Flight Check

Best Airline: SEA to DEN

Seattle to Denver — airline reliability comparison

United Airlines is the most reliable airline on the SEA to DEN route with a 87% on-time rate, compared to Frontier Airlines at 68%. Based on 7,003 flights tracked.

This route involves weather-prone airports and high-congestion airports, which can affect reliability regardless of airline.

Source: Bureau of Transportation Statistics. Updated October 2026.

On-Time Rate by Airline

United Airlines87%
SkyWest Airlines83%
Delta Air Lines77%
Alaska Airlines76%
Southwest Airlines75%
Frontier Airlines68%

SEA to DEN Airline Comparison

AirlineOn-Time %Cancel %Avg DelayFlights
United AirlinesUABest87%1.0%77m7,003
SkyWest AirlinesOO83%0.3%57m479
Delta Air LinesDL77%0.7%67m3,413
Alaska AirlinesAS76%0.8%48m5,640
Southwest AirlinesWN75%0.6%52m5,246
Frontier AirlinesF9Worst68%1.4%69m1,591

Route Overview

78%
Overall On-Time
60m
Avg Delay
0.8%
Cancel Rate
23,392
Total Flights
SEA to DEN Route DetailsReturn: DEN to SEA
SEA AirportDEN Airport

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Data last updated October 2026. Source: Bureau of Transportation Statistics.