%National Airspace System
- 2%Extreme weather
47% 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 3,208 reported delay minutes here, that single category outweighs weather by 26 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 3,208 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 90.7% on time here.
Cancellations sit at 1.29% 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. 11.1% 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 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 68.9% on time across 154 flights, 10 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 10 points of difference.
One caution: this is a thin sample. 155 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 MIA to IAH
Put together: treat all of this as provisional. 155 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 78.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 153 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to IAH, every carrier
- Frontier on IAH to MIA, the return leg
- Envoy Air on MIA to IAH86.9%
- United Airlines on MIA to IAH85.9%
- American Airlines on MIA to IAH70.1%
- Spirit Airlines on MIA to IAH69.7%
- Frontier Airlines network-wide record
- Miami International (MIA) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
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.