Route reliability record
SLC→SAT
Salt Lake City to San Antonio
- Flights
- 1,007
- Period
- July 2025 to June 2026
- Distance
- 1,087 mi
- Carriers
- 1
This route earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 1,007 SLC to SAT flights, with a median arrival 7 minutes early.
Best time to fly SLC to SAT: a 11am–2pm departure, ideally on a Monday. Flights in that window arrived on time 85.8% of the time and Monday flights 88.1%, against 84.1% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.6%. That gap is worth roughly 65 fewer late arrivals for every thousand flights.
Key figures
On time
84.1%
Arrivals under 15 minutes late, of 998 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
0.79%
National rate is 1.81%
Best carrier
Delta
84.1% on time across 1,007 flights
These figures cover 1,007 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 SLC to SAT
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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 1,007 | 84.1% | 65 min | 0.79% | B+ |
Flight by flight
Flights on SLC to SAT
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.
Departure window
The best time of day to leave
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 1,007 flights.
- 5am–8am—
- 8am–11am363 flights85.3%
- 11am–2pm268 flights85.8%
- 2pm–5pm12 flights—
- 5pm–8pm61 flights83.3%
- 8pm–5am303 flights80.9%
Scale runs 70% to 90%. Rows with fewer than 30 flights show a dash.
The 11am–2pm window is the strongest at 85.8% on time. The full set of windows spans 5 points.
Across the year
When delays peak on this route
This route's year swings by 20 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.
July is the worst month at 72.7% on time, 20 points below October, the best at 92.9%. 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, Monday is the strongest day at 88.1% on time and Thursday the weakest at 80.4%. 8 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 70% of the 10,000 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.
- 70%Carrier
- 18%Late-arriving aircraft
- 9%National Airspace System
- 3%Extreme weather
The largest share of delay minutes, 70%, 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 7,147 of the 10,000 delay minutes reported here. The split is drawn from 10,258 reported delay minutes.
Cancellations are rare at 0.79%, 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
5.1% 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 about an hour, which a normal layover absorbs.
The 1,087 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 86.6% on time across 1,008 flights, within 3 points 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. 1,007 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.
Work out the risk of missing a connection in SAT after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,007 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 84.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 998 completed flights over 12 months sit behind that.
Common questions
SLC to SAT questions
How often is SLC to SAT 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 15.9% of the 1,007 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is SLC to SAT compared with the rest of the country?
84.1% of flights arrive on time here against a national 77.6%, a difference of 7 points in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on SLC to SAT?
The 11am–2pm departure window is the strongest at 85.8% on time. The 8pm–5am window is the weakest at 80.9%, 5 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 July delays on SLC to SAT?
July is the weakest month at 72.7% on time, compared with 92.9% in October. Across the year that is 20 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
- SAT to SLC — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- San Antonio International (SAT) delay statistics
- SLC to DEN, a related route77.8%
- DFW to SAT, a related route67.0%
- SLC to PHX, a related route83.9%
- Delta Air Lines on-time record84.1%
- Worst months to fly in the US, ranked by the data
- How to read this site: grades, sample sizes, and honest caveats
Direction matters. SLC to SAT and SAT to SLC 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.