Route on-time record
ONT to LAS: most on-time flights and the best time to fly
Ontario (Ontario International Airport) to Las Vegas (Harry Reid International Airport). 2,484 nonstop flights in Jun 2025 to May 2026, 78% arrived within 15 minutes and 0.8% were cancelled. The most reliable flight number was Southwest 1695 at 5:30 AM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
ONT → LAS
Ontario to Las Vegas: 2,484 nonstop flights a year
On time (12 months)
78%
Cancelled
0.8%
avg delay 15 min
Best time to leave
Before 9 AM
94% on time vs 66% 6 to 9 PM
Most reliable airline
Frontier
78% chance on time
Lowest nonstop fare seen in the next two months: $64 (Frontier 2232 on 2026-11-18). Fares open on our travel partner (Aviasales). Pick the flight number you chose here.
Most reliable nonstop flights
Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.
#1 · Southwest 1695
5:30 AM → 6:35 AM1h 05m nonstop
Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as Southwest 2374; its record covers all of them.
96%
chance on time
- On time (history)
- 100%
- Cancelled
- 0.0%
- Avg arrival delay
- 0 min
- Arrived on time 100% of the time (63 flights, Jun 2025 to May 2026).
- Never cancelled in 63 scheduled flights.
- Leaves in this route's most on-time window (Before 9 AM: 94% on time; 6 to 9 PM: 66%).
Moderate track record · 63 flights
Find Southwest 1695 fares Opens this date on Aviasales#2 · Southwest 4072
8:00 AM → 9:15 AM1h 10m nonstop
Local times, typical schedule. Last flown 2026-04-06.
87%
chance on time
- On time (history)
- 88%
- Cancelled
- 0.0%
- Avg arrival delay
- 5 min
- Arrived on time 88% of the time (33 flights, Jun 2025 to May 2026).
- Never cancelled in 33 scheduled flights.
- Leaves in this route's most on-time window (Before 9 AM: 94% on time; 6 to 9 PM: 66%).
- Short track record (33 flights), so its score leans on the airline's record at this hour.
Limited track record · 33 flights
Find Southwest 4072 fares Opens this date on Aviasales#3 · Southwest 322
9:25 AM → 10:30 AM1h 05m nonstop
Local times, typical schedule. Last flown 2026-05-31.
87%
chance on time
- On time (history)
- 89%
- Cancelled
- 0.0%
- Avg arrival delay
- 6 min
- Arrived on time 89% of the time (54 flights, Jun 2025 to May 2026).
- Never cancelled in 54 scheduled flights.
- Lands inside LAS's trouble window: 51% of its 104 ground stops and delay programs started between 10 AM and 4 PM.
- Short track record (54 flights), so its score leans on the airline's record at this hour.
Limited track record · 54 flights
Find Southwest 322 fares Opens this date on Aviasales#4 · Frontier 2232
11:44 AM → 1:02 PM1h 13m nonstop
Local times, typical schedule. Last flown 2026-05-31.
87%
chance on time
- On time (history)
- 88%
- Cancelled
- 0.7%
- Avg arrival delay
- 15 min
- Arrived on time 88% of the time (292 flights, Jun 2025 to May 2026).
- Lands inside LAS's trouble window: 51% of its 104 ground stops and delay programs started between 10 AM and 4 PM.
Strong track record · 292 flights
Find Frontier 2232 fares Opens this date on Aviasales#5 · Southwest 3556
6:30 PM → 7:35 PM1h 05m nonstop
Local times, typical schedule. Last flown 2026-04-06.
82%
chance on time
- On time (history)
- 95%
- Cancelled
- 0.0%
- Avg arrival delay
- 3 min
- Arrived on time 95% of the time (20 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (6 to 9 PM: 66% on time; Before 9 AM: 94%).
- Short track record (20 flights), so its score leans on the airline's record at this hour.
Limited track record · 20 flights
Find Southwest 3556 fares Opens this date on Aviasales#6 · Frontier 1358
8:44 AM → 9:59 AM1h 14m nonstop
Local times, typical schedule. Last flown 2026-05-18.
82%
chance on time
- On time (history)
- 82%
- Cancelled
- 1.4%
- Avg arrival delay
- 18 min
- Arrived on time 82% of the time (137 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 94% on time; 6 to 9 PM: 66%).
Moderate track record · 137 flights
Find Frontier 1358 fares Opens this date on Aviasales#7 · Southwest 4212
10:35 AM → 11:40 AM1h 05m nonstop
Local times, typical schedule. Last flown 2026-04-01.
