Seattle to Salt Lake City

What the Data Says About SEA to SLC

The Seattle to Salt Lake City corridor (SEA → SLC) covers roughly 689 miles and is served by 22 carriers, based on Bureau of Transportation Statistics reporting. Across 22,743 flights in the dataset, this route posts a 85.1% on-time rate with an average delay of 58.4 minutes when flights run late. Over the most recent 24 months of BTS data, 8,096 flights were recorded on this pairing — 61 cancelled (0.8%) and 2 diverted (0.0%). Those baseline metrics tell you what to expect before you book.

Having 22 carriers on the route matters: more carriers generally means more daily schedule options, competitive pricing, and redundancy when flights are cancelled. With 22,743 total flights analyzed, the 85.1% on-time figure is statistically meaningful rather than a small-sample fluke. The 58.4-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, Jan 2025 posted the best performance on this corridor at 90% on-time, while Jul 2024 came in at 76% on-time — a 14-point gap between best and worst recent month. For travelers evaluating the SEA to SLC route, the combination of a 85.1% on-time rate, 58.4-minute average delay, 0.8% recent cancellation rate, and 22 available carriers is the concrete summary of what BTS data shows about reliability on this pairing.