Philadelphia (PHL) to Seattle (SEA): On-Time Performance
Data through May 2026
When you fly PHL to SEA matters as much as anything else about the booking: the route swung from 87% on-time in February 2026 to just 38% in December 2025. Across the full period the route averages 67% on-time against a national 78%. Morning departures also hold up better than evening ones (77% vs 60%), which matters most in the rough months.
- On-time
- 67%
- arrived <15 min late
- Avg delay
- 20 min
- completed flights
- Cancelled
- 1.5%
- Flights/day
- 3.5
- last 12 months
- Duration
- 6h 7m
- scheduled
- Distance
- 2,379 mi
Best airline from PHL to SEA
2 airlines flew this route regularly between 2024-06 and 2026-05.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| American Airlinesmost reliable | 68% | 21 min | 2.2% | 962 |
| Alaska Airlines | 66% | 19 min | 1.0% | 1,295 |
Monthly on-time trend
Best time to fly from PHL to SEA
Aim for departures around 9 a.m. (94% on-time); avoid 7 p.m. departures (57%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 66% | 18 min |
| Tuesdaybest | 75% | 17 min |
| Wednesday | 67% | 17 min |
| Thursday | 64% | 23 min |
| Friday | 63% | 23 min |
| Saturday | 69% | 18 min |
| Sunday | 66% | 21 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft28%
- Airline operations33%
- National airspace system36%
- Weather3%
Frequently asked questions
- How often are flights from PHL to SEA delayed?
- 33% of PHL–SEA 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 20 minutes.
- Which airline is most reliable from PHL to SEA?
- American Airlines has the best on-time record on this route at 68%, based on 962 flights. 2 airlines flew PHL–SEA frequently enough to compare in this period.
- What is the best time of day to fly from PHL to SEA?
- Departures around 9 a.m. have the best record (94% on-time), while departures around 7 p.m. have the worst (57%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from PHL to SEA?
- The scheduled PHL–SEA flight time averages 6h 7m over 2,379 miles. Actual arrival times vary — flights on this route land 15+ minutes late 33% of the time.
- How often are PHL to SEA flights cancelled?
- 1.5% 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 PHL to SEA?
- December 2025 was the roughest month in this dataset, with only 38% of arrivals on time. The best was February 2026 at 87%. If your dates are flexible, that 49-point gap is worth planning around.
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Based on 2,281 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.