OnTimeStats

Historical on-time performance

Seattle to Denver

1,024 miData through May 2026Source: US DOT · BTS

Flights on SEA–DEN arrive on time 76% of the time over the last 12 months.

On-time rate76%arrived within 15 min
p90 delay40 min1 in 10 flights is worse (tail risk)
Cancelled0.8%of scheduled flights

based on 6,208 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.

  • United Airlines
    On-time85%
    Medianon time
    p9020 min
    Cancel0.8%
    Flights1,906
  • SkyWest Airlines
    On-time85%
    Medianon time
    p9030 min
    Cancel0.5%
    Flights215
  • Alaska Airlines
    On-time73%
    Medianon time
    p9045 min
    Cancel0.8%
    Flights1,571
  • Frontier Airlines
    On-time72%
    Medianon time
    p9045 min
    Cancel2.1%
    Flights329
  • Delta Air Lines
    On-time71%
    Medianon time
    p9055 min
    Cancel1.0%
    Flights841
  • Southwest Airlines
    On-time69%
    Medianon time
    p9050 min
    Cancel0.6%
    Flights1,346

Why flights run late

Delay causes

  • Airline29%
  • Weather5%
  • Air traffic (NAS)34%
  • Late aircraft32%
  • Security0%

Most delay minutes here are attributed to Air traffic (NAS).

When flights don't go

Why flights were cancelled

  • Airline48%
  • Weather27%
  • Air traffic (NAS)25%
  • Security0%

Most cancellations here are attributed to Airline. Shares are among 52 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 SEA → DEN

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 · 6,769 flights
  • Middays74% on time · p90 35 min · 4,642 flights
  • Evenings73% on time · p90 50 min · 2,994 flights
  • Overnights69% on time · p90 50 min · 1,571 flights
  • Afternoons68% on time · p90 60 min · 3,634 flights

Best day of week

On-time rates are fairly even by day on this route — ranging from 75% to 80% on time.

  • Wednesdays80% on time · p90 30 min · 2,719 flights
  • Saturdays79% on time · p90 35 min · 2,591 flights
  • Tuesdays78% on time · p90 35 min · 2,637 flights
  • Mondays77% on time · p90 40 min · 2,909 flights
  • Thursdays76% on time · p90 40 min · 2,924 flights
  • Fridays75% on time · p90 45 min · 2,936 flights
  • Sundays75% on time · p90 45 min · 2,894 flights

Keep exploring

Related pages

Delay predictorfor this route→SEA airportSeattle→DEN airportDenver→United Airlinesairline profile→Alaska Airlinesairline profile→Southwest Airlinesairline 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.