Skip to content

All Products

Aviation Intelligence

Alerts & Airspace

Free Pilot Tools & Widgets

RC Aviation

Games & Learning

Weather Research & More

Pilot Resources

My Airports

Your shortcuts, saved on this device. Search to add an airport.

No airports saved yet. Add the fields you visit most.

Ask ATIS

ATIS Alerts Smart Flight Search

Find the flight least likely to be delayed

Beta

We rank real flight numbers by how often they flew and arrived on time over the last 12 months, adjusted for your travel month and departure time, then check nearby airports and calmer connections. US airlines and airports.

ONT → SEA

Ontario to Seattle: 2,577 nonstop flights a year

On time (12 months)

86%

Cancelled

1.2%

avg delay 10 min

Best time to leave

Before 9 AM

93% on time vs 65% 6 to 9 PM

Most reliable airline

SkyWest

91% chance on time

Check ONT to SEA fares

Fares open on our travel partner (Aviasales). Pick the flight number you chose here.

Best trips

13 nonstop, 27 with 1 connection. Best overall weighs the chance you arrive on time as booked, connection odds, travel time and separate tickets.

  1. Best overall#1 · Nonstop · 3h 07m

    7:00 AM → 10:07 AM

    96%

    arrive on time

    7:00 AM ONT → 10:07 AM SEA3h 07m

    SkyWest 3690 · sold as United Express, Delta Connection, American Eagle or Alaska

    Embraer E175 · 4–19 yrs old
    96% on time · 0.3% cancel
    Find 7:00 AM flight fares Opens this date on Aviasales

  2. #2 · Nonstop · 3h 04m

    6:45 AM → 9:49 AM

    95%

    arrive on time

    6:45 AM ONT → 9:49 AM SEA3h 04m

    SkyWest 3816 · sold as United Express, Delta Connection, American Eagle or Alaska

    Embraer E175 · 4–19 yrs old
    95% on time · 0.3% cancel
    Find 6:45 AM flight fares Opens this date on Aviasales

  3. #3 · Nonstop · 2h 55m

    6:00 AM → 8:55 AM

    94%

    arrive on time

    6:00 AM ONT → 8:55 AM SEA2h 55m

    SkyWest 4042 · sold as United Express, Delta Connection, American Eagle or Alaska

    Embraer E175 · 7–8 yrs old
    94% on time · 0.1% cancel
    Find 6:00 AM flight fares Opens this date on Aviasales

  4. #4 · Nonstop · 3h 03m

    11:59 AM → 2:55 PM

    92%

    arrive on time

    11:59 AM ONT → 2:55 PM SEA3h 03m

    SkyWest 4070 · sold as United Express, Delta Connection, American Eagle or Alaska

    Embraer E175 · 4–10 yrs old
    92% on time · 0.2% cancel
    Find 11:59 AM flight fares Opens this date on Aviasales

  5. #5 · Nonstop · 3h 04m

    2:20 PM → 5:24 PM

    92%

    arrive on time

    2:20 PM ONT → 5:24 PM SEA3h 04m

    SkyWest 4170 · sold as United Express, Delta Connection, American Eagle or Alaska

    Embraer E175 · 4–19 yrs old
    92% on time · 0.3% cancel
    Find 2:20 PM flight fares Opens this date on Aviasales

  6. #6 · Nonstop · 2h 54m

    6:00 AM → 8:54 AM

    90%

    arrive on time

    6:00 AM ONT → 8:54 AM SEA2h 54m

    Alaska 607

    Boeing 737 MAX 9 or 737-900ER · 2–27 yrs old
    91% on time · 1.5% cancel
    Find Alaska 607 fares Opens this date on Aviasales

  7. #7 · Nonstop · 3h 00m

    5:53 PM → 8:50 PM

    90%

    arrive on time

    5:53 PM ONT → 8:50 PM SEA3h 00m

    SkyWest 4031 · sold as United Express, Delta Connection, American Eagle or Alaska

    Embraer E175 · 4–18 yrs old
    91% on time · 0.3% cancel
    Find 5:53 PM flight fares Opens this date on Aviasales

  8. #8 · Nonstop · 3h 00m

    1:35 PM → 4:35 PM

    88%

    arrive on time

    1:35 PM ONT → 4:35 PM SEA3h 00m

    SkyWest 3840 · sold as United Express, Delta Connection, American Eagle or Alaska

    Embraer E175 · 4–18 yrs old
    88% on time · 0.3% cancel
    Find 1:35 PM flight fares Opens this date on Aviasales

  9. #9 · Nonstop · 2h 50m

    10:33 AM → 1:23 PM

    86%

    arrive on time

    10:33 AM ONT → 1:23 PM SEA2h 50m

    Alaska 654

    Boeing 737-900ER or 737 MAX 9 · 2–16 yrs old
    89% on time · 3.0% cancel
    Find Alaska 654 fares Opens this date on Aviasales

  10. #10 · Nonstop · 2h 51m

    3:26 PM → 6:17 PM

    86%

    arrive on time

    3:26 PM ONT → 6:17 PM SEA2h 51m

    Alaska 729

    Boeing 737 MAX 9 or 737-900ER · 2–17 yrs old
    88% on time · 1.8% cancel
    Find Alaska 729 fares Opens this date on Aviasales

Aircraft and ages come from the planes each flight number actually flew in the last 3 months of data (FAA registry build years); airlines can swap planes.

Airlines on this route

Season-adjusted chance of operating and arriving on time.

  • SkyWest Airlines (sold as United Express, Delta Connection, American Eagle or Alaska)91%

    1,113 flights · 92% on time as flown · 0.4% cancel

  • Frontier Airlines85%

    171 flights · 84% on time as flown · 0.6% cancel

  • Alaska Airlines80%

    1,264 flights · 82% on time as flown · 2.1% cancel

On time by departure time

All airlines, scheduled local departure, Jun 2025 to May 2026.

  • Before 9 AM93%

    744 flights · avg delay 6 min

  • 9 AM to noon91%

    575 flights · avg delay 7 min

  • Noon to 3 PM79%

    328 flights · avg delay 13 min

  • 3 to 6 PM87%

    659 flights · avg delay 10 min

  • 6 to 9 PM65%

    271 flights · avg delay 23 min

Best day: Saturday (88%). Worst: Friday (84%).

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