Flight number record

B6 2120

JetBlue Airways · San Diego to Boston

Route: SAN → BOS
Departs: 21:00
Flights: 364
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s B6 2120, check with JetBlue Airways.

B6 2120 earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.6%. When something does go wrong the average delay runs close to two hours. That rests on 364 flights, with a median arrival 19 minutes early.

Set against the rest of the country, B6 2120's record is 7 points better than the US average of 77.6%. That gap is worth roughly 72 fewer late arrivals for every thousand flights.

On time

84.8%

Arrivals under 15 minutes late, of 361 completed flights

Avg delay

112 min

Across delayed arrivals only, not all flights

Cancelled

0.82%

National rate is 1.81%

1 hour+ late

7.5%

National rate is 8.1%

These figures cover 364 flights between July 2025 and June 2026. The median arrival is 19 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Schedule

When B6 2120 flies

B6 2120 flies SAN to BOS without a single fixed slot. Its most common scheduled departure was 21:00, used on 51 of 364 flights, with 20:44 (48 flights) and 20:55 (46 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 21:0051 flights14.0%
Departs 20:4448 flights13.2%
Departs 20:5546 flights12.6%

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 21:00 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and B6 2120 runs 14 points better at 84.8%. 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 2120 next to SAN to BOS

Every carrier on SAN to BOS combined arrived on time 77.9% of the time across 1,818 flights, so B6 2120 is 7 points ahead of it. JetBlue flew 919 flights on the same city pair under all its flight numbers, including this one, and those ran 79.3% on time. Across its whole network JetBlue Airways managed 72.7%, which this flight beats by 12 points.

B6 2120 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
B6 2120thin sample	364	84.8%	112 min	0.82%	B+
All JetBlue Airways on SAN–BOS	919	79.3%	99 min	1.41%	B
All carriers on SAN–BOS	1,818	77.9%	85 min	1.54%	B
JetBlue Airways, whole network	234,468	72.7%	76 min	2.56%	C

Across the year

B6 2120 quarter by quarter

Quarter by quarter B6 2120 held fairly steady: 89.1% in Jul–Sep 2025, 84.6% in Oct–Dec 2025, 80.5% in Jan–Mar 2026 and 84.6% 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 202592 flights89.1%
Oct–Dec 202591 flights84.6%
Jan–Mar 202690 flights80.5%
Apr–Jun 202691 flights84.6%

Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, B6 2120 did best on Wednesday at 92.3% on time and worst on Sunday at 76.0%. Each day rests on about 52 flights, so a gap of 16 points is worth noticing but could still narrow in another year.

Delay causes

Why B6 2120 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 45% of the 6,166 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
30%
Extreme weather
19%
National Airspace System
5%

Extreme weather accounts for 19% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.1 times the usual weather exposure. The split is drawn from 6,166 delay minutes reported on B6 2120.

Cancellations are rare at 0.82%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and routes

What a delay on this flight costs

7.5% 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 close to two hours, which a normal layover absorbs.

At 2,588 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 2120 in the data flew SAN to BOS. 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 2120

For a booking, read B6 2120 as 84.8% on time with 0.82% 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures