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Route Reliability

Washington → Seattle

IAD–SEA · 2,305 miles · Washington Dulles International Airport to Seattle–Tacoma International Airport

80
Pretty Reliable
WanderNerd Reliability Score
77%
Arrive within 15 minutes
7 min
Average arrival delay
1.0%
Cancelled
1,926
Flights in the data

Data through May 2026.

Who flies it best

Ranked by on-time arrivals. Historical results, not predictions.

  1. 1.United Airlines80%730 flights
  2. 2.Delta Air Lines79%361 flights
  3. 3.Alaska Airlines73%835 flights

What the data says

The 12–3 PM departure wins.

IAD–SEA flights departing between 12–3 PM arrived on time 93% of the time, versus 59% between 6–9 PM.

Wednesday comes out ahead.

A small edge: 79% on time on Wednesdays against 74% on Sundays.

United Airlines has a slight edge here.

United Airlines arrived on time 80% of the time on this route; Alaska Airlines managed 73%.

Trending in the right direction.

IAD–SEA flights arrived on time 76% of the time over the last three months in the data, compared with 67% in the three months before that.

Best historical flights

Ranked by on-time arrivals, minimum 100 flights. Past performance, not a promise.

Top flights by on-time rate

More flights on this route

The breakdown

On-time by weekday
  • Mon76%(282 flights)
  • Tue76%(258 flights)
  • Wed79%(258 flights)
  • Thu79%(280 flights)
  • Fri76%(280 flights)
  • Sat78%(262 flights)
  • Sun74%(282 flights)
On-time by departure window
  • 6–9 AM81%(744 flights)
  • 9 AM–12 PM81%(242 flights)
  • 12–3 PM93%(165 flights)
  • 3–6 PM74%(377 flights)
  • 6–9 PM59%(298 flights)
  • 9 PM–12 AM70%(76 flights)
On-time trend by month
87%
May

Jun 73% → May 87% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202573%236
July 202574%242
August 202581%220
September 202593%179
October 202585%154
November 202570%116
December 202550%122
January 202675%100
February 202676%91
March 202657%114
April 202683%127
May 202687%201

Same trip, other airports

Keep nerding

Based on 1,926 historical flights, because apparently we checked. Historical flight data: U.S. Bureau of Transportation Statistics, June 2025 – May 2026. Data through May 2026. How we calculate this.