OnTimeStats

Historical on-time performance

Washington to San Diego

2,253 miData through Dec 2025Source: US DOT · BTS

Flights on IAD–SAN arrive on time 80% of the time over the last 12 months.

On-time rate80%arrived within 15 min
p90 delay35 min1 in 10 flights is worse (tail risk)
Cancelled0.2%of scheduled flights

based on 1,390 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

By airline

How each carrier compares

  • United Airlinesbest
    On-time82%
    Medianon time
    p9030 min
    Cancel0.2%
    Flights1,085
  • Alaska Airlines
    On-time71%
    Medianon time
    p9055 min
    Cancel0.3%
    Flights305

Why flights run late

Delay causes

  • Airline21%
  • Weather13%
  • Air traffic (NAS)36%
  • Late aircraft29%
  • Security0%

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

Over time

On-time trend

By season

On-time rate by month

When to fly

Best time to fly IAD → SAN

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 · 1,413 flights
  • Middays86% on time · p90 25 min · 1,158 flights
  • Afternoons78% on time · p90 30 min · 210 flights
  • Evenings73% on time · p90 45 min · 1,641 flights

Best day of week

On-time rates are fairly even by day on this route — ranging from 79% to 86% on time.

  • Tuesdays86% on time · p90 20 min · 640 flights
  • Mondays85% on time · p90 25 min · 637 flights
  • Saturdays82% on time · p90 35 min · 612 flights
  • Fridays81% on time · p90 30 min · 635 flights
  • Wednesdays81% on time · p90 30 min · 640 flights
  • Sundays80% on time · p90 35 min · 629 flights
  • Thursdays79% on time · p90 25 min · 629 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.