Carrier route record
WNONT→PHX
Southwest Airlines · Ontario to Phoenix
- Flights
- 1,608
- Period
- July 2025 to June 2026
- Share of route
- 53%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on ONT to PHX lands a B+, 4 points better than the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about 50 minutes on average. That is a workable record, not a spotless one. That rests on 1,608 flights, with a median arrival 4 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on ONT to PHX from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
81.5%
Arrivals under 15 minutes late, of 1,602 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
0.37%
National rate is 1.81%
Whole route
82.7%
Every carrier on ONT to PHX, 3,059 flights
These figures cover 1,608 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
Southwest against every carrier on ONT to PHX
Southwest flew 1,608 of the 3,059 flights on ONT to PHX, most of the route. Its 81.5% on time is about level with the route as a whole at 82.7%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from Envoy at 88.9% to Southwest at 81.5%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| 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 (this page) | 1,608 | 81.5% | 49 min | 0.37% | B+ |
Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 24 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am386 flights91.1%
- 8am–11am287 flights88.1%
- 11am–2pm241 flights86.2%
- 2pm–5pm325 flights72.9%
- 5pm–8pm259 flights72.6%
- 8pm–5am110 flights67.3%
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 91.1% of the time, against 67.3% for the overnight window. That is 24 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 386 flights scheduled in it.
Across the year
Southwest on ONT to PHX through the year
Delays peak in October, when the on-time rate falls to 69.5%. January is the strongest month at 90.0%. Moving a flexible trip across that boundary buys 21 points. December was the busiest month here, with 145 flights.
Across the week, Saturday is the strongest day at 84.0% on time and Sunday the weakest at 77.5%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 53% of the 15,000 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.
- 53%Late-arriving aircraft
- 25%National Airspace System
- 22%Carrier
- 0%Security
53% 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 15,000 reported delay minutes here, that single category outweighs weather by 53 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 14,539 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 91.1% on time here.
Cancellations are rare at 0.37%, 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 costs
Badly late arrivals are rare here: only 4.1% 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.
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 74.4% on time across 1,608 flights, 7 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 7 points of difference.
The sample behind these figures is 1,608 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 Southwest on ONT to PHX
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 90.0% on time and October 69.5%, a swing of 21 points. If the dates move at all, move them out of October before you think about anything else. 1,602 completed flights over 12 months sit behind that.
Related
Where to go next
- ONT to PHX, every carrier
- Southwest on PHX to ONT, the return leg
- American Airlines on ONT to PHX83.8%
- Southwest Airlines network-wide record
- Phoenix Sky Harbor International (PHX) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.