Route reliability record
PBI→ISP
West Palm Beach to Islip
- Flights
- 1,223
- Period
- July 2025 to June 2026
- Distance
- 1,052 mi
- Carriers
- 3
This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,223 PBI to ISP flights, of which JetBlue Airways flew 542 at 77.5% on time.
Best time to fly PBI to ISP: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 91.8% of the time and Wednesday flights 82.4%, against 73.6% for the route overall.
The national on-time rate over the same period is 77.6%, so this route runs 4 points behind the country as a whole. Across a thousand flights that is about 40 extra late arrivals.
Key figures
On time
73.6%
Arrivals under 15 minutes late, of 1,200 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
1.64%
National rate is 1.81%
Best carrier
JetBlue
77.5% on time across 542 flights
These figures cover 1,223 flights between July 2025 and June 2026. Beyond the headline rate, 9.0% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on PBI to ISP
The two carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| JetBlue Airways | 542 | 77.5% | 65 min | 1.85% | B |
| Southwest Airlines | 610 | 72.8% | 59 min | 0.98% | C+ |
| Frontier Airlinesthin sample | 71 | 48.5% | 70 min | 5.63% | F− |
No carrier stands out. JetBlue tops the table at 77.5%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on PBI to ISP
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Best ways to make this trip
The most reliable ways to fly West Palm Beach to Islip
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 4 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. PBI → ISPWest Palm Beach to Islip | JetBlue Airways | 76.1% | 77.5% | 1.85% | 5am–8am, Tue | B6 544 10:09 |
| 2. FLL → EWRFort Lauderdale to Newark | United Airlines | 75.6% | 77.3% | 2.20% | 5am–8am, Tue | — |
| 3. PBI → EWRWest Palm Beach to Newark | United Airlines | 74.6% | 76.3% | 2.24% | 5am–8am, Tue | UA 1391 10:00 |
| 4. PBI → JFKWest Palm Beach to New York | JetBlue Airways | 73.6% | 76.3% | 3.52% | 5am–8am, Tue | B6 854 08:15 |
| 5. FLL → JFKFort Lauderdale to New York | Delta Air Lines | 73.6% | 76.4% | 3.65% | 5am–8am, Sat | DL 2165 07:00 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 44 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am87 flights91.8%
- 8am–11am238 flights84.3%
- 11am–2pm497 flights76.7%
- 2pm–5pm122 flights65.3%
- 5pm–8pm119 flights47.9%
- 8pm–5am160 flights63.2%
Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 47.9% on time, against 91.8% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 11am–2pm window is the busiest, with 497 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 29 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
February is the weak month at 62.4% on time, against 91.2% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. February was the busiest month here, with 134 flights.
Across the week, Wednesday is the strongest day at 82.4% on time and Sunday the weakest at 67.6%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 64% of the 20,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 64%Late-arriving aircraft
- 21%Carrier
- 13%National Airspace System
- 1%Extreme weather
- 0%Security
64% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 20,000 reported delay minutes here, that single category outweighs weather by 46 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 19,710 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 91.8% on time here.
Cancellations sit at 1.64% against a national 1.81%, which is ordinary. Diversions add another 0.25%.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.0% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 1,052 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 71.9% on time across 1,223 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 1,223 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in ISP after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 91.2% on time and February 62.4%, a swing of 29 points. If the dates move at all, move them out of February before you think about anything else. 1,200 completed flights over 12 months sit behind that.
Common questions
PBI to ISP questions
How often is PBI to ISP delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 26.4% of the 1,223 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on PBI to ISP?
JetBlue Airways leads at 77.5% on time across 542 flights. Southwest Airlines is at the other end on 72.8%, a gap of 5 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on PBI to ISP?
The 5am–8am departure window is the strongest at 91.8% on time. The 5pm–8pm window is the weakest at 47.9%, 44 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are February delays on PBI to ISP?
February is the weakest month at 62.4% on time, compared with 91.2% in October. Across the year that is 29 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- ISP to PBI — the return legseparate record
- JetBlue Airways on PBI to ISP77.5%
- Southwest Airlines on PBI to ISP72.8%
- PBI to ATL, a related route82.9%
- MCO to ISP, a related route74.8%
- PBI to EWR, a related route74.5%
- JetBlue Airways on-time record77.5%
- Southwest Airlines on-time record72.8%
- Frontier Airlines on-time record48.5%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. PBI to ISP and ISP to PBI are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.