Route reliability record
ONT→PHX
Ontario to Phoenix
- Flights
- 3,059
- Period
- July 2025 to June 2026
- Distance
- 325 mi
- Carriers
- 4
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 a little over 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 83.8% on time.
Set against the rest of the country, this route's record is 5 points better than the US average of 77.6%. That gap is worth roughly 51 fewer late arrivals for every thousand flights.
Key figures
On time
82.7%
Arrivals under 15 minutes late, of 3,039 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.65%
National rate is 1.81%
Best carrier
American
83.8% on time across 1,315 flights
These figures cover 3,059 flights between July 2025 and June 2026. The median arrival is 7 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 ONT to PHX
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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 45 | 88.9% | 29 min | 0.00% | A+ |
| SkyWest Airlinesthin sample | 91 | 85.6% | 59 min | 1.10% | A |
| American Airlines | 1,315 | 83.8% | 101 min | 0.99% | B+ |
| Southwest Airlines | 1,608 | 81.5% | 49 min | 0.37% | B+ |
No carrier stands out. American tops the table at 83.8%, 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 matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against 2 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am748 flights90.2%
- 8am–11am482 flights89.5%
- 11am–2pm603 flights84.6%
- 2pm–5pm512 flights73.9%
- 5pm–8pm570 flights77.0%
- 8pm–5am144 flights68.1%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.2% of the time, against 68.1% for the overnight window. That is 22 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 748 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 14 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.
May is the best month on the calendar at 87.8% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. March was the busiest month here, with 289 flights.
The day of the week is close to irrelevant here: 3 points separates the best day from the worst. Weekly demand peaks are not what drives the delays on this operation.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 37,000 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.
- 46%Late-arriving aircraft
- 38%Carrier
- 15%National Airspace System
- 1%Extreme weather
- 0%Security
46% 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 37,000 reported delay minutes here, that single category outweighs weather by 46 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 36,743 reported delay minutes.
The largest share of delay minutes, 38%, 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 37,000 delay minutes reported 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
5.0% 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.
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 77.7% on time across 3,059 flights, 5 points below 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. May runs 87.8% on time and November 73.6%, a swing of 14 points. If the dates move at all, move them out of November before you think about anything else. 3,039 completed flights over 12 months sit behind that.
Common questions
ONT to PHX questions
How often is ONT to PHX 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 3,059 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 ONT to PHX?
American Airlines leads at 83.8% on time across 1,315 flights. Southwest Airlines is at the other end on 81.5%, 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 ONT to PHX?
The 5am–8am departure window is the strongest at 90.2% on time. The 8pm–5am window is the weakest at 68.1%, 22 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 November delays on ONT to PHX?
November is the weakest month at 73.6% on time, compared with 87.8% in May. Across the year that is 14 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
- PHX to ONT — the return legseparate record
- Phoenix Sky Harbor International (PHX) delay statistics
- Envoy Air on-time record88.9%
- SkyWest Airlines on-time record85.6%
- American Airlines on-time record83.8%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. ONT to PHX and PHX to ONT 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.