OnTimeStats

Historical on-time performance

Seattle to Philadelphia

2,378 miData through May 2026Source: US DOT · BTS

Flights on SEA–PHL arrive on time 78% of the time over the last 12 months.

On-time rate78%arrived within 15 min
p90 delay30 min1 in 10 flights is worse (tail risk)
Cancelled1.4%of scheduled flights

based on 1,160 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

By airline

How each carrier compares

Too close to call — no single carrier is clearly more on-time here.

  • American Airlines
    On-time80%
    Medianon time
    p9030 min
    Cancel1.7%
    Flights532
  • Alaska Airlines
    On-time76%
    Medianon time
    p9035 min
    Cancel1.1%
    Flights628

Why flights run late

Delay causes

  • Airline31%
  • Weather13%
  • Air traffic (NAS)18%
  • Late aircraft38%
  • Security0%

Most delay minutes here are attributed to Late aircraft.

When flights don't go

Why flights were cancelled

  • Airline31%
  • Weather69%
  • Air traffic (NAS)0%
  • Security0%

Most cancellations here are attributed to Weather. Shares are among 16 cancellations with a reported cause (BTS reports causes from June 2003).

Over time

On-time trend

By season

On-time rate by month

When to fly

Best time to fly SEA → PHL

All airlines · rolling 36 months (2023-06 .. 2026-05).

Best time of day

On-time rates are fairly even by time of day on this route — ranging from 72% to 75% on time.

  • Overnights75% on time · p90 35 min · 1,781 flights
  • Mornings73% on time · p90 30 min · 1,209 flights
  • Middays72% on time · p90 45 min · 384 flights

Best day of week

On-time rates are fairly even by day on this route — ranging from 70% to 79% on time.

  • Wednesdays79% on time · p90 25 min · 476 flights
  • Tuesdays78% on time · p90 25 min · 457 flights
  • Saturdays74% on time · p90 30 min · 467 flights
  • Thursdays73% on time · p90 35 min · 493 flights
  • Mondays72% on time · p90 35 min · 488 flights
  • Fridays71% on time · p90 45 min · 499 flights
  • Sundays70% on time · p90 40 min · 498 flights

Keep exploring

Related pages

Methodology

A flight is on time when it arrives within 15 minutes of schedule — the US DOT / BTS standard. Median and p90(the “1-in-10 bad day”) are read from the full arrival-delay distribution, never averaged across periods.

Figures cover a carrier’s own BTS-coded flights. Cells below ~200 flights are flagged as limited data. All numbers are pre-computed from public BTS On-Time Performance data.