Route reliability record

SMF→SLC

Sacramento to Salt Lake City

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

This route earns a 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 10 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 2,158 flights, of which Delta Air Lines flew 1,509 at 89.7% on time.

Set against the rest of the country, this route's record is 10 points better than the US average of 77.6%. That gap is worth roughly 100 fewer late arrivals for every thousand flights.

On time

87.6%

Arrivals under 15 minutes late, of 2,143 completed flights

Avg delay

72 min

Across delayed arrivals only, not all flights

Cancelled

0.65%

National rate is 1.81%

Best carrier

Delta

89.7% on time across 1,509 flights

These figures cover 2,158 flights between July 2025 and June 2026. The median arrival is 12 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 SMF to SLC

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 89.7% of the time; Southwest Airlines manages 81.6%. Sample sizes sit next to every figure, because a two-point gap across 576 flights means less than a ten-point one.

On-time performance by carrier on SMF to SLC
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	73	91.8%	64 min	0.00%	A+
Delta Air Lines	1,509	89.7%	80 min	0.86%	A+
Southwest Airlines	576	81.6%	60 min	0.17%	B+

Delta leads Southwest by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

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 24 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am459 flights96.1%
8am–11am548 flights93.8%
11am–2pm417 flights88.2%
2pm–5pm29 flights—
5pm–8pm622 flights78.9%
8pm–5am83 flights72.3%

Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 96.1% of the time, against 72.3% for the overnight window. That is 24 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 622 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.November best, December worst

December is the weak month at 84.8% on time, against 91.1% in November. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 204 flights.

Across the week, Saturday is the strongest day at 90.2% on time and Friday the weakest at 84.5%. 6 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 63% 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.

Late-arriving aircraft
63%
Carrier
33%
National Airspace System
4%
Extreme weather
1%

63% 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 63 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 19,136 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 96.1% on time here.

Cancellations are rare at 0.65%, 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 a little over 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 85.7% 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 8pm–5am departure. It runs 72.3% on time against 96.1% for the 5am–8am slot, and that 24 points is the largest single thing you control here. Delta Air Lines is the strongest operator if the fares are close. 2,143 completed flights over 12 months sit behind that.

Common questions

SMF to SLC questions

How often is SMF to SLC delayed?

About one flight in eight arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 12.4% of the 2,158 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.

Which airline is most reliable on SMF to SLC?

Delta Air Lines leads at 89.7% on time across 1,509 flights. Southwest Airlines is at the other end on 81.6%, a gap of 8 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 SMF to SLC?

The 5am–8am departure window is the strongest at 96.1% on time. The 8pm–5am window is the weakest at 72.3%, 24 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 December delays on SMF to SLC?

December is the weakest month at 84.8% on time, compared with 91.1% in November. Across the year that is 6 points between the best and worst months. The seasonal swing is modest enough that it should not decide when you travel.

Where to go next

Direction matters. SMF to SLC and SLC to SMF 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