OnTimeStats

Historical on-time performance

Boston to Chicago

867 miData through May 2026Source: US DOT · BTS

Flights on BOS–ORD arrive on time 70% of the time over the last 12 months.

On-time rate70%arrived within 15 min
p90 delay70 min1 in 10 flights is worse (tail risk)
Cancelled2.7%of scheduled flights

based on 7,456 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

By airline

How each carrier compares

Too close to call — no single carrier is clearly more on-time here.

  • Envoy Air
    On-time73%
    Medianon time
    p9070 min
    Cancel3.2%
    Flights431
  • JetBlue Airways
    On-time73%
    Medianon time
    p9060 min
    Cancel1.8%
    Flights508
  • United Airlines
    On-time73%
    Medianon time
    p9055 min
    Cancel1.8%
    Flights2,631
  • American Airlines
    On-time71%
    Medianon time
    p9080 min
    Cancel2.6%
    Flights2,098
  • Republic Airways
    On-time66%
    Medianon time
    p9070 min
    Cancel6.2%
    Flights827
  • Delta Air Lines
    On-time63%
    Medianon time
    p9080 min
    Cancel2.5%
    Flights961

Why flights run late

Delay causes

  • Airline21%
  • Weather2%
  • Air traffic (NAS)35%
  • Late aircraft41%
  • Security0%

Most delay minutes here are attributed to Late aircraft.

When flights don't go

Why flights were cancelled

  • Airline13%
  • Weather64%
  • Air traffic (NAS)24%
  • Security0%

Most cancellations here are attributed to Weather. Shares are among 200 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 BOS → ORD

All airlines · rolling 36 months (2023-06 .. 2026-05).

Best time of day

Mornings are the most reliable time of day to fly this route — 87% on time.

  • Mornings87% on time · p90 15 min · 7,317 flights
  • Middays82% on time · p90 35 min · 4,569 flights
  • Afternoons68% on time · p90 75 min · 4,464 flights
  • Overnights59% on time · p90 110 min · 842 flights
  • Evenings57% on time · p90 100 min · 3,683 flights

Best day of week

On-time rates are fairly even by day on this route — ranging from 72% to 79% on time.

  • Tuesdays79% on time · p90 45 min · 2,868 flights
  • Wednesdays78% on time · p90 45 min · 2,901 flights
  • Saturdays78% on time · p90 45 min · 2,541 flights
  • Mondays75% on time · p90 60 min · 3,160 flights
  • Thursdays74% on time · p90 60 min · 3,147 flights
  • Fridays73% on time · p90 60 min · 3,165 flights
  • Sundays72% on time · p90 65 min · 3,093 flights

Keep exploring

Related pages

Delay predictorfor this route→BOS airportBoston→ORD airportChicago→United Airlinesairline profile→American Airlinesairline profile→Delta Air Linesairline profile→Seasonal delay patternsguide→

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.