PlainFlights

Route · SEA → PHL · 2020–2025 BTS data

Seattle to Philadelphia

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), SEA to PHL (Seattle to Philadelphia) ranks #2250 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

79.2%
On-time
+0.2 pts
vs US avg
61 min
Delay when late
5,534
Flights
#2250 of 4927
Corpus placement

Cancelled

1.2%

Best Month

Mar 2025 89%

Worst Month

Aug 2024 50%

Distance

2,378 mi

Carriers

3

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Dec 2025 93 18 1 0 AS,AA
Nov 2025 87 13 0 1 AA,AS
Oct 2025 123 16 2 0 AA,AS
Sep 2025 121 24 0 1 AA,AS
Aug 2025 136 38 1 0 AA,AS
Jul 2025 123 38 6 2 AA,AS
Jun 2025 116 40 0 0 AA,AS
May 2025 93 34 0 0 AA,AS
Apr 2025 82 17 0 0 AA,AS
Mar 2025 72 8 0 0 AA,AS
Feb 2025 36 3 0 0 AA,AS
Jan 2025 38 4 0 0 AA,AS
Dec 2024 86 21 0 0 AA,AS
Nov 2024 74 10 0 0 AS,AA
Oct 2024 77 22 0 0 AS,AA
Sep 2024 91 37 0 0 AA,AS
Aug 2024 124 62 6 2 AA,AS
Jul 2024 123 56 1 1 AA,AS
Jun 2024 116 42 2 0 AA,AS
May 2024 93 24 0 0 AA,AS
Apr 2024 85 19 0 0 AA,AS
Mar 2024 73 14 0 1 AA,AS
Feb 2024 54 11 0 0 AA,AS
Jan 2024 59 21 8 0 AA,AS

SEA–PHL seasonal on-time pattern

Best: February (87.4%) · weakest: June (71.7%)

70%75%80%85%90% JanFebMarAprMayJunJulAugSepOctNovDec 78.4%

Strongest calendar month

February

87.4% on-time · ~51 flights/mo

Busiest calendar month

August

~116 flights/mo avg

Weakest calendar month

June

71.7% on-time · ~100 flights/mo

Cancellation Rate

1.2%

27 of 2,175 flights

Diversion Rate

0.4%

8 of 2,175 flights

Explore origin & destination

On-time and delay data for the airports this route connects.

SEA - Seattle

Full on-time, delay-cause, and seasonal performance for Seattle, WA.

SEA on-time profile

PHL - Philadelphia

Full on-time, delay-cause, and seasonal performance for Philadelphia, PA.

PHL on-time profile

Compare the two airports

See SEA and PHL side by side on delays, cancellations, and reliability.

Compare SEA vs PHL

Origin-hub reliability standing

Mid-pack among SEA departures

From SEA, this corridor sits with 63 other 75–85% on-time routes out of 89 tracked departures, not the hub's reliability leaders (25 at ≥85%) and not the softest ( 1 below 75%). Destination: Philadelphia · fleet on-time rank #3454 of 4927.

What the Data Says About SEA to PHL

5,534 tracked flights put the SEA to PHL pairing (Seattle to Philadelphia) at a 79.2% on-time rate, squarely in line with the wider network. Delays that do occur run 60.8 minutes on average. Across the 2,378-mile route and its 3 carriers, the trailing 24 months show 1.2% cancelled and 0.4% diverted (2,175 flights sampled).

The monthly split is wide on this route: Mar 2025 posted the strongest performance at 89% on-time, while Aug 2024 came in at just 50% - a 39-point swing worth factoring into travel timing.

On the multi-year calendar, SEA–PHL peaks in February at 87.4% on-time while August carries the heaviest traffic (~116 flights per month) ; the softest month is June at 71.7%, a 15.7-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does SEA to PHL rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, SEA to PHL ranks #2250 of 4927 tracked domestic routes by total flights (most flights = #1). That ordinal matches our busiest-routes listing (total_flights DESC). See /methodology#corpus-placement for the exact sort basis.
How often are flights delayed from SEA to PHL? ▼
Flights from Seattle to Philadelphia have a 79.2% on-time rate based on 5,534 flights. The average delay is 60.8 minutes. The best recent month was Mar 2025 with 89% on-time.
What is the cancellation rate for SEA to PHL? ▼
Over the last 24 months, 1.2% of flights on this route were cancelled (27 of 2,175 flights) and 0.4% were diverted.
How far is the flight from SEA to PHL? ▼
The flight distance from Seattle (SEA) to Philadelphia (PHL) is approximately 2,378 miles. This route is served by 3 carriers.
When is the best time to fly from SEA to PHL? ▼
The best recent month for on-time performance was Mar 2025 (89% on-time). The worst was Aug 2024 (50% on-time). Consider booking during months with historically better performance.

Airports on this route

SEA Airport

Seattle
PHL Airport

Philadelphia
Data source

Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data. Statistics reflect cumulative performance across all available reporting periods.

Read our methodology - how this data is sourced, computed, and verified.

Using SEA–PHL data

SEA–PHL is mid-pack at 79.2% on-time; month and carrier mix move more than the corridor headline.

  • Compare SEA and PHL airport profiles: delay causes and top routes differ even on the same corridor. SEA airport
  • If your dates flex, February (87.4% on-time) beats June (71.7%) on this corridor. Seasonal chart
  • 4 other routes post a similar 79.2% on-time rate; compare before you commit to this pairing. Similar routes

On-time rate reflects the BTS historical average across all reporting carriers on this origin–destination pair, not any single flight or booking recommendation.

Data sourced from U.S. Department of Transportation Bureau of Transportation Statistics (BTS) On-Time Performance data. See our methodology for details. Retrieved and formatted by PlainFlights

Every figure on PlainFlights is rendered directly from BTS On-Time Performance data, no number is typed in by an editor. This page aggregates this specific route's on-time performance and monthly trend, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.