Route reliability record
SMF→SEA
Sacramento to Seattle
- Flights
- 4,416
- Period
- July 2025 to June 2026
- Distance
- 605 mi
- Carriers
- 3
This route lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrive 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That is a workable record, not a spotless one. That rests on 4,416 flights, of which SkyWest Airlines flew 1,952 at 87.4% on time.
SkyWest Airlines is the most reliable of the three carriers covered here at 87.4% on time across 1,952 flights.
Key figures
On time
82.7%
Arrivals under 15 minutes late, of 4,397 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
0.34%
National rate is 1.81%
Best carrier
SkyWest
87.4% on time across 1,952 flights
These figures cover 4,416 flights between July 2025 and June 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.
Carrier by carrier
Which airline is most reliable on SMF to SEA
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 87.4% of the time; Southwest Airlines manages 77.4%. Sample sizes sit next to every figure, because a two-point gap across 1,155 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 1,952 | 87.4% | 57 min | 0.26% | A+ |
| Alaska Airlines | 1,309 | 80.3% | 42 min | 0.61% | B+ |
| Southwest Airlines | 1,155 | 77.4% | 43 min | 0.17% | B+ |
SkyWest leads Southwest by 10 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 20 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am977 flights92.4%
- 8am–11am484 flights76.3%
- 11am–2pm1,084 flights87.0%
- 2pm–5pm512 flights77.8%
- 5pm–8pm797 flights78.6%
- 8pm–5am562 flights72.9%
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 92.4% of the time, against 72.9% for the overnight window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 1,084 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 13 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.
August is the worst month at 77.3% on time, 13 points below February, the best at 90.1%. 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. July was the busiest month here, with 455 flights.
Across the week, Tuesday is the strongest day at 86.6% on time and Thursday the weakest at 79.3%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 36,000 reported delay minutes.
- 39%Carrier
- 29%Late-arriving aircraft
- 24%National Airspace System
- 8%Extreme weather
- 0%Security
The largest share of delay minutes, 39%, 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 14,000 of the 36,000 delay minutes reported here. The split is drawn from 35,771 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 92.4% on time here.
Cancellations are rare at 0.34%, 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 3.7% 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 605 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 81.9% on time across 4,407 flights, within about a point 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 4,416 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: the calendar is the biggest lever here, not the carrier or the hour. February runs 90.1% on time and August 77.3%, a swing of 13 points. If the dates move at all, move them out of August before you think about anything else. 4,397 completed flights over 12 months sit behind that.
Common questions
SMF to SEA questions
How often is SMF to SEA delayed?
About one flight in six arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.3% of the 4,416 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 45 minutes on average.
Which airline is most reliable on SMF to SEA?
SkyWest Airlines leads at 87.4% on time across 1,952 flights. Southwest Airlines is at the other end on 77.4%, a gap of 10 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 SEA?
The 5am–8am departure window is the strongest at 92.4% on time. The 8pm–5am window is the weakest at 72.9%, 20 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 August delays on SMF to SEA?
August is the weakest month at 77.3% on time, compared with 90.1% in February. Across the year that is 13 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
- SEA to SMF — the return legseparate record
- Sacramento International (SMF) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- SkyWest Airlines on-time record87.4%
- Alaska Airlines on-time record80.3%
- Southwest Airlines on-time record77.4%
- The best time of day to fly, according to 7.04 million flight records
- Do budget airlines really get delayed more? The numbers
Direction matters. SMF to SEA and SEA 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.