Route reliability record

PDX→LAX

Portland to Los Angeles

Flights: 4,403
Period: July 2025 to June 2026
Distance: 833 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 a little over an hour. That rests on 4,403 flights, of which Delta Air Lines flew 1,689 at 90.9% on time.

Delta Air Lines is the most reliable of the three carriers covered here at 90.9% on time across 1,689 flights.

On time

87.4%

Arrivals under 15 minutes late, of 4,363 completed flights

Avg delay

79 min

Across delayed arrivals only, not all flights

Cancelled

0.89%

National rate is 1.81%

Best carrier

Delta

90.9% on time across 1,689 flights

These figures cover 4,403 flights between July 2025 and June 2026. The median arrival is 11 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 PDX to LAX

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 90.9% of the time; SkyWest Airlines manages 81.0%. Sample sizes sit next to every figure, because a two-point gap across 599 flights means less than a ten-point one.

On-time performance by carrier on PDX to LAX
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,689	90.9%	108 min	0.89%	A+
Alaska Airlines	1,897	86.5%	49 min	0.84%	A+
Frontier Airlinesthin sample	218	84.9%	52 min	2.75%	B
SkyWest Airlines	599	81.0%	117 min	0.33%	B+

Delta leads SkyWest 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 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 4,403 flights.

5am–8am1,005 flights90.0%
8am–11am622 flights87.4%
11am–2pm751 flights90.2%
2pm–5pm554 flights83.7%
5pm–8pm905 flights86.4%
8pm–5am566 flights84.4%

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

The best window here is not the first bank but the 11am–2pm slot at 90.2% on time, ahead of 2pm–5pm at 83.7%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 5am–8am window is the busiest, with 1,005 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 12 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.September best, December worst

December is the weak month at 80.2% on time, against 92.2% in September. 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. August was the busiest month here, with 412 flights.

Across the week, Wednesday is the strongest day at 90.5% on time and Sunday the weakest at 84.6%. 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. Carrier accounts for 52% of the 44,000 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
39%
National Airspace System
8%
Extreme weather
1%
Security
0%

39% 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 44,000 reported delay minutes here, that single category outweighs weather by 39 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 43,763 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 23,000 of the 44,000 delay minutes reported here.

Cancellations are rare at 0.89%, 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 4.5% 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 833 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 86.4% on time across 4,406 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 4,403 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. September runs 92.2% on time and December 80.2%, a swing of 12 points. If the dates move at all, move them out of December before you think about anything else. 4,363 completed flights over 12 months sit behind that.

Common questions

PDX to LAX questions

How often is PDX to LAX 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 12.6% of the 4,403 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 PDX to LAX?

Delta Air Lines leads at 90.9% on time across 1,689 flights. SkyWest Airlines is at the other end on 81.0%, 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 PDX to LAX?

The 11am–2pm departure window is the strongest at 90.2% on time. The 2pm–5pm window is the weakest at 83.7%, 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 December delays on PDX to LAX?

December is the weakest month at 80.2% on time, compared with 92.2% in September. Across the year that is 12 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. PDX to LAX and LAX to PDX 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