80%
chance on time
- On time (history)
- 88%
- Cancelled
- 0.0%
- Avg arrival delay
- 8 min
- Arrived on time 88% of the time (8 flights, Jun 2025 to May 2026).
- Lands inside LAS's trouble window: 51% of its 104 ground stops and delay programs started between 10 AM and 4 PM.
- Short track record (8 flights), so its score leans on the airline's record at this hour.
Limited track record · 8 flights
Find Southwest 4212 fares Opens this date on Aviasales#8 · Southwest 249
10:55 AM → 12:00 PM1h 05m nonstop
Local times, typical schedule. Last flown 2026-05-27.
78%
chance on time
- On time (history)
- 69%
- Cancelled
- 0.0%
- Avg arrival delay
- 9 min
- Arrived on time 69% of the time (16 flights, Jun 2025 to May 2026).
- Lands inside LAS's trouble window: 51% of its 104 ground stops and delay programs started between 10 AM and 4 PM.
- Short track record (16 flights), so its score leans on the airline's record at this hour.
Limited track record · 16 flights
Find Southwest 249 fares Opens this date on Aviasales#9 · Southwest 3512
4:25 PM → 5:35 PM1h 10m nonstop
Local times, typical schedule. Last flown 2026-04-06.
76%
chance on time
- On time (history)
- 75%
- Cancelled
- 0.0%
- Avg arrival delay
- 9 min
- Arrived on time 75% of the time (28 flights, Jun 2025 to May 2026).
- Short track record (28 flights), so its score leans on the airline's record at this hour.
Limited track record · 28 flights
Find Southwest 3512 fares Opens this date on Aviasales#10 · Southwest 4138
2:20 PM → 3:25 PM1h 05m nonstop
Local times, typical schedule. Last flown 2026-04-01.
76%
chance on time
- On time (history)
- 88%
- Cancelled
- 0.0%
- Avg arrival delay
- 6 min
- Arrived on time 88% of the time (8 flights, Jun 2025 to May 2026).
- Lands inside LAS's trouble window: 51% of its 104 ground stops and delay programs started between 10 AM and 4 PM.
- Short track record (8 flights), so its score leans on the airline's record at this hour.
Limited track record · 8 flights
Find Southwest 4138 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- Frontier Airlines78%
721 flights · 78% on time as flown · 1.1% cancel
- Southwest Airlines77%
1,763 flights · 78% on time as flown · 0.7% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM94%
747 flights · avg delay 6 min
- 9 AM to noon83%
312 flights · avg delay 9 min
- Noon to 3 PM69%
339 flights · avg delay 21 min
- 3 to 6 PM67%
485 flights · avg delay 22 min
- 6 to 9 PM66%
329 flights · avg delay 25 min
- After 9 PM70%
272 flights · avg delay 17 min
Best day: Saturday (86%). Worst: Friday (71%).
Smarter routing
Nearby airports that run more on time
SNA → LAS 83% chance on time
John Wayne Orange County International Airport to Harry Reid International Airport · 4,386 flights a year · 30 mi from your airports · yours: 77%
LGB → LAS 81% chance on time
Long Beach International Airport to Harry Reid International Airport · 2,188 flights a year · 36 mi from your airports · yours: 77%
BUR → LAS 80% chance on time
Hollywood Burbank/Bob Hope Airport to Harry Reid International Airport · 4,281 flights a year · 44 mi from your airports · yours: 77%
On time by month
All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.
What delays this route
- Late-arriving aircraft54%
- Air traffic control and airport volume29%
- Airline (crew, maintenance, boarding)16%
Share of delay minutes by the cause airlines report to the US DOT.
Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure
ONT to LAS questions
- What time of day is best to fly ONT to LAS?
- Before 9 AM: 94% of flights arrived on time, against 66% for departures 6 to 9 PM. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
- Which airline is most on time from ONT to LAS?
- Frontier, with a season-adjusted 78% chance of operating and arriving on time over 721 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
- What is the worst month for delays on ONT to LAS?
- May (72% on time); the best was December (87%), averaged over Jun 2023 to May 2026.
- Is this a prediction for my flight?
- No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.
More routes from ONT
- LAS to ONT (return)
- ONT to PHX 83%
- ONT to DEN 79%
- ONT to SEA 86%
- ONT to DFW 78%
- ONT to SMF 86%
- ONT to OAK 87%
- ONT to SJC 86%
- ONT to SFO 69%
- ONT to SLC 91%
- ONT to ATL 90%
- ONT to PDX 88%
- ONT to IAH 85%
Live status: FAA delays and ground stops