Carrier route record
NKATL→IAH
Spirit Airlines · Atlanta to Houston
- Flights
- 384
- Period
- July 2025 to June 2026
- Share of route
- 8%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Spirit Airlines.
Spirit on ATL to IAH draws a C−. About one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 384 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,255 at 85.1% on time.
United Airlines is the most reliable of the three carriers covered here at 85.1% on time across 1,255 flights.
Key figures
On time
66.3%
Arrivals under 15 minutes late, of 365 completed flights
Avg delay
76 min
Across delayed arrivals only, not all flights
Cancelled
4.69%
National rate is 1.81%
Whole route
76.4%
Every carrier on ATL to IAH, 4,914 flights
These figures cover 384 flights between July 2025 and June 2026. Beyond the headline rate, 15.3% 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 ATL to IAH
Spirit flew 384 of the 4,914 flights on ATL to IAH, about 8% of it. Its 66.3% on time is 10 points worse than the route as a whole, which runs 76.4%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from United at 85.1% to Spirit at 66.3%.
The choice of carrier is not cosmetic here. United Airlines arrives on time 85.1% of the time; Frontier Airlines manages 68.9%. Sample sizes sit next to every figure, because a two-point gap across 767 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,255 | 85.1% | 78 min | 1.12% | A |
| Delta Air Lines | 2,508 | 75.9% | 55 min | 1.95% | B |
| Frontier Airlines | 767 | 68.9% | 82 min | 1.43% | C |
| Spirit Airlines (this page) | 384 | 66.3% | 76 min | 4.69% | C− |
The spread between United and Frontier 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 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 25 points, against 16 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am74 flights81.9%
- 8am–11am89 flights57.1%
- 11am–2pm5 flights—
- 2pm–5pm50 flights74.0%
- 5pm–8pm38 flights62.2%
- 8pm–5am128 flights60.5%
Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 81.9% of the time, against 57.1% for the morning window. That is 25 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 128 flights scheduled in it.
Across the year
Spirit on ATL to IAH through the year
November is the best month on the calendar at 87.8% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. January was the busiest month here, with 49 flights.
Across the week, Wednesday is the strongest day at 74.5% on time and Sunday the weakest at 53.2%. 21 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. Late-arriving aircraft accounts for 48% of the 9,401 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.
- 48%Late-arriving aircraft
- 26%National Airspace System
- 25%Carrier
- 0%Extreme weather
48% 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 9,401 reported delay minutes here, that single category outweighs weather by 48 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 9,401 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 81.9% on time here.
Cancellations run at 4.69%, 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. 15.3% 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 689 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 77.4% on time across 375 flights, 11 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 11 points of difference.
One caution: this is a thin sample. 384 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 ATL to IAH
Put together: the delay figures matter less here than the 4.69% cancellation rate. A late arrival costs you a little over an hour; 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. 365 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to IAH, every carrier
- Spirit on IAH to ATL, the return leg
- United Airlines on ATL to IAH85.1%
- Delta Air Lines on ATL to IAH75.9%
- Frontier Airlines on ATL to IAH68.9%
- Spirit Airlines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
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.