Alaska Airlines is the most reliable airline on the STL to SEA route with a 84% on-time rate, compared to Southwest Airlines at 62%. Based on 2,782 flights tracked.
Source: Bureau of Transportation Statistics. Updated October 2026.Best Airline: STL to SEA
St. Louis to Seattle — airline reliability comparison
On-Time Rate by Airline
Alaska Airlines84%
Southwest Airlines62%
STL to SEA Airline Comparison
| Airline | On-Time % | Cancel % | Avg Delay | Flights |
|---|---|---|---|---|
| Alaska AirlinesASBest | 84% | 1.1% | 59m | 2,782 |
| Southwest AirlinesWNWorst | 62% | 0.0% | 43m | 263 |
Route Overview
82%
Overall On-Time
55m
Avg Delay
0.8%
Cancel Rate
3,062
Total Flights
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Data last updated October 2026. Source: Bureau of Transportation Statistics.