Carrier route record

DLFLL→BOS

Delta Air Lines · Fort Lauderdale to Boston

Flights: 884
Period: July 2025 to June 2026
Share of route: 26%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on FLL to BOS sits in the middle of the pack with a C−. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 884 flights. The strongest carrier on the route with a full sample, JetBlue Airways, flew 1,952 at 65.6% on time.

The national on-time rate over the same period is 77.6%, so Delta on FLL to BOS runs 6 points behind the country as a whole. Across a thousand flights that is about 58 extra late arrivals.

On time

71.8%

Arrivals under 15 minutes late, of 857 completed flights

Avg delay

79 min

Across delayed arrivals only, not all flights

Cancelled

3.05%

National rate is 1.81%

Whole route

66.5%

Every carrier on FLL to BOS, 3,406 flights

These figures cover 884 flights between July 2025 and June 2026. Beyond the headline rate, 12.8% 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

Delta against every carrier on FLL to BOS

Delta flew 884 of the 3,406 flights on FLL to BOS, about 26% of it. Its 71.8% on time is 5 points better than the route as a whole, which runs 66.5%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 71.8% to Spirit at 61.7%.

The two carriers here are closely matched: 4 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.

On-time performance by carrier on FLL to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	884	71.8%	79 min	3.05%	C−
JetBlue Airways	1,952	65.6%	78 min	2.92%	C
Spirit Airlines	570	61.7%	77 min	4.74%	D−

Spirit Airlines cancels 4.7% 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.

Flight by flight

Delta flight numbers on FLL to BOS

DL 140111:5968.1% · 309 flights

Departure window

When Delta runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am179 flights86.6%
8am–11am—
11am–2pm365 flights70.9%
2pm–5pm13 flights—
5pm–8pm32 flights64.5%
8pm–5am295 flights66.5%

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 64.5% on time, against 86.6% 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 365 flights scheduled in it.

Across the year

Delta on FLL to BOS through the year

Darker means more delays. Figures are on-time percentages.May best, July worst

July is the worst month at 51.7% on time, 35 points below May, the best at 86.8%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. December was the busiest month here, with 90 flights.

Across the week, Wednesday is the strongest day at 75.8% on time and Sunday the weakest at 67.8%. 8 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 43% of the 19,000 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.

Late-arriving aircraft
43%
Carrier
33%
National Airspace System
22%
Extreme weather
2%

43% 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 19,000 reported delay minutes here, that single category outweighs weather by 28 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 19,207 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 86.6% on time here.

Cancellations run at 3.05%, against 1.81% nationally. That is roughly 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 costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 12.8% 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 69.5% on time across 885 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.

One caution: this is a thin sample. 884 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 Delta on FLL to BOS

Put together: the delay figures matter less here than the 3.05% 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. 857 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures