Route reliability record

SLC→SMF

Salt Lake City to Sacramento

Flights: 2,158
Period: July 2025 to June 2026
Distance: 532 mi
Carriers: 3

This route earns a 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 8 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 2,158 flights, of which Delta Air Lines flew 1,509 at 87.3% on time.

Set against the rest of the country, this route's record is 8 points better than the US average of 77.6%. That gap is worth roughly 81 fewer late arrivals for every thousand flights.

On time

85.7%

Arrivals under 15 minutes late, of 2,142 completed flights

Avg delay

61 min

Across delayed arrivals only, not all flights

Cancelled

0.70%

National rate is 1.81%

Best carrier

Delta

87.3% on time across 1,509 flights

These figures cover 2,158 flights between July 2025 and June 2026. The median arrival is 10 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 SMF

The two carriers here are closely matched: 6 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 SLC to SMF
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,509	87.3%	63 min	0.86%	A+
SkyWest Airlinesthin sample	73	84.9%	57 min	0.00%	B+
Southwest Airlines	576	81.7%	57 min	0.35%	B+

No carrier stands out. Delta tops the table at 87.3%, 6 points clear of the bottom, which is inside the range this kind of sample moves year to year.

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 19 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am135 flights97.0%
8am–11am467 flights92.2%
11am–2pm334 flights84.7%
2pm–5pm425 flights83.8%
5pm–8pm335 flights78.1%
8pm–5am462 flights83.9%

Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 97.0% of the time, against 78.1% for the evening window. That is 19 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 467 flights scheduled in it.

Across the year

When delays peak on this route

Twelve months, one bar each, drawn from the same 2,158 flights. The strip shows how much of this route's record is set by the calendar rather than by the operation.

Darker means more delays. Figures are on-time percentages.May best, October worst

May is the best month on the calendar at 91.0% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. July was the busiest month here, with 204 flights.

Across the week, Tuesday is the strongest day at 88.6% on time and Friday the weakest at 83.9%. 5 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 52% of the 19,000 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
52%
Late-arriving aircraft
41%
National Airspace System
5%
Extreme weather
2%

41% 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 19,000 reported delay minutes here, that single category outweighs weather by 20 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 18,549 reported delay minutes.

The largest share of delay minutes, 52%, 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 9,694 of the 19,000 delay minutes reported here.

Cancellations are rare at 0.70%, 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 are the about an hour kind, which a normal layover absorbs.

The 532 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 87.6% on time across 2,158 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.

The sample behind these figures is 2,158 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 this route

Put together: avoid the 5pm–8pm departure. It runs 78.1% on time against 97.0% for the 5am–8am slot, and that 19 points is the largest single thing you control here. Delta Air Lines is the strongest operator if the fares are close. 2,142 completed flights over 12 months sit behind that.

Common questions

SLC to SMF questions

How often is SLC to SMF delayed?

About one flight in seven arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 14.3% of the 2,158 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on SLC to SMF?

Delta Air Lines leads at 87.3% on time across 1,509 flights. Southwest Airlines is at the other end on 81.7%, a gap of 6 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on SLC to SMF?

The 5am–8am departure window is the strongest at 97.0% on time. The 5pm–8pm window is the weakest at 78.1%, 19 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 October delays on SLC to SMF?

October is the weakest month at 80.1% on time, compared with 91.0% in May. Across the year that is 11 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. SLC to SMF and SMF to SLC are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures