Salt Lake City to Seattle

What the Data Says About SLC to SEA

The Salt Lake City to Seattle corridor (SLC → SEA) covers roughly 689 miles and is served by 21 carriers, based on Bureau of Transportation Statistics reporting. Across 22,741 flights in the dataset, this route posts a 84% on-time rate with an average delay of 59.0 minutes when flights run late. Over the most recent 24 months of BTS data, 8,101 flights were recorded on this pairing — 63 cancelled (0.8%) and 14 diverted (0.2%). Those baseline metrics tell you what to expect before you book.

Having 21 carriers on the route matters: more carriers generally means more daily schedule options, competitive pricing, and redundancy when flights are cancelled. With 22,741 total flights analyzed, the 84% on-time figure is statistically meaningful rather than a small-sample fluke. The 59.0-minute average delay applies only to flights that actually ran late, so it is not the average wait across all departures — the majority of flights on this route depart on time under the BTS definition of a delay (15+ minutes past schedule).

Looking at recent months, Oct 2024 posted the best performance on this corridor at 91% on-time, while Jun 2025 came in at 67% on-time — a 24-point gap between best and worst recent month. For travelers evaluating the SLC to SEA route, the combination of a 84% on-time rate, 59.0-minute average delay, 0.8% recent cancellation rate, and 21 available carriers is the concrete summary of what BTS data shows about reliability on this pairing.