Ontario (ONT) to Seattle (SEA) flights
Alaska Airlines, SkyWest Airlines, Frontier Airlines fly nonstop from Ontario International Airport to Seattle-Tacoma International Airport, with about 57 flights a week in July 2026. The 956-mile flight takes about 2h 46m gate to gate.
- Distance
- 956 mi · 1,539 km
- Flight time
- 2h 46m
- Airlines
- 3
- Seats filled
- 82%
Airlines flying ONT to SEA
| Airline | Flights a week | Aircraft | Passengers (12 months) | Flight time |
|---|---|---|---|---|
| Alaska Airlines | 31 | Boeing 737-900ER, Boeing 737 MAX 9, Boeing 737-800 | 175,128 | 2h 42m |
| SkyWest Airlines | 19 | Embraer E175 | 64,499 | 2h 51m |
| Frontier Airlines | 7 | Airbus A321, Airbus A320neo, Airbus A320-100/200 | 26,441 | 2h 44m |
| Delta Air LinesSeasonal or ended | n/a | Airbus A220-100, Airbus A220-300 | 2,853 | 2h 37m |
Airlines are the operating carrier: regional airlines such as SkyWest or Horizon often fly under a larger airline's brand.
ONT to SEA flight schedule
10 flight numbers flew this route in August 2026, 8 of them almost daily. The first usually leaves at 6:02am and the last at 9:20pm. Times are local and can change; check with the airline before you book.
| Flight | Departs | Arrives | Days flown in August 2026 | On time (12 months) |
|---|---|---|---|---|
| AS 607Alaska Airlines | 6:02am | 8:44am | 31 | 94% |
| DL 3816Delta Air Lines · operated by SkyWest Airlines | 6:20am | 9:17am | 31 | 94% |
| DL 4070Delta Air Lines · operated by SkyWest Airlines | 11:56am | 2:50pm | 26 | 90% |
| AS 654Alaska Airlines | 12:04pm | 2:44pm | 31 | 87% |
| AS 567Alaska Airlines | 2:05pm | 4:45pm | 18 | 80% |
| F9 2275Frontier Airlines | 4:49pm | 7:38pm | 27 | 76% |
| F9 3164Frontier Airlines | 5:17pm | 8:02pm | 4 | 79% |
| AS 575Alaska Airlines | 5:26pm | 8:06pm | 27 | 61% |
| DL 4031Delta Air Lines · operated by SkyWest Airlines | 6:01pm | 8:50pm | 31 | 89% |
| AS 594Alaska Airlines | 9:20pm | 11:59pm | 22 | 66% |
Is ONT to SEA on time?
From September 2025 to August 2026, 86% of 2,488 flights arrived within 15 minutes of schedule and 1.1% were cancelled. Flights leaving around 6am were the most punctual (94%), those around 7pm the least (68%). Most delay time was caused by the airline (crew, maintenance, cleaning, fuelling) (51%).
| Airline | Flights | On time | Average delay | Cancelled |
|---|---|---|---|---|
| Alaska Airlines | 1,258 | 82% | 11 min | 1.7% |
| Delta Air Lines | 1,061 | 92% | 9 min | 0.3% |
| Frontier Airlines | 169 | 77% | 19 min | 1.8% |
Airlines as sold: flights operated by regional partners count under the airline on the ticket. Average delay is across all completed flights, early arrivals counted as zero.
On-time arrivals by departure time
| Scheduled departure | Flights | On time, relative | On time |
|---|---|---|---|
| 6am to 7am | 593 | 94% | |
| 7am to 8am | 121 | 94% | |
| 10am to 11am | 94 | 88% | |
| 11am to 12pm | 353 | 92% | |
| 12pm to 1pm | 184 | 83% | |
| 1pm to 2pm | 53 | 79% | |
| 2pm to 3pm | 107 | 85% | |
| 3pm to 4pm | 138 | 88% | |
| 4pm to 5pm | 244 | 77% | |
| 5pm to 6pm | 299 | 83% | |
| 6pm to 7pm | 86 | 80% | |
| 7pm to 8pm | 137 | 68% |
Flights by month
| Month | Flights | Flights, relative | Passengers |
|---|---|---|---|
| August 2025 | 264 | 31,847 | |
| September 2025 | 211 | 23,856 | |
| October 2025 | 198 | 20,457 | |
| November 2025 | 204 | 22,475 | |
| December 2025 | 197 | 22,359 | |
| January 2026 | 159 | 17,459 | |
| February 2026 | 135 | 15,233 | |
| March 2026 | 174 | 18,632 | |
| April 2026 | 199 | 18,621 | |
| May 2026 | 247 | 23,890 | |
| June 2026 | 237 | 26,403 | |
| July 2026 | 254 | 27,689 |
Related
Source: US Department of Transportation, T-100 Segment data, August 2025 to July 2026.