Philadelphia (PHL) to Seattle (SEA): On-Time Performance
Data through July 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 68% on-time against a national 78%. Morning departures also hold up better than evening ones (78% vs 61%), which matters most in the rough months.
- On-time
- 68%
- arrived <15 min late
- Avg delay
- 20 min
- completed flights
- Cancelled
- 1.7%
- Flights/day
- 3.8
- last 12 months
- Duration
- 6h 8m
- scheduled
- Distance
- 2,379 mi
Best airline from PHL to SEA
3 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| Delta Air Linesmost reliable | 68% | 26 min | 0.0% | 82 |
| American Airlines | 68% | 20 min | 2.3% | 1,084 |
| Alaska Airlines | 68% | 18 min | 1.3% | 1,357 |
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 (60%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 67% | 17 min |
| Tuesdaybest | 75% | 18 min |
| Wednesday | 71% | 15 min |
| Thursday | 64% | 23 min |
| Friday | 65% | 22 min |
| Saturday | 69% | 18 min |
| Sunday | 66% | 23 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft27%
- Airline operations32%
- National airspace system37%
- Weather4%
Frequently asked questions
- How often are flights from PHL to SEA delayed?
- 32% of PHL–SEA flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-07 and 2026-07. The average arrival delay across completed flights was 20 minutes.
- Which airline is most reliable from PHL to SEA?
- Delta Air Lines has the best on-time record on this route at 68%, based on 82 flights. 3 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 (60%). 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 8m over 2,379 miles. Actual arrival times vary — flights on this route land 15+ minutes late 32% of the time.
- How often are PHL to SEA flights cancelled?
- 1.7% of scheduled flights on this route were cancelled between 2024-07 and 2026-07, slightly above 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 2,523 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.