OnTimeStats

Historical on-time performance

Chicago to Seattle

1,733 miData through Dec 2025Source: US DOT · BTS

Flights on MDW–SEA arrive on time 67% of the time over the last 12 months.

On-time rate67%arrived within 15 min
p90 delay45 min1 in 10 flights is worse (tail risk)
Cancelled0.4%of scheduled flights

based on 557 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

By airline

How each carrier compares

  • Southwest Airlines
    On-time67%
    Medianon time
    p9045 min
    Cancel0.4%
    Flights557

Why flights run late

Delay causes

  • Airline33%
  • Weather3%
  • Air traffic (NAS)22%
  • Late aircraft40%
  • Security1%

Most delay minutes here are attributed to Late aircraft.

Over time

On-time trend

By season

On-time rate by month

When to fly

Best time to fly MDW → SEA

All airlines · rolling 36 months (2023-01 .. 2025-12).

Best time of day

On-time rates are fairly even by time of day on this route — ranging from 59% to 78% on time.

  • Middays78% on time · p90 25 min · 402 flights
  • Mornings74% on time · p90 30 min · 409 flights
  • Evenings66% on time · p90 55 min · 169 flights · limited
  • Afternoons61% on time · p90 55 min · 446 flights
  • Overnights59% on time · p90 55 min · 253 flights

Best day of week

On-time rates are fairly even by day on this route — ranging from 63% to 72% on time.

  • Wednesdays72% on time · p90 40 min · 245 flights
  • Tuesdays71% on time · p90 45 min · 245 flights
  • Mondays71% on time · p90 35 min · 247 flights
  • Sundays69% on time · p90 50 min · 227 flights
  • Thursdays67% on time · p90 40 min · 245 flights
  • Fridays64% on time · p90 50 min · 245 flights
  • Saturdays63% on time · p90 50 min · 225 flights
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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.