OnTimeStats

Historical on-time performance

Portland to Chicago

1,751 miData through Dec 2025Source: US DOT · BTS

Flights on PDX–MDW arrive on time 87% of the time over the last 12 months.

On-time rate87%arrived within 15 min
p90 delay20 min1 in 10 flights is worse (tail risk)
Cancelled0.2%of scheduled flights

based on 571 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

By airline

How each carrier compares

  • Southwest Airlines
    On-time87%
    Medianon time
    p9020 min
    Cancel0.2%
    Flights571

Why flights run late

Delay causes

  • Airline44%
  • Weather0%
  • Air traffic (NAS)13%
  • Late aircraft42%
  • Security1%

Most delay minutes here are attributed to Airline.

Over time

On-time trend

By season

On-time rate by month

When to fly

Best time to fly PDX → 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 — 93% on time.

  • Mornings93% on time · p90 5 min · 1,057 flights
  • Middays81% on time · p90 20 min · 494 flights
  • Afternoons62% on time · p90 35 min · 119 flights · limited

Best day of week

On-time rates are fairly even by day on this route — ranging from 81% to 91% on time.

  • Saturdays91% on time · p90 10 min · 225 flights
  • Tuesdays90% on time · p90 10 min · 252 flights
  • Mondays87% on time · p90 15 min · 255 flights
  • Fridays87% on time · p90 15 min · 254 flights
  • Wednesdays87% on time · p90 15 min · 252 flights
  • Thursdays85% on time · p90 20 min · 254 flights
  • Sundays81% on time · p90 20 min · 203 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.