Flight number record

B6 561

JetBlue Airways · Boston to San Juan

Route: BOS → SJU
Departs: 20:45
Flights: 274
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s B6 561, check with JetBlue Airways.

B6 561 earns an F, which is as low as this site's scale goes for a reason. Only 54.7% of flights arrive inside the 15-minute window, 23 points worse than the national rate of 77.6%. Late arrivals average a little over an hour. Treat any tight connection here as a coin flip. That rests on 274 flights, with a median arrival 11 minutes late.

The national on-time rate over the same period is 77.6%, so B6 561 runs 23 points behind the country as a whole. Across a thousand flights that is about 229 extra late arrivals.

On time

54.7%

Arrivals under 15 minutes late, of 267 completed flights

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

2.55%

National rate is 1.81%

1 hour+ late

18.7%

National rate is 8.1%

These figures cover 274 flights between July 2025 and June 2026. Beyond the headline rate, 18.7% 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.

Schedule

When B6 561 flies

B6 561 flies BOS to SJU without a single fixed slot. Its most common scheduled departure was 20:45, used on 63 of 274 flights, with 18:45 (30 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 20:4563 flights23.0%
Departs 18:4530 flights10.9%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 20:45 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and B6 561 runs 16 points worse at 54.7%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

B6 561 next to BOS to SJU

Every carrier on BOS to SJU combined arrived on time 69.0% of the time across 1,819 flights, so B6 561 is 14 points behind it. JetBlue flew 1,232 flights on the same city pair under all its flight numbers, including this one, and those ran 69.2% on time. Across its whole network JetBlue Airways managed 72.7%, which this flight trails by 18 points.

B6 561 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
B6 561thin sample	274	54.7%	71 min	2.55%	F
All JetBlue Airways on BOS–SJU	1,232	69.2%	71 min	2.44%	C
All carriers on BOS–SJU	1,819	69.0%	74 min	2.69%	C
JetBlue Airways, whole network	234,468	72.7%	76 min	2.56%	C

Across the year

B6 561 quarter by quarter

Quarter by quarter B6 561 held fairly steady: 59.7% in Jul–Sep 2025, 50.9% in Oct–Dec 2025, 52.5% in Jan–Mar 2026 and 55.7% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202564 flights59.7%
Oct–Dec 202555 flights50.9%
Jan–Mar 202685 flights52.5%
Apr–Jun 202670 flights55.7%

Scale runs 40% to 65%. Rows with fewer than 30 flights show a dash.

By weekday, B6 561 did best on Wednesday at 61.1% on time and worst on Sunday at 40.0%. Each day rests on about 39 flights, so a gap of 21 points is worth noticing but could still narrow in another year.

Delay causes

Why B6 561 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 45% of the 8,582 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
45%
Carrier
32%
National Airspace System
19%
Extreme weather
4%

45% 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 8,582 reported delay minutes here, that single category outweighs weather by 11 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 8,582 delay minutes reported on B6 561.

Cancellations run at 2.55%, against 1.81% nationally. That is about one flight in 40 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 routes

What a delay on this flight costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 18.7% 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.

At 1,674 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.

Every one of the 274 flights under B6 561 in the data flew BOS to SJU. The number was not reused on any other city pair, which makes this a clean record of one route.

One caution: this is a thin sample. 274 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 B6 561

For a booking, the cancellation rate is the figure to plan around on B6 561: 2.55% of its 274 scheduled flights did not operate. A late arrival costs a little over an hour, but a cancellation costs the day, so leave a later option open.

Where to go next

A flight number here means JetBlue Airways’s own number as it reports to the DOT. How the figures are computed is on the methodology page.

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