Route reliability record
SAT→SLC
San Antonio to Salt Lake City
- Flights
- 1,008
- Period
- July 2025 to June 2026
- Distance
- 1,087 mi
- Carriers
- 1
This route earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 1,008 SAT to SLC flights, with a median arrival 11 minutes early.
Best time to fly SAT to SLC: a 8am–11am departure, ideally on a Sunday. Flights in that window arrived on time 100.0% of the time and Sunday flights 89.4%, against 86.6% for the route overall.
Set against the rest of the country, this route's record is 9 points better than the US average of 77.6%. That gap is worth roughly 90 fewer late arrivals for every thousand flights.
Key figures
On time
86.6%
Arrivals under 15 minutes late, of 997 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.89%
National rate is 1.81%
Best carrier
Delta
86.6% on time across 1,008 flights
These figures cover 1,008 flights between July 2025 and June 2026. The median arrival is 11 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 SAT to SLC
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 | 1,008 | 86.6% | 70 min | 0.89% | A+ |
Flight by flight
Flights on SAT 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.
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 21 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–8am323 flights94.0%
- 8am–11am41 flights100.0%
- 11am–2pm317 flights78.9%
- 2pm–5pm39 flights92.3%
- 5pm–8pm288 flights83.9%
- 8pm–5am—
Scale runs 70% to 100%. 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 78.9% on time against 100.0% for 8am–11am. 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 5am–8am window is the busiest, with 323 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 17 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.
Delays peak in September, when the on-time rate falls to 76.3%. March is the strongest month at 93.2%. Moving a flexible trip across that boundary buys 17 points. March was the busiest month here, with 89 flights.
Across the week, Sunday is the strongest day at 89.4% on time and Thursday the weakest at 81.0%. 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. Late-arriving aircraft accounts for 56% of the 9,379 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.
- 56%Late-arriving aircraft
- 37%Carrier
- 7%National Airspace System
- 1%Extreme weather
56% 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 9,379 reported delay minutes here, that single category outweighs weather by 56 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 9,379 reported delay minutes.
The largest share of delay minutes, 37%, 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 3,453 of the 9,379 delay minutes reported here.
Cancellations are rare at 0.89%, 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
Badly late arrivals are rare here: only 4.3% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 84.1% on time across 1,007 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. 1,008 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 SLC after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,008 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 86.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 997 completed flights over 12 months sit behind that.
Common questions
SAT to SLC questions
How often is SAT to SLC delayed?
About one flight in seven arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 13.4% of the 1,008 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
How reliable is SAT to SLC compared with the rest of the country?
86.6% of flights arrive on time here against a national 77.6%, a difference of 9 points in its favour. That is worth a A+ on this site's grading scale.
What time of day has the fewest delays on SAT to SLC?
The 8am–11am departure window is the strongest at 100.0% on time. The 11am–2pm window is the weakest at 78.9%, 21 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 September delays on SAT to SLC?
September is the weakest month at 76.3% on time, compared with 93.2% in March. Across the year that is 17 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 SAT — the return legseparate record
- San Antonio International (SAT) delay statistics
- Salt Lake City International (SLC) delay statistics
- SAT to DFW, a related route77.1%
- DEN to SLC, a related route77.5%
- SAT to DEN, a related route81.0%
- Delta Air Lines on-time record86.6%
- 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. SAT to SLC and SLC to SAT 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.