SEA to IAD flight delays & on-time performance
Nonstop flights from Seattle–Tacoma International Airport to Washington Dulles International Airport · 2,305 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at SEA or IAD right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from Seattle (SEA) to Washington (IAD) arrived on time 83% of the time in Aug 2025 – Jul 2026, better than the 78% national average.
- 0.6% were cancelled, and 5% arrived an hour or more late.
- United Airlines was the most punctual airline here (89% on time); Delta Air Lines was the least (76%).
- Departures scheduled around 8am did best (90% on time); around 3pm did worst (76%).
- Wednesday was the most reliable day to fly (89% on time) and Saturday the least (81%).
- The largest source of delay minutes was airline (crew, maintenance, cleaning, fueling) (49%).
Which airline is most on time from SEA to IAD?
Ranked by on-time arrival rate. Regional airlines fly under their partner's brand (e.g. SkyWest for Delta Connection or United Express).
| Airline | On time | Cancelled | Avg delay | 1 hr+ late | Flights |
|---|---|---|---|---|---|
| United Airlines | 89% | 0.8% | 10 min | 4.3% | 657 |
| Alaska Airlines | 82% | 0.4% | 8 min | 2.2% | 835 |
| Delta Air Lines | 76% | 1.1% | 19 min | 10.7% | 361 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 8am90%467 flights
- 9am82%185 flights
- 10am86%74 flights
- 1pm88%131 flights
- 3pm76%220 flights
- 4pm79%261 flights
- 9pm81%135 flights
- 10pm79%180 flights
- 11pm84%197 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday83%0.0% cancelled
- Tuesday84%0.4% cancelled
- Wednesday89%0.0% cancelled
- Thursday84%0.7% cancelled
- Friday82%1.0% cancelled
- Saturday81%0.4% cancelled
- Sunday82%1.8% cancelled
On-time trend by month
Why flights are late
Share of delay minutes by cause, as reported by airlines to the DOT.
- Airline (crew, maintenance, cleaning, fueling)49%
- Late-arriving aircraft33%
- Air traffic control & airport congestion14%
- Extreme weather4%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Extreme weather75%
- Airline (crew, maintenance, cleaning, fueling)25%
- Air traffic control & airport congestion0%
- Security0%
SEA to IAD: common questions
- How often are SEA to IAD flights on time?
- 83% of flights arrived less than 15 minutes late in Aug 2025 – Jul 2026, compared with 78% for all US flights.
- How often are flights from Seattle to Washington cancelled?
- 0.6% of scheduled flights were cancelled (12 of 1,853).
- How long are typical delays?
- Across all flights the average arrival delay was 11 min (early arrivals count as zero). Flights that were late arrived 59 min behind schedule on average, and 4.6% of flights were an hour or more late.
- How long is taxi time at SEA?
- Flights on this route spent 21 min taxiing from the gate to takeoff on average.
Related routes
Return trip: IAD to SEA — 78% on time
More flights from Seattle
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: SEA → IAD, nonstop flights by US airlines that report to the DOT. How we calculate this.