Carrier route record

DLSLC→IAH

Delta Air Lines · Salt Lake City to Houston

Flights: 1,011
Period: July 2025 to June 2026
Share of route: 52%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on SLC to IAH 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 1,011 flights, with a median arrival 7 minutes early.

Set against the rest of the country, Delta's SLC to IAH record is 5 points better than the US average of 77.6%. That gap is worth roughly 45 fewer late arrivals for every thousand flights.

On time

82.1%

Arrivals under 15 minutes late, of 1,005 completed flights

Avg delay

81 min

Across delayed arrivals only, not all flights

Cancelled

0.20%

National rate is 1.81%

Whole route

84.7%

Every carrier on SLC to IAH, 1,957 flights

These figures cover 1,011 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

Delta against every carrier on SLC to IAH

Delta flew 1,011 of the 1,957 flights on SLC to IAH, most of the route. Its 82.1% on time is 3 points worse than the route as a whole, which runs 84.7%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from SkyWest at 87.9% to Delta at 82.1%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on SLC to IAH
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	68	87.9%	57 min	1.47%	A
United Airlines	878	87.5%	67 min	1.48%	A
Delta Air Lines (this page)	1,011	82.1%	81 min	0.20%	B+

Flight by flight

Delta flight numbers on SLC to IAH

Departure window

When Delta 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 1,011 flights.

5am–8am180 flights87.7%
8am–11am185 flights87.6%
11am–2pm207 flights78.0%
2pm–5pm74 flights84.9%
5pm–8pm365 flights78.2%
8pm–5am—

Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.

The weak window here is the middle of the day, not the evening: 11am–2pm runs 78.0% on time against 87.7% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 5pm–8pm window is the busiest, with 365 flights scheduled in it.

Across the year

Delta on SLC to IAH through the year

Darker means more delays. Figures are on-time percentages.September best, July worst

July is the worst month at 64.4% on time, 25 points below September, the best at 89.6%. 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 89 flights.

Across the week, Tuesday is the strongest day at 84.3% on time and Thursday the weakest at 79.9%. 4 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 61% of the 15,000 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.

Carrier
61%
National Airspace System
16%
Late-arriving aircraft
16%
Extreme weather
7%

The largest share of delay minutes, 61%, 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 8,900 of the 15,000 delay minutes reported here. The split is drawn from 14,621 reported delay minutes.

Cancellations are rare at 0.20%, 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 costs

5.5% 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 82.7% on time across 1,011 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 1,011 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 Delta on SLC to IAH

Put together: treat all of this as provisional. 1,011 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 82.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,005 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures