Route reliability record
BOS→FLL
Boston to Fort Lauderdale
- Flights
- 3,417
- Period
- July 2025 to June 2026
- Distance
- 1,237 mi
- Carriers
- 3
This route carries a cancellation problem, not just a delay problem: 3.5% of scheduled flights never operate, against 1.8% nationally. Of the ones that do fly, about two flights in three arrive on time, worth a C− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 3,417 flights, of which Delta Air Lines flew 885 at 69.5% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 69.5% on time across 885 flights.
Key figures
On time
66.7%
Arrivals under 15 minutes late, of 3,285 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
3.45%
National rate is 1.81%
Best carrier
Delta
69.5% on time across 885 flights
These figures cover 3,417 flights between July 2025 and June 2026. Beyond the headline rate, 13.7% 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 BOS to FLL
The three 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 |
|---|---|---|---|---|---|
| Delta Air Lines | 885 | 69.5% | 78 min | 3.05% | C− |
| JetBlue Airways | 1,961 | 66.1% | 69 min | 3.16% | C− |
| Spirit Airlines | 571 | 64.6% | 82 min | 5.08% | D− |
Spirit Airlines cancels 5.1% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
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 27 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,017 flights80.0%
- 8am–11am468 flights76.3%
- 11am–2pm309 flights63.7%
- 2pm–5pm636 flights59.4%
- 5pm–8pm609 flights53.3%
- 8pm–5am378 flights55.6%
Scale runs 45% to 85%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 53.3% on time, against 80.0% 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 5am–8am window is the busiest, with 1,017 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 24 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.
December is the weak month at 53.1% on time, against 77.6% in June. 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. March was the busiest month here, with 390 flights.
Across the week, Wednesday is the strongest day at 76.7% on time and Sunday the weakest at 57.7%. 19 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 80,000 reported delay minutes.
- 36%Late-arriving aircraft
- 33%National Airspace System
- 28%Carrier
- 2%Extreme weather
- 0%Security
36% 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 80,000 reported delay minutes here, that single category outweighs weather by 15 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 79,945 reported delay minutes.
33% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 26,000 minutes out of 80,000, against a national NAS share of 21%.
Cancellations run at 3.45%, against 1.81% nationally. That is about one flight in 30 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
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. 13.7% 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 1,237 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 66.5% on time across 3,406 flights, within half a point 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 3,417 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.
What to do with this
Booking this route
Put together: the delay figures matter less here than the 3.45% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 3,285 completed flights over 12 months sit behind that.
Common questions
BOS to FLL questions
How often is BOS to FLL delayed?
About one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 33.3% of the 3,417 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on BOS to FLL?
Delta Air Lines leads at 69.5% on time across 885 flights. Spirit Airlines is at the other end on 64.6%, 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 BOS to FLL?
The 5am–8am departure window is the strongest at 80.0% on time. The 5pm–8pm window is the weakest at 53.3%, 27 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 December delays on BOS to FLL?
December is the weakest month at 53.1% on time, compared with 77.6% in June. Across the year that is 24 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
- FLL to BOS — the return legseparate record
- Boston Logan International (BOS) delay statistics
- Fort Lauderdale-Hollywood International (FLL) delay statistics
- Delta Air Lines on-time record69.5%
- JetBlue Airways on-time record66.1%
- Spirit Airlines on-time record64.6%
- Why the first flight of the morning is statistically safest
- What a cancellation rate actually tells you (and what it hides)
Direction matters. BOS to FLL and FLL to BOS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.