Flight number record

DL 1966

Delta Air Lines · New York to San Juan

Route: JFK → SJU
Departs: 08:00
Flights: 304
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1966, check with Delta Air Lines.

DL 1966 lands a B, 4 points better than the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about 45 minutes on average. That is a workable record, not a spotless one. That rests on 304 flights, with a median arrival 12 minutes early.

Set against the rest of the country, DL 1966's record is 4 points better than the US average of 77.6%. That gap is worth roughly 40 fewer late arrivals for every thousand flights.

On time

81.6%

Arrivals under 15 minutes late, of 293 completed flights

Avg delay

45 min

Across delayed arrivals only, not all flights

Cancelled

2.96%

National rate is 1.81%

1 hour+ late

3.8%

National rate is 8.1%

These figures cover 304 flights between July 2025 and June 2026. The median arrival is 12 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 DL 1966 flies

DL 1966 flies JFK to SJU without a single fixed slot. Its most common scheduled departure was 08:00, used on 129 of 304 flights, with 08:05 (119 flights) and 08:10 (56 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 08:00129 flights42.4%
Departs 08:05119 flights39.1%
Departs 08:1056 flights18.4%

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 08:00 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and DL 1966 runs 3 points worse at 81.6%. 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

DL 1966 next to JFK to SJU

Every carrier on JFK to SJU combined arrived on time 71.1% of the time across 3,651 flights, so DL 1966 is 11 points ahead of it. Delta flew 1,104 flights on the same city pair under all its flight numbers, including this one, and those ran 78.8% on time. Across its whole network Delta Air Lines managed 81.6%, close to this flight's figure.

DL 1966 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1966thin sample	304	81.6%	45 min	2.96%	B
All Delta Air Lines on JFK–SJU	1,104	78.8%	60 min	1.99%	B
All carriers on JFK–SJU	3,651	71.1%	74 min	2.63%	C
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1966 quarter by quarter

Quarter by quarter DL 1966 held fairly steady: 82.4% in Jul–Sep 2025, 78.6% in Jan–Mar 2026 and 85.4% in Apr–Jun 2026. A spread of 7 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights82.4%
Oct–Dec 202531 flights—
Jan–Mar 202690 flights78.6%
Apr–Jun 202691 flights85.4%

Scale runs 70% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1966 did best on Friday at 92.7% on time and worst on Sunday at 73.8%. Each day rests on about 43 flights, so a gap of 19 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1966 runs late

One category carries most of the weight here. National Airspace System accounts for 51% of the 2,423 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.

National Airspace System
51%
Carrier
45%
Extreme weather
2%
Late-arriving aircraft
2%

The largest share of delay minutes, 45%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 1,099 of the 2,423 delay minutes reported here. The split is drawn from 2,423 delay minutes reported on DL 1966.

Cancellations run at 2.96%, against 1.81% nationally. That is roughly one flight in 30 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

Badly late arrivals are rare here: only 3.8% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

At 1,598 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.

DL 1966 is not only a JFK to SJU flight. It also flew SJU to JFK (263 flights, 85.5% 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. 304 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 1966
Also flown as	Flights	On time	Avg delay	Cancelled	Grade
SJU to JFKthin sample	263	85.5%	70 min	2.28%	A

What to do with this

Booking DL 1966

For a booking, the cancellation rate is the figure to plan around on DL 1966: 2.96% of its 304 scheduled flights did not operate. A late arrival costs about 45 minutes, but a cancellation costs the day, so leave a later option open.

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