Flight number record

DL 1439

Delta Air Lines · Boston to Tampa

Route: BOS → TPA
Departs: 15:40
Flights: 343
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1439, check with Delta Air Lines.

DL 1439 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 an hour and a half behind schedule. That rests on 343 flights, with a median arrival right on schedule.

The national on-time rate over the same period is 77.6%, so DL 1439 runs 7 points behind the country as a whole. Across a thousand flights that is about 72 extra late arrivals.

On time

70.4%

Arrivals under 15 minutes late, of 334 completed flights

Avg delay

85 min

Across delayed arrivals only, not all flights

Cancelled

2.33%

National rate is 1.81%

1 hour+ late

14.4%

National rate is 8.1%

These figures cover 343 flights between July 2025 and June 2026. Beyond the headline rate, 14.4% 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 DL 1439 flies

DL 1439 flies BOS to TPA without a single fixed slot. Its most common scheduled departure was 15:40, used on 54 of 343 flights, with 16:19 (50 flights) and 15:55 (38 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 15:4054 flights15.7%
Departs 16:1950 flights14.6%
Departs 15:5538 flights11.1%

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 15:40 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and DL 1439 runs 2 points worse at 70.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

DL 1439 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 DL 1439 is 4 points behind it. Delta flew 1,168 flights on the same city pair under all its flight numbers, including this one, and those ran 75.7% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 11 points.

DL 1439 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1439thin sample	343	70.4%	85 min	2.33%	C
All Delta Air Lines on BOS–TPA	1,168	75.7%	78 min	1.97%	B
All carriers on BOS–TPA	2,822	74.8%	71 min	2.48%	C
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1439 quarter by quarter

DL 1439 did not run the same all year. Its best quarter was Apr–Jun 2026 at 82.2% on time and its weakest Jul–Sep 2025 at 56.7%, a swing of 26 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 202590 flights56.7%
Oct–Dec 202582 flights66.7%
Jan–Mar 202680 flights76.3%
Apr–Jun 202691 flights82.2%

Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1439 did best on Wednesday at 88.2% on time and worst on Monday at 64.0%. Each day rests on about 49 flights, so a gap of 24 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1439 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 50% of the 8,417 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
50%
Carrier
32%
National Airspace System
18%
Extreme weather
0%

50% 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 8,417 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 8,417 delay minutes reported on DL 1439.

Cancellations sit at 2.33% against a national 1.81%, which is ordinary. Diversions add another 0.29%.

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. 14.4% 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.

DL 1439 is not only a BOS to TPA flight. It also flew TPA to BOS (300 flights, 69.8% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.

One caution: this is a thin sample. 343 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.

Other routes flown as DL 1439
Also flown as	Flights	On time	Avg delay	Cancelled	Grade
TPA to BOSthin sample	300	69.8%	86 min	2.67%	C

What to do with this

Booking DL 1439

For a booking, DL 1439 is a flight to put a long connection behind. 14.4% 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 Delta Air Lines’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