Flight number record

B6 391

JetBlue Airways · Boston to Tampa

Route: BOS → TPA
Departs: 16:00
Flights: 321
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s B6 391, check with JetBlue Airways.

B6 391 draws a D. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 321 flights, with a median arrival 1 minute late.

The national on-time rate over the same period is 77.6%, so B6 391 runs 16 points behind the country as a whole. Across a thousand flights that is about 161 extra late arrivals.

On time

61.5%

Arrivals under 15 minutes late, of 312 completed flights

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

2.18%

National rate is 1.81%

1 hour+ late

16.0%

National rate is 8.1%

These figures cover 321 flights between July 2025 and June 2026. Beyond the headline rate, 16.0% 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 391 flies

B6 391 flies BOS to TPA without a single fixed slot. Its most common scheduled departure was 16:00, used on 42 of 321 flights, with 17:10 (36 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 16:0042 flights13.1%
Departs 17:1036 flights11.2%

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 16:00 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and B6 391 runs 11 points worse at 61.5%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

B6 391 next to BOS to TPA

Every carrier on BOS to TPA combined arrived on time 74.8% of the time across 2,822 flights, so B6 391 is 13 points behind it. JetBlue flew 1,576 flights on the same city pair under all its flight numbers, including this one, and those ran 74.1% on time. Across its whole network JetBlue Airways managed 72.7%, which this flight trails by 11 points.

B6 391 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
B6 391thin sample	321	61.5%	68 min	2.18%	D
All JetBlue Airways on BOS–TPA	1,576	74.1%	67 min	2.86%	C
All carriers on BOS–TPA	2,822	74.8%	71 min	2.48%	C
JetBlue Airways, whole network	234,468	72.7%	76 min	2.56%	C

Across the year

B6 391 quarter by quarter

B6 391 did not run the same all year. Its best quarter was Apr–Jun 2026 at 72.7% on time and its weakest Oct–Dec 2025 at 49.3%, a swing of 23 points on roughly 80 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 202568 flights55.4%
Oct–Dec 202574 flights49.3%
Jan–Mar 202690 flights65.1%
Apr–Jun 202689 flights72.7%

Scale runs 40% to 80%. Rows with fewer than 30 flights show a dash.

By weekday, B6 391 did best on Wednesday at 79.1% on time and worst on Sunday at 42.6%. Each day rests on about 46 flights, so a gap of 36 points is worth noticing but could still narrow in another year.

Delay causes

Why B6 391 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 52% of the 8,173 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
52%
Carrier
26%
National Airspace System
20%
Extreme weather
1%

52% 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 8,173 reported delay minutes here, that single category outweighs weather by 50 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 8,173 delay minutes reported on B6 391.

Cancellations sit at 2.18% against a national 1.81%, which is ordinary. Diversions add another 0.62%.

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. 16.0% 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.

The 1,185 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

Every one of the 321 flights under B6 391 in the data flew BOS to TPA. 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. 321 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 391

For a booking, B6 391 is a flight to put a long connection behind. 16.0% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.

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