Carrier route record
WNMCO→ISP
Southwest Airlines · Orlando to Islip
- Flights
- 677
- Period
- July 2025 to June 2026
- Share of route
- 47%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on MCO to ISP draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is roughly 50 minutes behind schedule. Build slack into anything you connect to. That rests on 677 flights. The strongest carrier on the route with a full sample, JetBlue Airways, flew 374 at 88.3% on time.
The national on-time rate over the same period is 77.6%, so Southwest on MCO to ISP runs 11 points behind the country as a whole. Across a thousand flights that is about 105 extra late arrivals.
Key figures
On time
67.1%
Arrivals under 15 minutes late, of 666 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
1.62%
National rate is 1.81%
Whole route
74.8%
Every carrier on MCO to ISP, 1,427 flights
These figures cover 677 flights between July 2025 and June 2026. Beyond the headline rate, 8.4% 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
Southwest against every carrier on MCO to ISP
Southwest flew 677 of the 1,427 flights on MCO to ISP, about 47% of it. Its 67.1% on time is 8 points worse than the route as a whole, which runs 74.8%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from JetBlue at 88.3% to Southwest at 67.1%.
The choice of carrier is not cosmetic here. JetBlue Airways arrives on time 88.3% of the time; Frontier Airlines manages 75.1%. Sample sizes sit next to every figure, because a two-point gap across 376 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| JetBlue Airways | 374 | 88.3% | 55 min | 1.34% | A |
| Frontier Airlines | 376 | 75.1% | 81 min | 2.39% | B |
| Southwest Airlines (this page) | 677 | 67.1% | 51 min | 1.62% | C |
The spread between JetBlue and Frontier is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 more arrivals inside the on-time window.
Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 44 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am40 flights97.5%
- 8am–11am196 flights81.4%
- 11am–2pm92 flights64.1%
- 2pm–5pm47 flights65.2%
- 5pm–8pm137 flights56.7%
- 8pm–5am165 flights53.1%
Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 53.1% on time, against 97.5% 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 8am–11am window is the busiest, with 196 flights scheduled in it.
Across the year
Southwest on MCO to ISP through the year
December is the weak month at 47.6% on time, against 87.2% in September. 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. May was the busiest month here, with 66 flights.
Across the week, Tuesday is the strongest day at 77.5% on time and Monday the weakest at 59.8%. 18 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 51% of the 11,000 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.
- 51%Late-arriving aircraft
- 33%Carrier
- 14%National Airspace System
- 2%Extreme weather
- 1%Security
51% 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 11,000 reported delay minutes here, that single category outweighs weather by 23 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 11,250 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 97.5% on time here.
Cancellations sit at 1.62% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
8.4% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 50 minutes, which a normal layover absorbs.
The 971 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 is a different operation and performs like one: it runs 73.4% on time across 678 flights, 6 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 6 points of difference.
One caution: this is a thin sample. 677 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking Southwest on MCO to ISP
Put together: treat all of this as provisional. 677 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 67.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 666 completed flights over 12 months sit behind that.
Related
Where to go next
- MCO to ISP, every carrier
- Southwest on ISP to MCO, the return leg
- JetBlue Airways on MCO to ISP88.3%
- Frontier Airlines on MCO to ISP75.1%
- Southwest Airlines network-wide record
- Orlando International (MCO) delay statistics
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
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.