Salt Lake City (SLC) to Seattle (SEA): On-Time Performance
Data through July 2026
The calendar drives reliability on SLC–SEA. October 2024 flights landed on schedule 91% of the time, but June 2025 dropped to 67% — a gap of 24 points. Across the full period the route averages 80% on-time against a national 78%. Morning departures also hold up better than evening ones (85% vs 74%), which matters most in the rough months.
- On-time
- 80%
- arrived <15 min late
- Avg delay
- 11 min
- completed flights
- Cancelled
- 0.7%
- Flights/day
- 11
- last 12 months
- Duration
- 2h 20m
- scheduled
- Distance
- 689 mi
Best airline from SLC to SEA
4 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| Delta Air Linesmost reliable | 84% | 9 min | 0.5% | 4,715 |
| SkyWest Airlines | 75% | 15 min | 0.0% | 956 |
| Frontier Airlines | 74% | 19 min | 2.1% | 192 |
| Alaska Airlines | 74% | 13 min | 1.4% | 2,705 |
Monthly on-time trend
Best time to fly from SLC to SEA
Aim for departures around 11 p.m. (95% on-time); avoid 9 a.m. departures (55%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 80% | 12 min |
| Tuesdaybest | 84% | 10 min |
| Wednesday | 83% | 10 min |
| Thursday | 78% | 12 min |
| Friday | 78% | 12 min |
| Saturday | 81% | 11 min |
| Sunday | 77% | 14 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft32%
- Airline operations40%
- National airspace system23%
- Weather5%
Frequently asked questions
- How often are flights from SLC to SEA delayed?
- 20% of SLC–SEA flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-07 and 2026-07. The average arrival delay across completed flights was 11 minutes.
- Which airline is most reliable from SLC to SEA?
- Delta Air Lines has the best on-time record on this route at 84%, based on 4,715 flights. 4 airlines flew SLC–SEA frequently enough to compare in this period.
- What is the best time of day to fly from SLC to SEA?
- Departures around 11 p.m. have the best record (95% on-time), while departures around 9 a.m. have the worst (55%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from SLC to SEA?
- The scheduled SLC–SEA flight time averages 2h 20m over 689 miles. Actual arrival times vary — flights on this route land 15+ minutes late 20% of the time.
- How often are SLC to SEA flights cancelled?
- 0.7% of scheduled flights on this route were cancelled between 2024-07 and 2026-07, at or below the national rate of 1.6%.
- What is the worst month to fly from SLC to SEA?
- June 2025 was the roughest month in this dataset, with only 67% of arrivals on time. The best was October 2024 at 91%. If your dates are flexible, that 24-point gap is worth planning around.
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Based on 8,568 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.