Route profile
SEA→IAD
Flight reliability, delays and best times to fly from Seattle to Washington, 2,306 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 73% of comparable major US routes (4,598 compared)
Calculated from 6,525 flights. How this is calculated · What counts as on time
SEA → IAD arrives on time 81.3% of the time; the return trip, IAD → SEA, arrives on time 79.4% of the time.
SEA → IAD spends 29.1 minutes on the ground on a 2,306-mile trip: 21.8 minutes from pushback to wheels-up at SEA and 7.2 minutes from touchdown to gate at IAD.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What sets this route apart
Where SEA to IAD differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
SEA to IAD is at its best against routes of similar length for flights scheduled at 1 PM: 86.8% arrive on time, 11.3 points ahead of the 75.5% those routes manage at that hour. Against all other routes the gap is 9.7 points.
SEA to IAD struggles most at 10 PM: 77.6% of its flights scheduled then arrive on time, 3.9 points behind the 81.5% on routes of similar length at the same hour.
SEA to IAD holds up on Wednesdays better than routes of similar length do: 85.4% on time to their 80.7%, a 4.7 points lead. Against all other routes the gap is 4.6 points.
July is kinder to SEA to IAD than to routes of similar length: 76.4% on time against 70.4%, 6 points better. Against all other routes the gap is 6.7 points.
United Airlines does better on SEA to IAD than on its routes of similar length: 85.3% on time here, 81.2% there, 4.1 points apart. Against all other routes the gap is 5.4 points.
SEA to IAD against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 1 PM departures | 86.8% | routes of similar length | 75.5% | +11.3 pts | 325 here, 56,000 there |
| Hour: 10 PM departures | 77.6% | routes of similar length | 81.5% | −3.9 pts | 653 here, 66,788 there |
| Weekday: Wednesday | 85.4% | routes of similar length | 80.7% | +4.7 pts | 906 here, 158,631 there |
| Month: July | 76.4% | routes of similar length | 70.4% | +6.0 pts | 974 here, 135,458 there |
| Airline: United Airlines | 85.3% | routes of similar length | 81.2% | +4.1 pts | 2,367 here, 240,032 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 2,306 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
Why SEA → IAD flights are cancelled
July 2023 – July 2026
SEA → IAD cancelled 72 of 6,525 scheduled flights — about 1 in every 91. The reason filed most often was the airline, 75.0% of the cancellations coded on this route — about 1 in every 121 scheduled flights.
Share of cancellations
Of 72 cancelled departures carrying a reason code.
What each reason means
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
54 cancellations, 75.0% of the total.
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
18 cancellations, 25.0% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
0 cancellations, 0.0% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
72 coded cancellations were recorded on SEA → IAD; the section appears from 50.
When it goes wrong
July 2023 – July 2026
31 min late
against a median of 6 min early
Percentiles over 6,525 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at IAD after arriving from SEA.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 36% | Likely to miss |
| 45 min | 18% | High risk |
| 60 min | 10% | Some risk |
| 90 min | 5.0% | Some risk |
| 120 min | 2.9% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.10% of the time and diverts 0.43% of the time, which a late arrival never shows up in.
Chance of missing is the share of 6,425 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 31 minutes late (90th-percentile gate arrival delay), over 6,525 operations.
Any other layover length: connection checker.
Best time to fly
SEA → IAD flights departing 12–3 PM arrived on time 86.7% of the time, against 77.3% for 9 AM–12 PM departures, a gap of 9.4 percentage points.
By departure window
By departure hour
- 12 AM to 6 AM: too few flights to score
- 7 AM: 85.4% on time from 212 flights
- 8 AM: 85.6% on time from 1,634 flights
- 9 AM: 78.9% on time from 513 flights
- 10 AM: 75.6% on time from 515 flights
- 11 AM: too few flights to score
- 12 PM: 86.7% on time from 342 flights
- 1 PM: 86.8% on time from 328 flights
- 2 PM: too few flights to score
- 3 PM: 74.9% on time from 355 flights
- 4 PM: 78.7% on time from 675 flights
- 5 PM to 8 PM: too few flights to score
- 9 PM: 77.6% on time from 437 flights
- 10 PM: 77.6% on time from 667 flights
- 11 PM: 82.2% on time from 838 flights
Why SEA → IAD runs late
July 2023 – July 2026
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for SEA → IAD. Only delays of 15 minutes or more are attributed. What the five causes mean
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Alaska Airlines | 2,624 | 78.7% | 0.46% | -3 min | 3.3% |
| United Airlines | 2,426 | 85.3% | 1.94% | -9 min | 5.4% |
| Delta Air Lines | 1,475 | 79.6% | 0.88% | -7 min | 7.8% |
Alaska Airlines flew 40.2% of the 6,525 flights listed. United Airlines cancelled 1.94% of its flights here against 0.46% for Alaska Airlines.
United Airlines arrived on time 6.6 percentage points more often than Alaska Airlines on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Sunday the least, a gap of 7.3 percentage points.
By month
- Jan: 79.3%
- Feb: 84.0%
- Mar: 79.7%
- Apr: 84.1%
- May: 79.4%
- Jun: 80.2%
- Jul: 76.4%
- Aug: 80.1%
- Sep: 82.6%
- Oct: 88.0%
- Nov: 84.4%
- Dec: 83.4%
July is historically the weakest month and October the strongest, a spread of 11.6 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 77.4% from 257 flights
- August 2023: 84.2% from 280 flights
- September 2023: 76.6% from 240 flights
- October 2023: 89.5% from 221 flights
- November 2023: 78.3% from 143 flights
- December 2023: 76.6% from 129 flights
- January 2024: too few flights to score (104)
- February 2024: too few flights to score (96)
- March 2024: too few flights to score (119)
- April 2024: 83.0% from 147 flights
- May 2024: 77.4% from 228 flights
- June 2024: 81.3% from 270 flights
- July 2024: 78.5% from 278 flights
- August 2024: 82.7% from 264 flights
- September 2024: 84.7% from 231 flights
- October 2024: 88.7% from 194 flights
- November 2024: 88.9% from 180 flights
- December 2024: 85.8% from 135 flights
- January 2025: too few flights to score (103)
- February 2025: too few flights to score (94)
- March 2025: too few flights to score (116)
- April 2025: 81.3% from 155 flights
- May 2025: 75.0% from 203 flights
- June 2025: 76.5% from 240 flights
- July 2025: 69.4% from 245 flights
- August 2025: 71.9% from 222 flights
- September 2025: 87.6% from 179 flights
- October 2025: 85.0% from 155 flights
- November 2025: too few flights to score (119)
- December 2025: 87.9% from 124 flights
- January 2026: too few flights to score (102)
- February 2026: too few flights to score (94)
- March 2026: too few flights to score (117)
- April 2026: 89.0% from 129 flights
- May 2026: 86.0% from 202 flights
- June 2026: 83.2% from 198 flights
- July 2026: 80.5% from 212 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 83.4% against 80.9% in the 12 months before — improving by 2.5 percentage points.
Data and methodology
Calculated by FlyerIntel from 6,525 SEA → IAD flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed