OnTimeStats

Historical on-time performance

SFOBOS

San Francisco to Boston

2,704 miData through Dec 2025Source: US DOT · BTS

Flights on SFO–BOS arrive on time 79% of the time over the last 12 months.

On-time rate79%arrived within 15 min
Median delayon timetypical arrival
p90 delay45 min1 in 10 flights is worsetail risk
Cancelled0.5%of scheduled flights

based on 4,529 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-time78%
    Medianon time
    p9040 min
    Cancel0.6%
    Flights863
  • JetBlue Airways
    On-time78%
    Medianon time
    p9055 min
    Cancel0.8%
    Flights1,553
  • United Airlinesbest
    On-time81%
    Medianon time
    p9045 min
    Cancel0.2%
    Flights1,772
  • Alaska Airlines
    On-time78%
    Medianon time
    p9025 min
    Cancel0.3%
    Flights341

Why flights run late

Delay causes

  • Airline21%
  • Weather1%
  • Air traffic (NAS)44%
  • Late aircraft34%
  • Security0%

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

Over time

On-time trend

By season

On-time rate by month

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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.