OnTimeStats

Historical on-time performance

Chicago to Seattle

1,733 miData through May 2026Source: US DOT · BTS

Flights on MDW–SEA arrive on time 64% of the time over the last 12 months.

On-time rate64%arrived within 15 min
p90 delay50 min1 in 10 flights is worse (tail risk)
Cancelled0.5%of scheduled flights

based on 645 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

By airline

How each carrier compares

  • Southwest Airlines
    On-time64%
    Medianon time
    p9050 min
    Cancel0.5%
    Flights645

Why flights run late

Delay causes

  • Airline27%
  • Weather3%
  • Air traffic (NAS)23%
  • Late aircraft46%
  • Security1%

Most delay minutes here are attributed to Late aircraft.

When flights don't go

Why flights were cancelled

  • Airline33%
  • Weather67%
  • Air traffic (NAS)0%
  • Security0%

Most cancellations here are attributed to Weather. Shares are among 3 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 MDW → SEA

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 56% to 74% on time.

  • Middays74% on time · p90 30 min · 469 flights
  • Mornings73% on time · p90 35 min · 382 flights
  • Evenings67% on time · p90 55 min · 172 flights · limited
  • Afternoons58% on time · p90 60 min · 401 flights
  • Overnights56% on time · p90 55 min · 333 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 35 min · 256 flights
  • Tuesdays69% on time · p90 45 min · 256 flights
  • Mondays67% on time · p90 45 min · 258 flights
  • Sundays66% on time · p90 50 min · 233 flights
  • Thursdays63% on time · p90 45 min · 259 flights
  • Fridays63% on time · p90 55 min · 259 flights
  • Saturdays63% on time · p90 50 min · 236 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.