Flight number record
B6 2120
JetBlue Airways · San Diego to Boston
- Route
- SAN → BOS
- Departs
- 20:40
- Flights
- 364
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s B6 2120, check with JetBlue Airways.
B6 2120 lands a B, 4 points better than the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That rests on 364 flights, with a median arrival 17 minutes early.
Set against the rest of the country, B6 2120's record is 4 points better than the US average of 77.3%. That gap is worth roughly 44 fewer late arrivals for every thousand flights.
Key figures
On time
81.7%
Arrivals under 15 minutes late, of 360 completed flights
Avg delay
105 min
Across delayed arrivals only, not all flights
Cancelled
1.10%
National rate is 1.89%
1 hour+ late
9.7%
National rate is 8.3%
These figures cover 364 flights between September 2025 and August 2026. Beyond the headline rate, 9.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When B6 2120 flies
B6 2120 flies SAN to BOS without a single fixed slot. Its most common scheduled departure was 20:40, used on 82 of 364 flights, with 20:44 (48 flights) and 20:55 (46 flights) next.
- Departs 20:4082 flights22.5%
- Departs 20:4448 flights13.2%
- Departs 20:5546 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 20:40 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and B6 2120 runs 12 points better at 81.7%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
B6 2120 next to SAN to BOS
Every carrier on SAN to BOS combined arrived on time 75.5% of the time across 1,881 flights, so B6 2120 is 6 points ahead of it. JetBlue flew 919 flights on the same city pair under all its flight numbers, including this one, and those ran 76.6% on time. Across its whole network JetBlue Airways managed 71.3%, which this flight beats by 10 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| B6 2120thin sample | 364 | 81.7% | 105 min | 1.10% | B |
| All JetBlue Airways on SAN–BOS | 919 | 76.6% | 92 min | 2.07% | B |
| All carriers on SAN–BOS | 1,881 | 75.5% | 84 min | 1.70% | B |
| JetBlue Airways, whole network | 240,615 | 71.3% | 77 min | 3.56% | C− |
Across the year
B6 2120 quarter by quarter
B6 2120 did not run the same all year. Its best quarter was Jul–Sep 2025 at 86.7% on time and its weakest Jul–Sep 2026 at 72.1%, a swing of 15 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 flights86.7%
- Oct–Dec 202591 flights84.6%
- Jan–Mar 202690 flights80.5%
- Apr–Jun 202691 flights84.6%
- Jul–Sep 202662 flights72.1%
Scale runs 65% to 90%.
By weekday, B6 2120 did best on Wednesday at 92.3% on time and worst on Thursday at 74.0%. 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 2120 runs when it is late
B6 2120 often beats the schedule: 189 of 360 completed flights, 53%, arrived 15 minutes or more early. When B6 2120 is late it tends to be very late: 35 of its 66 late arrivals were an hour or more behind, and 9 were two hours or more.
- 15+ min early189 flights52.5%
- Within 15 min105 flights29.2%
- 15–29 min late9 flights2.5%
- 30–59 min late22 flights6.1%
- 1–2 hours late26 flights7.2%
- 2+ hours late9 flights2.5%
Scale runs 0% to 100%.
Share of 360 completed flights by arrival against schedule.
A late pushback is often recovered here: of 91 departures that left 15 minutes late or more, 31 still arrived on time. Only 6 left on time and still arrived late.
The worst days
Worst days for B6 2120
The latest arrival of the period was on 17 September 2025, 15 hours 1 minute behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across September, March, October, January and November, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 17 September 2025 | 15 hours 1 minute | Late-arriving aircraft |
| 8 March 2026 | 14 hours 22 minutes | Extreme weather |
| 13 October 2025 | 13 hours 51 minutes | Carrier |
| 2 January 2026 | 3 hours 38 minutes | Carrier |
| 20 November 2025 | 3 hours 36 minutes | Extreme weather |
Delay causes
Why B6 2120 runs late
Late-arriving aircraft accounts for 51% of the 6,932 delay minutes carriers reported here, and the remaining four split what is left.
- 51%Late-arriving aircraft
- 27%Carrier
- 17%Extreme weather
- 5%National Airspace System
Extreme weather accounts for 17% 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 2.9 times the usual weather exposure. The split is drawn from 6,932 delay minutes reported on B6 2120.
Cancellations sit at 1.10% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
9.7% 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 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 81.7% on time with 1.10% cancelled over 364 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SAN to BOS, every carrier and departure
- BOS to SAN, the return direction
- Alaska Airlines 390 on the same route76.5%
- JetBlue Airways 620 on the same route75.5%
- San Diego International (SAN) delay statistics
- Boston Logan International (BOS) delay statistics
- JetBlue Airways on-time record
- Every JetBlue Airways flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
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 ; recomputed monthly. How this data is collected.