Route reliability record

SLC→PDX

Salt Lake City to Portland

Flights: 2,382
Period: July 2025 to June 2026
Distance: 630 mi
Carriers: 4

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 about an hour. That rests on 2,382 flights, of which SkyWest Airlines flew 596 at 89.2% 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 101 fewer late arrivals for every thousand flights.

On time

87.7%

Arrivals under 15 minutes late, of 2,359 completed flights

Avg delay

60 min

Across delayed arrivals only, not all flights

Cancelled

0.97%

National rate is 1.81%

Best carrier

SkyWest

89.2% on time across 596 flights

These figures cover 2,382 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 PDX

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 SLC to PDX
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlinesthin sample	46	97.8%	17 min	0.00%	A+
SkyWest Airlines	596	89.2%	64 min	0.50%	A+
Delta Air Lines	1,697	87.5%	55 min	1.12%	A
Frontier Airlinesthin sample	43	64.3%	117 min	2.33%	D

No carrier stands out. SkyWest tops the table at 89.2%, 2 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 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 2,382 flights.

5am–8am43 flights87.8%
8am–11am618 flights90.5%
11am–2pm507 flights88.7%
2pm–5pm454 flights88.3%
5pm–8pm342 flights83.5%
8pm–5am418 flights85.4%

Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.

The early departures do better, though not dramatically: 90.5% on time for the 8am–11am window against 83.5% for 5pm–8pm. Worth taking if the schedule allows, not worth an extra connection. The 8am–11am window is the busiest, with 618 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.

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

July is the worst month at 79.7% on time, 13 points below May, the best at 92.6%. 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. July was the busiest month here, with 247 flights.

Across the week, Tuesday is the strongest day at 91.7% on time and Sunday the weakest at 85.0%. 7 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 17,000 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
38%
National Airspace System
8%
Extreme weather
3%

38% 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 17,000 reported delay minutes here, that single category outweighs weather by 14 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 17,327 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 8,970 of the 17,000 delay minutes reported here.

Cancellations sit at 0.97% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here actually costs

Badly late arrivals are rare here: only 4.0% 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 630 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 88.5% on time across 2,381 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 2,382 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. May runs 92.6% on time and July 79.7%, a swing of 13 points. If the dates move at all, move them out of July before you think about anything else. 2,359 completed flights over 12 months sit behind that.

Common questions

SLC to PDX questions

How often is SLC to PDX 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 12.3% of the 2,382 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 PDX?

SkyWest Airlines leads at 89.2% on time across 596 flights. Delta Air Lines is at the other end on 87.5%, a gap of 2 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 PDX?

The 8am–11am departure window is the strongest at 90.5% on time. The 5pm–8pm window is the weakest at 83.5%, 7 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 July delays on SLC to PDX?

July is the weakest month at 79.7% on time, compared with 92.6% in May. 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.

Where to go next

Direction matters. SLC to PDX and PDX 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