Route reliability record
SLC→SAT
Salt Lake City to San Antonio
- Flights
- 1,013
- Period
- September 2025 to August 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 77.3%. When something does go wrong the average delay runs about an hour. That rests on 1,013 SLC to SAT flights, with a median arrival 8 minutes early.
Best time to fly SLC to SAT: a 8am–11am departure, ideally on a Monday. Flights in that window arrived on time 85.0% of the time and Monday flights 88.3%, against 84.5% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.3%. That gap is worth roughly 72 fewer late arrivals for every thousand flights.
Key figures
On time
84.5%
Arrivals under 15 minutes late, of 1,004 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
0.79%
National rate is 1.89%
Best carrier
Delta
84.5% on time across 1,013 flights
These figures cover 1,013 flights between September 2025 and August 2026. The median arrival is 8 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.
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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 | 1,013 | 84.5% | 62 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.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 1,013 flights.
- 5am–8am—
- 8am–11am363 flights85.0%
- 11am–2pm274 flights84.7%
- 2pm–5pm12 flights—
- 5pm–8pm56 flights83.6%
- 8pm–5am308 flights83.6%
Scale runs 75% to 90%. Rows with fewer than 30 flights show a dash.
The overnight block holds up unusually well at 83.6% on time across 308 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8am–11am window is the busiest, with 363 flights scheduled in it.
Explore
Filter SLC to SAT by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SLC to SAT, the best departure window is 8am–11am at 85.0% on time and the worst is 5pm–8pm at 83.6%, a narrow gap of 1.4 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am—
- 8–11am85.0%
- 11am–2pm84.7%
- 2–5pm—
- 5–8pm83.6%
- 8pm–5am83.6%
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
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.
July is the worst month at 78.7% on time, 14 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 88.3% on time and Sunday the weakest at 79.5%, a spread of 9 points.
Delay causes
Why this route gets delayed
Carrier accounts for 68% of the 9,639 delay minutes carriers reported here, and the remaining four split what is left.
- 68%Carrier
- 18%Late-arriving aircraft
- 9%National Airspace System
- 4%Extreme weather
The largest share of delay minutes, 68%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 6,584 of the 9,639 delay minutes reported here. The split is drawn from 9,639 reported delay minutes.
Cancellations are rare at 0.79%, below the national 1.89% 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 4.5% land an hour or more behind schedule, against 8.3% 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.
The return leg runs 86.9% on time across 1,014 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.
One caution: this is a thin sample. 1,013 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. 1,013 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 84.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,004 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 15.5% of the 1,013 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is SLC to SAT compared with the rest of the country?
84.5% of flights arrive on time here against a national 77.3%, 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 8am–11am departure window is the strongest at 85.0% on time. The 8pm–5am window is the weakest at 83.6%, about a point 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 78.7% on time, compared with 92.9% in October. 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
- 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 route79.0%
- DFW to SAT, a related route67.8%
- SLC to PHX, a related route83.5%
- Delta Air Lines on-time record84.5%
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.