OnTimeStats

Historical on-time performance

Seattle to Chicago

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

Flights on SEA–MDW arrive on time 79% of the time over the last 12 months.

On-time rate79%arrived within 15 min
p90 delay35 min1 in 10 flights is worse (tail risk)
Cancelled0.2%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-time79%
    Medianon time
    p9035 min
    Cancel0.2%
    Flights557

Why flights run late

Delay causes

  • Airline35%
  • Weather0%
  • Air traffic (NAS)13%
  • Late aircraft51%
  • 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 SEA → MDW

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

Best time of day

Mornings are the most reliable time of day to fly this route — 90% on time.

  • Mornings90% on time · p90 10 min · 820 flights
  • Overnights75% on time · p90 40 min · 119 flights · limited
  • Middays64% on time · p90 40 min · 635 flights

Best day of week

On-time rates are fairly even by day on this route — ranging from 73% to 80% on time.

  • Mondays80% on time · p90 30 min · 243 flights
  • Tuesdays80% on time · p90 25 min · 245 flights
  • Sundays79% on time · p90 35 min · 227 flights
  • Saturdays79% on time · p90 25 min · 222 flights
  • Wednesdays79% on time · p90 35 min · 245 flights
  • Thursdays73% on time · p90 30 min · 240 flights
  • Fridays73% on time · p90 30 min · 240 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.