Flight number record

B6 861

JetBlue Airways · Boston to San Juan

Route: BOS → SJU
Departs: 08:00
Flights: 364
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s B6 861, check with JetBlue Airways.

B6 861 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 77.3%. The late ones land about an hour behind schedule. That rests on 364 flights, with a median arrival 6 minutes early.

On time

73.4%

Arrivals under 15 minutes late, of 354 completed flights

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

2.47%

National rate is 1.89%

1 hour+ late

10.2%

National rate is 8.3%

These figures cover 364 flights between September 2025 and August 2026. Beyond the headline rate, 10.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Schedule

When B6 861 flies

B6 861 flies BOS to SJU without a single fixed slot. Its most common scheduled departure was 08:00, used on 96 of 364 flights, with 05:01 (78 flights) and 10:10 (46 flights) next.

Departs 08:0096 flights26.4%
Departs 05:0178 flights21.4%
Departs 10:1046 flights12.6%

Scale runs 0% to 100%.

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

A 08:00 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and B6 861 runs 11 points worse at 73.4%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

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Against the route

B6 861 next to BOS to SJU

Every carrier on BOS to SJU combined arrived on time 66.8% of the time across 1,717 flights, so B6 861 is 7 points ahead of it. JetBlue flew 1,142 flights on the same city pair under all its flight numbers, including this one, and those ran 66.5% on time. Across its whole network JetBlue Airways managed 71.3%, which this flight beats by 2 points.

B6 861 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
B6 861thin sample	364	73.4%	68 min	2.47%	C
All JetBlue Airways on BOS–SJU	1,142	66.5%	73 min	2.80%	C
All carriers on BOS–SJU	1,717	66.8%	76 min	2.97%	C
JetBlue Airways, whole network	240,615	71.3%	77 min	3.56%	C−

Across the year

B6 861 quarter by quarter

B6 861 did not run the same all year. Its best quarter was Oct–Dec 2025 at 82.0% on time and its weakest Jul–Sep 2026 at 54.8%, a swing of 27 points on roughly 73 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Jul–Sep 202530 flights70.0%
Oct–Dec 202591 flights82.0%
Jan–Mar 202690 flights74.4%
Apr–Jun 202691 flights78.0%
Jul–Sep 202662 flights54.8%

Scale runs 45% to 85%.

By weekday, B6 861 did best on Tuesday at 81.6% on time and worst on Thursday at 63.5%. Each day rests on about 52 flights, so a gap of 18 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late B6 861 runs when it is late

B6 861 often beats the schedule: 103 of 354 completed flights, 29%, arrived 15 minutes or more early. The 94 late arrivals split 29 under half an hour, 29 between 30 and 60 minutes, and 36 an hour or more.

15+ min early103 flights29.1%
Within 15 min157 flights44.4%
15–29 min late29 flights8.2%
30–59 min late29 flights8.2%
1–2 hours late26 flights7.3%
2+ hours late10 flights2.8%

Scale runs 0% to 100%.

Share of 354 completed flights by arrival against schedule.

13 of 74 late departures made up the time and arrived on time, 18% of them. In the other direction, 33 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SJU.

The worst days

Worst days for B6 861

The latest arrival of the period was on 19 July 2026, 6 hours 38 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in July 2026.

The latest arrivals of B6 861 in the period
Date	Arrived late by	Largest filed cause
19 July 2026	6 hours 38 minutes	Carrier
9 August 2026	5 hours 56 minutes	National Airspace System
9 July 2026	5 hours 19 minutes	Late-arriving aircraft
23 April 2026	4 hours 52 minutes	Late-arriving aircraft
23 July 2026	4 hours 12 minutes	Carrier

Delay causes

Why B6 861 runs late

National Airspace System accounts for 44% of the 6,373 delay minutes carriers reported here, and the remaining four split what is left.

National Airspace System
44%
Carrier
28%
Late-arriving aircraft
28%
Extreme weather
0%

44% 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 2,783 minutes out of 6,373, against a national NAS share of 21%. The split is drawn from 6,373 delay minutes reported on B6 861.

Cancellations sit at 2.47% against a national 1.89%, which is ordinary. Diversions add another 0.27%.

Connections and routes

What a delay on this flight costs

10.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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 364 flights under B6 861 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. 364 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 861

For a booking, read B6 861 as 73.4% on time with 2.47% cancelled over 364 flights. Those are rates from the past twelve months, not a forecast for any particular day.

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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures