Seattle (SEA) to Washington (IAD): On-Time Performance
Data through May 2026
When you fly SEA to IAD matters as much as anything else about the booking: the route swung from 89% on-time in November 2024 to just 69% in July 2025. Across the full period the route averages 81% on-time against a national 78%.
- On-time
- 81%
- arrived <15 min late
- Avg delay
- 12 min
- completed flights
- Cancelled
- 0.7%
- Flights/day
- 5.3
- last 12 months
- Duration
- 5h 1m
- scheduled
- Distance
- 2,305 mi
Best airline from SEA to IAD
3 airlines flew this route regularly between 2024-06 and 2026-05.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| United Airlinesmost reliable | 85% | 11 min | 1.3% | 1,578 |
| Delta Air Lines | 81% | 15 min | 0.7% | 895 |
| Alaska Airlines | 78% | 10 min | 0.2% | 1,678 |
Monthly on-time trend
Best time to fly from SEA to IAD
Aim for departures around 12 p.m. (89% on-time); avoid 3 p.m. departures (72%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 82% | 12 min |
| Tuesday | 83% | 12 min |
| Wednesdaybest | 85% | 9 min |
| Thursday | 82% | 11 min |
| Friday | 80% | 11 min |
| Saturday | 81% | 12 min |
| Sunday | 78% | 14 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft35%
- Airline operations46%
- National airspace system16%
- Weather3%
Frequently asked questions
- How often are flights from SEA to IAD delayed?
- 19% of SEA–IAD flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-06 and 2026-05. The average arrival delay across completed flights was 12 minutes.
- Which airline is most reliable from SEA to IAD?
- United Airlines has the best on-time record on this route at 85%, based on 1,578 flights. 3 airlines flew SEA–IAD frequently enough to compare in this period.
- What is the best time of day to fly from SEA to IAD?
- Departures around 12 p.m. have the best record (89% on-time), while departures around 3 p.m. have the worst (72%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from SEA to IAD?
- The scheduled SEA–IAD flight time averages 5h 1m over 2,305 miles. Actual arrival times vary — flights on this route land 15+ minutes late 19% of the time.
- How often are SEA to IAD flights cancelled?
- 0.7% of scheduled flights on this route were cancelled between 2024-06 and 2026-05, at or below the national rate of 1.6%.
- What is the worst month to fly from SEA to IAD?
- July 2025 was the roughest month in this dataset, with only 69% of arrivals on time. The best was November 2024 at 89%. If your dates are flexible, that 20-point gap is worth planning around.
Explore related pages
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Based on 4,151 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.