Flight number record
B6 1734
JetBlue Airways · San Francisco to Boston
- Route
- SFO → BOS
- Departs
- 08:25
- Flights
- 342
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s B6 1734, check with JetBlue Airways.
B6 1734 sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 342 flights, with a median arrival 6 minutes early.
The national on-time rate over the same period is 77.6%, so B6 1734 runs 7 points behind the country as a whole. Across a thousand flights that is about 70 extra late arrivals.
Key figures
On time
70.6%
Arrivals under 15 minutes late, of 333 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
2.63%
National rate is 1.81%
1 hour+ late
12.0%
National rate is 8.1%
These figures cover 342 flights between July 2025 and June 2026. Beyond the headline rate, 12.0% 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 1734 flies
B6 1734 flies SFO to BOS without a single fixed slot. Its most common scheduled departure was 08:25, used on 64 of 342 flights, with 12:20 (45 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 08:2564 flights18.7%
- Departs 12:2045 flights13.2%
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 08:25 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and B6 1734 runs 14 points worse at 70.6%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Against the route
B6 1734 next to SFO to BOS
Every carrier on SFO to BOS combined arrived on time 76.9% of the time across 4,674 flights, so B6 1734 is 6 points behind it. JetBlue flew 1,674 flights on the same city pair under all its flight numbers, including this one, and those ran 75.4% on time. Across its whole network JetBlue Airways managed 72.7%, which this flight trails by 2 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| B6 1734thin sample | 342 | 70.6% | 65 min | 2.63% | C |
| All JetBlue Airways on SFO–BOS | 1,674 | 75.4% | 76 min | 1.79% | B |
| All carriers on SFO–BOS | 4,674 | 76.9% | 74 min | 1.35% | B |
| JetBlue Airways, whole network | 234,468 | 72.7% | 76 min | 2.56% | C |
Across the year
B6 1734 quarter by quarter
B6 1734 did not run the same all year. Its best quarter was Jul–Sep 2025 at 78.3% on time and its weakest Apr–Jun 2026 at 53.6%, a swing of 25 points on roughly 86 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 202592 flights78.3%
- Oct–Dec 202591 flights69.0%
- Jan–Mar 202690 flights77.6%
- Apr–Jun 202669 flights53.6%
Scale runs 45% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, B6 1734 did best on Saturday at 85.4% on time and worst on Thursday at 54.2%. Each day rests on about 49 flights, so a gap of 31 points is worth noticing but could still narrow in another year.
Delay causes
Why B6 1734 runs late
One category carries most of the weight here. National Airspace System accounts for 54% of the 6,336 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.
- 54%National Airspace System
- 35%Late-arriving aircraft
- 10%Carrier
35% 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 6,336 reported delay minutes here, that single category outweighs weather by 35 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 6,336 delay minutes reported on B6 1734.
Cancellations run at 2.63%, 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. 12.0% 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 2,704 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 342 flights under B6 1734 in the data flew SFO 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. 342 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 1734
For a booking, the cancellation rate is the figure to plan around on B6 1734: 2.63% of its 342 scheduled flights did not operate. A late arrival costs about an hour, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- SFO to BOS, every carrier and departure
- BOS to SFO, the return direction
- Delta Air Lines 400 on the same route89.1%
- United Airlines 1665 on the same route84.7%
- United Airlines 2647 on the same route81.1%
- JetBlue Airways 734 on the same route78.3%
- United Airlines 2356 on the same route61.6%
- JetBlue Airways 434 on the same route85.1%
- San Francisco International (SFO) 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.