Route reliability record
LAS→ONT
Las Vegas to Ontario
- Flights
- 2,473
- Period
- September 2025 to August 2026
- Distance
- 197 mi
- Carriers
- 2
This route sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land about 55 minutes behind schedule. That rests on 2,473 LAS to ONT flights, of which Frontier Airlines flew 724 at 80.9% on time.
Best time to fly LAS to ONT: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 91.0% of the time and Tuesday flights 83.7%, against 75.4% for the route overall.
The US average over the same twelve months is 77.3%, 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.
Key figures
On time
75.4%
Arrivals under 15 minutes late, of 2,455 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.69%
National rate is 1.89%
Best carrier
Frontier
80.9% on time across 724 flights
These figures cover 2,473 flights between September 2025 and August 2026. The median arrival is 5 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.
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Carrier by carrier
Which airline is most reliable on LAS to ONT
The choice of carrier is not cosmetic here. Frontier Airlines arrives on time 80.9% of the time; Southwest Airlines manages 73.1%. Sample sizes sit next to every figure, because a two-point gap across 1,749 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Frontier Airlines | 724 | 80.9% | 73 min | 0.83% | B+ |
| Southwest Airlines | 1,749 | 73.1% | 50 min | 0.63% | C+ |
Frontier leads Southwest by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on LAS to ONT
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Las Vegas to Ontario
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 5 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. LAS → SNALas Vegas to Santa Ana | Spirit Airlines | 87.5% | 89.1% | 1.82% | 8pm–5am, Sat | — |
| 2. LAS → SNALas Vegas to Santa Ana | SkyWest Airlines | 86.5% | 87.0% | 0.55% | 2pm–5pm, Wed | OO 4078 08:00 |
| 3. LAS → BURLas Vegas to Burbank | Spirit Airlines | 86.0% | 88.4% | 2.69% | 5am–8am, Tue | — |
| 4. LAS → LAXLas Vegas to Los Angeles | Spirit Airlines | 85.8% | 86.9% | 1.30% | 11am–2pm, Wed | — |
| 5. LAS → LAXLas Vegas to Los Angeles | United Airlines | 85.1% | 85.6% | 0.57% | 5am–8am, Wed | UA 2039 06:00 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 33 points, against 8 points between the best and worst carrier.
- 5am–8am281 flights91.0%
- 8am–11am453 flights89.3%
- 11am–2pm344 flights81.9%
- 2pm–5pm469 flights70.8%
- 5pm–8pm495 flights68.6%
- 8pm–5am431 flights58.1%
Scale runs 50% to 95%.
The 8pm–5am window is where this operation falls apart: 58.1% on time, against 91.0% 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 5pm–8pm window is the busiest, with 495 flights scheduled in it.
Explore
Filter LAS to ONT by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On LAS to ONT, the best departure window is 5am–8am at 91.0% on time and the worst is 8pm–5am at 58.1%, a wide gap of 32.9 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am91.0%
- 8–11am89.3%
- 11am–2pm81.9%
- 2–5pm70.8%
- 5–8pm68.6%
- 8pm–5am58.1%
best all US flightsScale 50% to 95%.
Across the year
When delays peak on this route
This route's year swings by 17 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.
June is the worst month at 65.9% on time, 17 points below January, the best at 82.8%. 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. October was the busiest month here, with 228 flights.
Across the week, Tuesday is the strongest day at 83.7% on time and Sunday the weakest at 70.1%, a spread of 14 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 57% of the 33,000 delay minutes carriers reported here, and the remaining four split what is left.
- 57%Late-arriving aircraft
- 34%Carrier
- 7%National Airspace System
- 2%Extreme weather
- 0%Security
57% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 33,000 reported delay minutes here, that single category outweighs weather by 37 to one. The split is drawn from 33,244 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 91.0% on time here.
Cancellations are rare at 0.69%, below the national 1.89% 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
7.3% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 55 minutes, which a normal layover absorbs.
At 197 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 runs 76.2% on time across 2,469 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 2,473 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.
Work out the risk of missing a connection in ONT after this flight
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 82.8% on time and June 65.9%, a swing of 17 points. If the dates move at all, move them out of June before you think about anything else. 2,455 completed flights over 12 months sit behind that.
Common questions
LAS to ONT questions
How often is LAS to ONT delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.6% of the 2,473 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 55 minutes on average.
Which airline is most reliable on LAS to ONT?
Frontier Airlines leads at 80.9% on time across 724 flights. Southwest Airlines is at the other end on 73.1%, a gap of 8 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 LAS to ONT?
The 5am–8am departure window is the strongest at 91.0% on time. The 8pm–5am window is the weakest at 58.1%, 33 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 LAS to ONT?
June is the weakest month at 65.9% on time, compared with 82.8% in January. Across the year that is 17 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
- ONT to LAS — the return legseparate record
- Harry Reid International (LAS) delay statistics
- Ontario International (ONT) delay statistics
- Frontier Airlines on LAS to ONT80.9%
- Southwest Airlines on LAS to ONT73.1%
- LAS to LAX, a related route77.9%
- PHX to ONT, a related route76.8%
- LAS to DEN, a related route76.5%
- Frontier Airlines on-time record80.9%
- Southwest Airlines on-time record73.1%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. LAS to ONT and ONT to LAS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.