Route reliability record

PHX→ONT

Phoenix to Ontario

Flights: 3,059
Period: July 2025 to June 2026
Distance: 325 mi
Carriers: 4

This route lands a B+, level with the national rate of 77.6%. Roughly one flight in four arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 3,059 flights, of which American Airlines flew 1,315 at 80.4% on time.

The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

77.7%

Arrivals under 15 minutes late, of 3,043 completed flights

Avg delay

56 min

Across delayed arrivals only, not all flights

Cancelled

0.52%

National rate is 1.81%

Best carrier

American

80.4% on time across 1,315 flights

These figures cover 3,059 flights between July 2025 and June 2026. The median arrival is 4 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 PHX to ONT

The choice of carrier is not cosmetic here. American Airlines arrives on time 80.4% of the time; Southwest Airlines manages 74.4%. Sample sizes sit next to every figure, because a two-point gap across 1,608 flights means less than a ten-point one.

On-time performance by carrier on PHX to ONT
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	91	91.1%	60 min	1.10%	A
Envoy Airthin sample	45	91.1%	37 min	0.00%	A+
American Airlines	1,315	80.4%	67 min	0.91%	B+
Southwest Airlines	1,608	74.4%	49 min	0.19%	C+

American leads Southwest by 6 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 34 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am100 flights97.0%
8am–11am787 flights89.4%
11am–2pm344 flights80.2%
2pm–5pm642 flights79.8%
5pm–8pm520 flights70.9%
8pm–5am666 flights63.1%

Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 63.1% on time, against 97.0% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 787 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 15 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.January best, June worst

June is the worst month at 68.9% on time, 15 points below January, the best at 84.2%. 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. March was the busiest month here, with 288 flights.

Across the week, Tuesday is the strongest day at 84.4% on time and Sunday the weakest at 72.9%. 12 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 60% of the 38,000 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
60%
Carrier
36%
National Airspace System
4%
Extreme weather
0%
Security
0%

60% 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 38,000 reported delay minutes here, that single category outweighs weather by 60 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 37,797 reported delay minutes.

The largest share of delay minutes, 36%, 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 38,000 delay minutes reported here.

Cancellations are rare at 0.52%, 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

6.6% 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.

At 325 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.

The return leg is a different operation and performs like one: it runs 82.7% on time across 3,059 flights, 5 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 5 points of difference.

The sample behind these figures is 3,059 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. January runs 84.2% on time and June 68.9%, a swing of 15 points. If the dates move at all, move them out of June before you think about anything else. 3,043 completed flights over 12 months sit behind that.

Common questions

PHX to ONT questions

How often is PHX to ONT delayed?

Roughly one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.3% of the 3,059 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on PHX to ONT?

American Airlines leads at 80.4% on time across 1,315 flights. Southwest Airlines is at the other end on 74.4%, 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 PHX to ONT?

The 5am–8am departure window is the strongest at 97.0% on time. The 8pm–5am window is the weakest at 63.1%, 34 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 June delays on PHX to ONT?

June is the weakest month at 68.9% on time, compared with 84.2% in January. Across the year that is 15 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. PHX to ONT and ONT to PHX 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