OnTimeStats

Historical on-time performance

Portland to Chicago

895 miData through Dec 2025Source: US DOT · BTS

Flights on PWM–MDW arrive on time 76% of the time over the last 12 months.

On-time rate76%arrived within 15 min
p90 delay65 min1 in 10 flights is worse (tail risk)
Cancelled2.4%of scheduled flights

based on 123 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

By airline

How each carrier compares

  • Southwest Airlines
    On-time76%
    Medianon time
    p9065 min
    Cancel2.4%
    Flights123

Why flights run late

Delay causes

  • Airline25%
  • Weather1%
  • Air traffic (NAS)17%
  • Late aircraft57%
  • Security0%

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 PWM → MDW

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 57% to 96% on time.

  • Middays96% on time · p90 5 min · 56 flights · limited
  • Mornings88% on time · p90 25 min · 51 flights · limited
  • Afternoons78% on time · p90 35 min · 126 flights · limited
  • Evenings57% on time · p90 90 min · 223 flights

Best day of week

On-time rates are fairly even by day on this route — ranging from 56% to 82% on time.

  • Wednesdays82% on time · p90 70 min · 65 flights · limited
  • Tuesdays78% on time · p90 30 min · 65 flights · limited
  • Mondays77% on time · p90 125 min · 64 flights · limited
  • Thursdays73% on time · p90 55 min · 66 flights · limited
  • Sundays67% on time · p90 90 min · 64 flights · limited
  • Fridays67% on time · p90 75 min · 66 flights · limited
  • Saturdays56% on time · p90 60 min · 66 flights · limited
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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.