Route on-time record
SEA to PHL: most on-time flights and the best time to fly
Seattle (Seattle–Tacoma International Airport) to Philadelphia (Philadelphia International Airport). 1,269 nonstop flights in Jun 2025 to May 2026, 80% arrived within 15 minutes and 1.4% were cancelled. The most reliable flight number was American 872 at 12:34 PM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
SEA → PHL
Seattle to Philadelphia: 1,269 nonstop flights a year
On time (12 months)
80%
Cancelled
1.4%
avg delay 12 min
Best time to leave
Before 9 AM
86% on time vs 72% 9 AM to noon
Most reliable airline
American
81% chance on time
Fares open on our travel partner (Aviasales). Pick the flight number you chose here.
Most reliable nonstop flights
Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.
#1 · American 872
12:34 PM → 8:55 PM5h 21m nonstop
Local times, typical schedule. Last flown 2026-05-20.
87%
chance on time
- On time (history)
- 95%
- Cancelled
- 0.0%
- Avg arrival delay
- 2 min
- Arrived on time 95% of the time (44 flights, Jun 2025 to May 2026).
- Never cancelled in 44 scheduled flights.
- Departs outside SEA's trouble window (4 PM to 10 PM, when 54% of its 68 ground stops and delay programs started).
Limited track record · 44 flights
Find American 872 fares Opens this date on Aviasales#2 · American 2763
10:47 PM → 7:00 AM5h 13m nonstop
Local times, typical schedule. Last flown 2026-05-20.
87%
chance on time
- On time (history)
- 93%
- Cancelled
- 0.0%
- Avg arrival delay
- 4 min
- Arrived on time 93% of the time (44 flights, Jun 2025 to May 2026).
- Never cancelled in 44 scheduled flights.
- Departs outside SEA's trouble window (4 PM to 10 PM, when 54% of its 68 ground stops and delay programs started).
Limited track record · 44 flights
Find American 2763 fares Opens this date on Aviasales#3 · Alaska 371
9:55 PM → 6:05 AM5h 13m nonstop
Local times, typical schedule. Last flown 2026-05-31.
85%
chance on time
- On time (history)
- 89%
- Cancelled
- 0.0%
- Avg arrival delay
- 5 min
- Arrived on time 89% of the time (145 flights, Jun 2025 to May 2026).
- Never cancelled in 145 scheduled flights.
- Departs inside SEA's trouble window: 54% of its 68 ground stops and delay programs started between 4 PM and 10 PM.
Moderate track record · 145 flights
Find Alaska 371 fares Opens this date on Aviasales#4 · American 2522
10:35 PM → 6:47 AM5h 12m nonstop
Local times, typical schedule. Last flown 2026-05-31.
85%
chance on time
- On time (history)
- 91%
- Cancelled
- 0.0%
- Avg arrival delay
- 3 min
- Arrived on time 91% of the time (11 flights, Jun 2025 to May 2026).
- Departs outside SEA's trouble window (4 PM to 10 PM, when 54% of its 68 ground stops and delay programs started).
Limited track record · 11 flights
Find American 2522 fares Opens this date on Aviasales#5 · American 2534
12:46 PM → 9:08 PM5h 22m nonstop
Local times, typical schedule. Last flown 2026-05-31.
82%
chance on time
- On time (history)
- 89%
- Cancelled
- 0.0%
- Avg arrival delay
- 2 min
- Arrived on time 89% of the time (9 flights, Jun 2025 to May 2026).
- Departs outside SEA's trouble window (4 PM to 10 PM, when 54% of its 68 ground stops and delay programs started).
Limited track record · 9 flights
Find American 2534 fares Opens this date on Aviasales#6 · American 3219
8:10 AM → 4:34 PM5h 24m nonstop
Local times, typical schedule. Last flown 2026-05-31.
81%
chance on time
- On time (history)
- 82%
- Cancelled
- 0.0%
- Avg arrival delay
- 6 min
- Arrived on time 82% of the time (11 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 86% on time; 9 AM to noon: 72%).
- Departs outside SEA's trouble window (4 PM to 10 PM, when 54% of its 68 ground stops and delay programs started).
- Lands inside PHL's trouble window: 72% of its 95 ground stops and delay programs started between 2 PM and 8 PM.
Limited track record · 11 flights
Find American 3219 fares Opens this date on Aviasales#7 · Delta 1114
9:20 PM → 5:37 AM5h 17m nonstop
Local times, typical schedule. Last flown 2026-05-31.
77%
chance on time
- On time (history)
- 72%
- Cancelled
- 0.0%
- Avg arrival delay
- 11 min
- Arrived on time 72% of the time (25 flights, Jun 2025 to May 2026).
- Departs inside SEA's trouble window: 54% of its 68 ground stops and delay programs started between 4 PM and 10 PM.
Limited track record · 25 flights
Find Delta 1114 fares Opens this date on Aviasales#8 · Alaska 442
9:37 AM → 5:47 PM5h 10m nonstop
Local times, typical schedule. Last flown 2026-05-31.
71%
chance on time
- On time (history)
- 72%
- Cancelled
- 1.1%
- Avg arrival delay
- 14 min
- Arrived on time 72% of the time (358 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (9 AM to noon: 72% on time; Before 9 AM: 86%).
- Departs outside SEA's trouble window (4 PM to 10 PM, when 54% of its 68 ground stops and delay programs started).
- Lands inside PHL's trouble window: 72% of its 95 ground stops and delay programs started between 2 PM and 8 PM.
Strong track record · 358 flights
Find Alaska 442 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- American Airlines81%
588 flights · 82% on time as flown · 1.8% cancel
- Alaska Airlines77%
656 flights · 77% on time as flown · 1.1% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM86%
80 flights · avg delay 40 min
- 9 AM to noon72%
364 flights · avg delay 14 min
- Noon to 3 PM80%
168 flights · avg delay 12 min
- After 9 PM83%
657 flights · avg delay 9 min
Best day: Wednesday (80%). Worst: Friday (72%).
On time by month
All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.
What delays this route
- Late-arriving aircraft37%
- Airline (crew, maintenance, boarding)34%
- Air traffic control and airport volume18%
- Severe weather12%
Share of delay minutes by the cause airlines report to the US DOT.
Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure
SEA to PHL questions
- What time of day is best to fly SEA to PHL?
- Before 9 AM: 86% of flights arrived on time, against 72% for departures 9 AM to noon. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
- Which airline is most on time from SEA to PHL?
- American, with a season-adjusted 81% chance of operating and arriving on time over 588 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
- What is the worst month for delays on SEA to PHL?
- July (65% on time); the best was February (85%), averaged over Jun 2023 to May 2026.
- Is this a prediction for my flight?
- No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.
More routes from SEA
- PHL to SEA (return)
- SEA to LAX 83%
- SEA to PHX 79%
- SEA to SFO 69%
- SEA to ANC 74%
- SEA to DEN 77%
- SEA to LAS 77%
- SEA to ORD 75%
- SEA to GEG 81%
- SEA to DFW 77%
- SEA to PDX 82%
- SEA to SAN 78%
- SEA to SMF 81%
Most on-time flights from SEA on every route →
Live status: FAA delays and ground stops