Airport reliability
Islip (ISP) on-time performance
How reliably flights leave Islip, NY (ISP) and reach their destinations, by airline, departure hour and month, September 2025 to August 2026.
Islip, NY5,016 departures in 12 months
- Departures on time
- 73.6% U.S. average 75.6%
- Cancelled
- 2.2% U.S. average 1.9%
- 60+ minutes late
- 8.3% U.S. average 8.1%
- Scheduled departures
- 5,016 12 months
What this means
ISP departures ran below the U.S. average.
- 73.6% of the 5,016 scheduled departures from Islip (ISP) arrived at their destination on time, 2.0 points lower than the U.S. average of 75.6%.
- 2.2% of departures were cancelled (U.S. average 1.9%), and 8.3% arrived an hour or more late.
- Flights arriving at ISP were on time 73.5% of the time.
- Among airlines with at least 300 departures, Southwest Airlines was the most punctual from ISP (76.6%) and JetBlue Airways the least (69.8%).
- Over the last 3 years, October was the most reliable month for departures from ISP (86.8% on time) and August the least reliable (69.0%).
- Cancellations peaked in February, when 2.9% of flights were cancelled.
- Flights scheduled to depart before 6 am were the most punctual (89.3% on time); flights scheduled to depart 2 pm to 3 pm were the least (55.4%).
Airlines at ISP
Ranked by on-time arrival
| Airline | On time | Cancelled | 60+ min late | Avg delay when late | Departures |
|---|---|---|---|---|---|
| Southwest Airlines | 76.6% | 1.6% | 6.2% | 61 min | 2,586 |
| Frontier Airlines | 71.2% | 3.6% | 10.5% | 80 min | 830 |
| JetBlue Airways | 69.8% | 2.4% | 10.6% | 84 min | 1,600 |
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On-time rate by departure hour
Share of scheduled flights on time ISP average 73.6%
Show as table
| Period | On time | Flights |
|---|---|---|
| Departing before 6 am | 89.3% | 261 |
| Departing 6 am to 7 am | 87.9% | 670 |
| Departing 7 am to 8 am | 76.6% | 222 |
| Departing 8 am to 9 am | 78.4% | 111 |
| Departing 9 am to 10 am | 84.4% | 205 |
| Departing 10 am to 11 am | 78.8% | 326 |
| Departing 11 am to noon | 81.3% | 423 |
| Departing noon to 1 pm | 78.8% | 482 |
| Departing 1 pm to 2 pm | 65.4% | 301 |
| Departing 2 pm to 3 pm | 55.4% | 280 |
| Departing 3 pm to 4 pm | 62.7% | 501 |
| Departing 4 pm to 5 pm | 67.7% | 418 |
| Departing 5 pm to 6 pm | 60.5% | 395 |
| Departing 6 pm to 7 pm | 58.4% | 166 |
| Departing 7 pm to 8 pm | 64.6% | 113 |
| Departing 8 pm to 9 pm | 64.7% | 85 |
| Departing 9 pm to 10 pm | 77.2% | 57 |
Best and worst months at ISP
Share of scheduled flights on time 12-month average 73.6%
Show as table
| Period | On time | Flights |
|---|---|---|
| January | 72.8% | 1,325 |
| February | 76.3% | 1,323 |
| March | 72.6% | 1,363 |
| April | 79.8% | 1,431 |
| May | 77.2% | 1,346 |
| June | 76.6% | 1,261 |
| July | 70.1% | 1,313 |
| August | 69.0% | 1,234 |
| September | 81.1% | 976 |
| October | 86.8% | 1,039 |
| November | 84.2% | 1,206 |
| December | 69.6% | 1,420 |
Month by month, last 12 months
Share of scheduled flights on time U.S. average 75.6%
Show as table
| Period | On time | Flights |
|---|---|---|
| Sep 2025 | 82.6% | 351 |
| Oct 2025 | 83.8% | 365 |
| Nov 2025 | 76.5% | 395 |
| Dec 2025 | 62.9% | 458 |
| Jan 2026 | 66.9% | 435 |
| Feb 2026 | 67.7% | 433 |
| Mar 2026 | 68.0% | 413 |
| Apr 2026 | 76.8% | 462 |
| May 2026 | 82.2% | 393 |
| Jun 2026 | 79.0% | 415 |
| Jul 2026 | 70.2% | 443 |
| Aug 2026 | 71.1% | 453 |
Busiest routes from ISP
| To | On time | Cancelled | Airlines | Flights |
|---|---|---|---|---|
| Orlando (MCO) | 72.5% | 1.9% | 3 | 1,442 |
| Baltimore (BWI) | 83.6% | 1.5% | 1 | 1,259 |
| West Palm Beach/Palm Beach (DJT) | 69.5% | 2.4% | 3 | 1,230 |
| Tampa (TPA) | 68.4% | 3.9% | 3 | 433 |
| Fort Lauderdale (FLL) | 67.0% | 1.9% | 3 | 418 |
| Myrtle Beach (MYR) | 76.4% | 4.9% | 1 | 123 |
| Fort Myers (RSW) | 60.4% | 2.7% | 2 | 111 |
Sources & data dates
- Source
- U.S. DOT Bureau of Transportation Statistics, Reporting Carrier On-Time Performance (1987-present)
- Period
- September 2025 to August 2026 (12 months); month-of-year patterns September 2023 to August 2026
- Data through
- August 2026
- Processed
- 2026-11-03
- Scope
- Scheduled nonstop domestic departures from Islip, NY (ISP) by airlines that report to the DOT.
- Method
- Rates use all scheduled flights as the denominator; cancelled and diverted flights count as not on time. Figures based on fewer than 50 scheduled flights are suppressed. Full methodology.