According to PlainFlights' airport traffic ranking (BTS On-Time Performance total flights), Islip, NY (ISP) ranks #142 of 382 tracked US airports by total flights (most flights = #1). Islip, NY posts bottom-quartile on-time performance among the 382 tracked U.S. airports, as a mid-size U.S. airport.
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ISP on-time rate vs. the national average
Behind the U.S. average across all 382 tracked airports.
Volume vs. on-time rate
Where Islip, NY sits on volume vs. on-time rate
Among the 382 U.S. airports in the BTS corpus, Islip, NY handles more flight
volume than 63% of them, and has a higher on-time rate than
8% of them, placing it in the quadrant for busy and delay-prone.
Flight volume and on-time rate are independent figures: a busy airport can still run
reliably, and a quiet one can still run late.
Islip, NY vs. a 29-airport national peer sample, volume percentile vs. on-time-rate percentile.
Total flights (2020-2025): 54,300 ·
On-time rate: 77.9%
Delay Cause Breakdown
Top delay cause: Late Aircraft.
Total delay minutes400,850 min
Late Aircraft180,201 min · 45%
Carrier105,784 min · 26%
NAS (National Aviation System)102,342 min · 26%
Weather12,197 min · 3%
Security326 min · 0%
Source: U.S. DOT Bureau of Transportation Statistics, On-Time Performance
ISP - seasonal on-time pattern
Best: November (92%) · worst: July (85.3%)
ISP - on-time rate by year
2020–2025, year-over-year trend.
ISP - taxi-out and taxi-in (monthly)
Average taxi-out 12.4 min · taxi-in 4.9 min over the last 24 reported months (U.S. airport mean taxi-out ≈ 16.4 min).
ISP's average taxi-out (12.4 min) stays shorter than the recent U.S. airport mean (~16.4 min). Even the heaviest month (December 2025, 15.4 min) is milder than many hubs' typical book.
Two PlainFlights-derived comparison paths for Islip, NY, both outside New York so the neighborhoods are not same-state geography. Axes stay disjoint: volume peers exclude the on-time peer set. Same-state compare stays below.
The standout signal at Islip, NY is the delay mix: Late Aircraft owns 45.0% of 400,850 delay minutes across 54,300 BTS flights. The on-time headline is 77.9% (1.1 pts below the 79% national average), with 11,984 delayed and 881 cancelled (1.62%).
Delay minutes concentrate in Late Aircraft (45.0% late-aircraft, 26.4% carrier, 25.5% NAS, 3.0% weather, 0.1% security). Mid-volume books still show a clear delay fingerprint rather than a weather-only story.
On the multi-year calendar, ISP is strongest in November (92% on-time) and weakest in July (85.3%), a 6.7-point swing. Volume peaks in March (~891 flights/month). The busiest connecting route is to MCO (Orlando) at 77.6% on-time. Field definitions: on-time performance explained.
Islip, NY vs. the national on-time distribution
On-time rate among all 382 tracked U.S. airports
77.9%Top 92%higher than 8% of 382 airports
Islip, NY
60%95%
U.S. airports by on-time rate, bucketed by value
Each bar is a band; taller bars hold more airports. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data (2020–2025).
Statistics reflect cumulative performance across all available reporting periods. On-time rates exclude cancelled and diverted flights.
ISP's on-time book sits in the slower half of the BTS set; check the delay mix and the worst month before treating the headline as typical.
Check the busiest route from ISP before you book a connection. See top routes →
Travel in November rather than July if your dates are flexible. Seasonal patterns →
Gate-to-wheels taxi-out averages 12.4 min here; check the monthly series before a tight connection. Taxi times →
On-time rate reflects the BTS historical average across all reporting carriers at this airport, not any single flight or airline.
Frequently Asked Questions
What is Islip, NY's on-time rate?
Islip, NY (ISP) has a 77.9% on-time rate across 54,300 BTS-tracked flights (2020-2025), 1.1 pts below the 79% national flight-weighted average; that places it in roughly the bottom-quartile on-time performance.
How does ISP rank among U.S. airports by traffic volume?
Islip, NY ranks #142 of 382 tracked US airports by total BTS flights (most flights = #1), making it a mid-size U.S. airport.
What's the most common cause of delays at Islip, NY?
Late Aircraft is the leading delay cause at ISP, accounting for 45.0% of delay minutes. The full breakdown: 45.0% late-aircraft, 26.4% carrier, 25.5% NAS/air-traffic-control, 3.0% weather, and 0.1% security.
When is the best time to fly through Islip, NY?
November is historically ISP's strongest month at 92% on-time, while July is the weakest at 85.3%, a 6.7-point swing across the BTS historical record.