Route reliability record
IAH→SLC
Houston to Salt Lake City
- Flights
- 1,957
- Period
- July 2025 to June 2026
- Distance
- 1,195 mi
- Carriers
- 3
This route lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,957 IAH to SLC flights, of which United Airlines flew 879 at 82.9% on time.
Best time to fly IAH to SLC: a 8am–11am departure, ideally on a Saturday. Flights in that window arrived on time 86.6% of the time and Saturday flights 87.1%, against 82.6% for the route overall.
Set against the rest of the country, this route's record is 5 points better than the US average of 77.6%. That gap is worth roughly 50 fewer late arrivals for every thousand flights.
Key figures
On time
82.6%
Arrivals under 15 minutes late, of 1,942 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
0.51%
National rate is 1.81%
Best carrier
United
82.9% on time across 879 flights
These figures cover 1,957 flights between July 2025 and June 2026. The median arrival is 7 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 SLC
The two carriers here are closely matched: half a point separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 879 | 82.9% | 64 min | 0.68% | B+ |
| Delta Air Lines | 1,011 | 82.7% | 93 min | 0.30% | B+ |
| SkyWest Airlinesthin sample | 67 | 78.8% | 63 min | 1.49% | B |
No carrier stands out. United tops the table at 82.9%, half a point clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on IAH to SLC
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Best ways to make this trip
The most reliable ways to fly Houston to Salt Lake City
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. IAH → SLCHouston to Salt Lake City | Delta Air Lines | 82.5% | 82.7% | 0.30% | 2pm–5pm, Tue | DL 1583 07:40 |
| 2. IAH → SLCHouston to Salt Lake City | United Airlines | 82.3% | 82.9% | 0.68% | 11am–2pm, Sat | UA 2242 09:45 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 11 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–8am365 flights84.9%
- 8am–11am372 flights86.6%
- 11am–2pm422 flights85.4%
- 2pm–5pm116 flights86.1%
- 5pm–8pm294 flights78.4%
- 8pm–5am388 flights75.8%
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 86.6% of the time, against 75.8% for the overnight window. That is 11 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 422 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 14 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.
August is the worst month at 77.4% on time, 14 points below January, the best at 91.1%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. March was the busiest month here, with 211 flights.
Across the week, Saturday is the strongest day at 87.1% on time and Sunday the weakest at 78.5%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 46% of the 27,000 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
- 38%Late-arriving aircraft
- 12%National Airspace System
- 5%Extreme weather
38% 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 27,000 reported delay minutes here, that single category outweighs weather by 8 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 26,573 reported delay minutes.
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 12,000 of the 27,000 delay minutes reported here.
Cancellations are rare at 0.51%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
6.4% 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 last a little over an hour, which a normal layover absorbs.
The 1,195 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 84.7% on time across 1,957 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 1,957 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.
Work out the risk of missing a connection in SLC after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 91.1% on time and August 77.4%, a swing of 14 points. If the dates move at all, move them out of August before you think about anything else. 1,942 completed flights over 12 months sit behind that.
Common questions
IAH to SLC questions
How often is IAH to SLC delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.4% of the 1,957 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on IAH to SLC?
United Airlines leads at 82.9% on time across 879 flights. Delta Air Lines is at the other end on 82.7%, a gap of half a point. 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 SLC?
The 8am–11am departure window is the strongest at 86.6% on time. The 8pm–5am window is the weakest at 75.8%, 11 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 August delays on IAH to SLC?
August is the weakest month at 77.4% on time, compared with 91.1% in January. Across the year that is 14 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
- SLC to IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Salt Lake City International (SLC) delay statistics
- United Airlines on IAH to SLC82.9%
- Delta Air Lines on IAH to SLC82.7%
- IAH to ORD, a related route74.8%
- DEN to SLC, a related route77.5%
- IAH to DFW, a related route75.0%
- United Airlines on-time record82.9%
- Delta Air Lines on-time record82.7%
- SkyWest Airlines on-time record78.8%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. IAH to SLC and SLC to IAH are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.