United Airlines is the most reliable airline on the SEA to IAD route with a 87% on-time rate, compared to Delta Air Lines at 79%. Based on 2,820 flights tracked.
Source: Bureau of Transportation Statistics. Updated October 2026.Best Airline: SEA to IAD
Seattle to Washington — airline reliability comparison
On-Time Rate by Airline
United Airlines87%
Alaska Airlines80%
Delta Air Lines79%
SEA to IAD Airline Comparison
| Airline | On-Time % | Cancel % | Avg Delay | Flights |
|---|---|---|---|---|
| United AirlinesUABest | 87% | 2.1% | 66m | 2,820 |
| Alaska AirlinesAS | 80% | 0.7% | 41m | 3,010 |
| Delta Air LinesDLWorst | 79% | 0.9% | 78m | 1,676 |
Route Overview
82%
Overall On-Time
60m
Avg Delay
1.1%
Cancel Rate
7,506
Total Flights
Flying out of SEA? We'll brief you.
Delays, TSA, weather, gates — we'll let you know if something matters.
Data last updated October 2026. Source: Bureau of Transportation Statistics.