Carrier route record

DLSAN→SLC

Delta Air Lines · San Diego to Salt Lake City

Flights: 1,732
Period: July 2025 to June 2026
Share of route: 58%
Carriers: 4

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

Delta on SAN to SLC earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 11 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 1,732 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 688 at 78.4% on time.

Set against the rest of the country, Delta's SAN to SLC record is 11 points better than the US average of 77.6%. That gap is worth roughly 111 fewer late arrivals for every thousand flights.

On time

88.7%

Arrivals under 15 minutes late, of 1,714 completed flights

Avg delay

77 min

Across delayed arrivals only, not all flights

Cancelled

0.81%

National rate is 1.81%

Whole route

84.4%

Every carrier on SAN to SLC, 2,961 flights

These figures cover 1,732 flights between July 2025 and June 2026. The median arrival is 9 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 SAN to SLC

Delta flew 1,732 of the 2,961 flights on SAN to SLC, most of the route. Its 88.7% on time is 4 points better than the route as a whole, which runs 84.4%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from Delta at 88.7% to Southwest at 76.6%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The two carriers here are closely matched: 2 points 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.

On-time performance by carrier on SAN to SLC
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	1,732	88.7%	77 min	0.81%	A+
Frontier Airlinesthin sample	133	83.3%	87 min	0.75%	B+
SkyWest Airlines	688	78.4%	61 min	0.73%	B+
Southwest Airlines	408	76.6%	45 min	0.25%	B+

No carrier stands out. SkyWest tops the table at 78.4%, 2 points clear of the bottom, which is inside the range this kind of sample moves year to year.

Flight by flight

Delta flight numbers on SAN to SLC

Departure window

When Delta runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 11 points, against 2 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am365 flights95.3%
8am–11am364 flights91.7%
11am–2pm365 flights86.9%
2pm–5pm1 flights—
5pm–8pm637 flights84.4%
8pm–5am—

Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 95.3% of the time, against 84.4% for the evening 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 5pm–8pm window is the busiest, with 637 flights scheduled in it.

Across the year

Delta on SAN to SLC through the year

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

July is the worst month at 80.8% on time, 16 points below March, the best at 96.6%. 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 151 flights.

Across the week, Monday is the strongest day at 93.7% on time and Friday the weakest at 83.0%. 11 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. Late-arriving aircraft accounts for 56% 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.

Late-arriving aircraft
56%
Carrier
38%
National Airspace System
6%
Extreme weather
0%

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 15,000 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 14,856 reported delay minutes.

The largest share of delay minutes, 38%, 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 5,599 of the 15,000 delay minutes reported here.

Cancellations are rare at 0.81%, 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

Badly late arrivals are rare here: only 4.1% 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 626 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 is a different operation and performs like one: it runs 83.8% on time across 1,731 flights, 5 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 5 points of difference.

The sample behind these figures is 1,732 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.

What to do with this

Booking Delta on SAN to SLC

Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 96.6% on time and July 80.8%, a swing of 16 points. If the dates move at all, move them out of July before you think about anything else. 1,714 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