OnTimeStats

Historical on-time performance

San Antonio to Boston

1,764 miData through May 2026Source: US DOT · BTS

Flights on SAT–BOS arrive on time 55% of the time over the last 12 months.

On-time rate55%arrived within 15 min
p90 delay110 min1 in 10 flights is worse (tail risk)
Cancelled1.2%of scheduled flights

based on 242 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

By airline

How each carrier compares

  • Delta Air Lines
    On-time55%
    Median10 min
    p90110 min
    Cancel1.2%
    Flights242

Why flights run late

Delay causes

  • Airline9%
  • Weather4%
  • Air traffic (NAS)60%
  • Late aircraft27%
  • Security0%

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

When flights don't go

Why flights were cancelled

  • Airline100%
  • Weather0%
  • Air traffic (NAS)0%
  • Security0%

Most cancellations here are attributed to Airline. Shares are among 3 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 SAT → BOS

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

Best time of day

On-time rates are fairly even by time of day on this route — ranging from 63% to 63% on time.

  • Afternoons63% on time · p90 90 min · 407 flights
  • Middays63% on time · p90 85 min · 549 flights

Best day of week

On-time rates are fairly even by day on this route — ranging from 56% to 67% on time.

  • Saturdays67% on time · p90 75 min · 132 flights · limited
  • Sundays66% on time · p90 75 min · 150 flights · limited
  • Tuesdays66% on time · p90 70 min · 149 flights · limited
  • Wednesdays66% on time · p90 115 min · 148 flights · limited
  • Mondays62% on time · p90 80 min · 154 flights · limited
  • Thursdays62% on time · p90 90 min · 151 flights · limited
  • Fridays56% on time · p90 100 min · 151 flights · limited

Keep exploring

Related pages

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.