OnTimeStats

Airport on-time performance

Islip

Data through May 2026Source: US DOT · BTS
On-time rate73%flights departing here that arrived on time
p90 delay50 min1 in 10 departures is worse (tail risk)
Cancelled2.0%of scheduled departures
Left the gate on time75%departures that pushed back within 15 min of schedule (DepDel15)

based on 5,020 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).

As a connection hub

Arriving here (inbound performance)

These figures reflect inbound flights arriving at this airport — relevant for connections and layovers.

72%arrived on time here
(within 15 min, inbound flights)
  • On time72%
  • 15–59 min late17%
  • 1–2 hr late5%
  • 2 hr+ late3%
  • Cancelled or diverted2%

Arrival outcomes for inbound flights. Last segment = cancelled or diverted.

Bad day: 1 in 10 flights arrives more than 50 min late.

By airline

Carriers departing here (last 12 months)

Delay = arrival delay (ArrDel15-based)

  • Southwest Airlinesbest
    On-time76%
    Medianon time
    p9040 min
    Cancel1.4%
    Flights2,587
  • JetBlue Airways
    On-time69%
    Medianon time
    p9065 min
    Cancel1.9%
    Flights1,127
  • Frontier Airlines
    On-time68%
    Medianon time
    p9080 min
    Cancel2.8%
    Flights362

Over time

On-time trend

By season

On-time rate by month

When it gets busy

Busiest times at ISP

Historically, departures at ISP peak 5–10 a.m. — 30% of scheduled flights leave in that block.

  • 5–10 a.m.30%
  • 10 a.m.–2 p.m.30%
  • 2–5 p.m.20%
  • 5–8 p.m.16%
  • 8 p.m.–midnight5%

Share of 15,020 scheduled departures by planned departure time, 2023-06 .. 2026-05. Historical averages from BTS data — not live airport status.

When flights don't go

Why flights were cancelled

  • Airline21%
  • Weather64%
  • Air traffic (NAS)14%
  • Security0%

Most cancellations here are attributed to Weather. Shares are among 98 cancellations with a reported cause (BTS reports causes from June 2003).

Where flights go

Busiest routes

ISP → BWI→ISP → MCO→ISP → PBI→ISP → FLL→ISP → MDW→ISP → TPA→ISP → BOS→ISP → BNA→ISP → ATL→ISP → PVD→

Side by side

Compare this airport

Compare with Hartsfield Jackson Atlanta International Airporthead-to-head on-time→Compare with Chicago O'Hare International Airporthead-to-head on-time→Compare with Dallas Fort Worth International Airporthead-to-head on-time→Compare with Denver International Airporthead-to-head on-time→

Will you make a connection at ISP? →

Keep exploring

Related guides

When to arrive at the airportguide→Worst airports for delaysguide→

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.