Flight number record

DL 1966

Delta Air Lines · New York to San Juan

Route: JFK → SJU
Departs: 08:00
Flights: 304
Period: September 2025 to August 2026

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

DL 1966 lands a B−, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 304 flights, with a median arrival 12 minutes early.

On time

80.5%

Arrivals under 15 minutes late, of 292 completed flights

Avg delay

55 min

Across delayed arrivals only, not all flights

Cancelled

3.62%

National rate is 1.89%

1 hour+ late

5.8%

National rate is 8.3%

These figures cover 304 flights between September 2025 and August 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.

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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 150 of 304 flights, with 08:05 (119 flights) and 08:10 (35 flights) next.

Departs 08:00150 flights49.3%
Departs 08:05119 flights39.1%
Departs 08:1035 flights11.5%

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 08:00 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and DL 1966 runs 3 points worse at 80.5%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

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Against the route

DL 1966 next to JFK to SJU

Every carrier on JFK to SJU combined arrived on time 70.2% of the time across 3,554 flights, so DL 1966 is 10 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 77.4% on time. Across its whole network Delta Air Lines managed 81.1%, 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	80.5%	55 min	3.62%	B−
All Delta Air Lines on JFK–SJU	1,104	77.4%	61 min	2.26%	B
All carriers on JFK–SJU	3,554	70.2%	78 min	3.57%	C−
Delta Air Lines, whole network	1,039,517	81.1%	71 min	1.74%	B

Across the year

DL 1966 quarter by quarter

DL 1966 did not run the same all year. Its best quarter was Jul–Sep 2025 at 90.0% on time and its weakest Jul–Sep 2026 at 73.3%, a swing of 17 points on roughly 76 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 flights90.0%
Oct–Dec 202531 flights—
Jan–Mar 202690 flights78.6%
Apr–Jun 202691 flights85.4%
Jul–Sep 202662 flights73.3%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1966 did best on Friday at 90.5% on time and worst on Sunday at 73.2%. Each day rests on about 43 flights, so a gap of 17 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late DL 1966 runs when it is late

DL 1966 often beats the schedule: 124 of 292 completed flights, 42%, arrived 15 minutes or more early. The 57 late arrivals split 21 under half an hour, 19 between 30 and 60 minutes, and 17 an hour or more.

15+ min early124 flights42.5%
Within 15 min111 flights38.0%
15–29 min late21 flights7.2%
30–59 min late19 flights6.5%
1–2 hours late11 flights3.8%
2+ hours late6 flights2.1%

Scale runs 0% to 100%.

Share of 292 completed flights by arrival against schedule.

7 of 36 late departures made up the time and arrived on time, 19% of them. In the other direction, 28 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SJU.

The worst days

Worst days for DL 1966

The latest arrival of the period was on 22 July 2026, 3 hours 28 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.

The latest arrivals of DL 1966 in the period
Date	Arrived late by	Largest filed cause
22 July 2026	3 hours 28 minutes	Carrier
27 January 2026	3 hours 25 minutes	Carrier
26 February 2026	2 hours 41 minutes	Carrier
9 August 2026	2 hours 36 minutes	Carrier
3 August 2026	2 hours 33 minutes	National Airspace System

Delay causes

Why DL 1966 runs late

Carrier accounts for 47% of the 3,153 delay minutes carriers reported here, and the remaining four split what is left.

Carrier
47%
National Airspace System
46%
Late-arriving aircraft
5%
Extreme weather
2%

The largest share of delay minutes, 47%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,492 of the 3,153 delay minutes reported here. The split is drawn from 3,153 delay minutes reported on DL 1966.

Cancellations run at 3.62%, against 1.89% nationally. That is about 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

5.8% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.

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, 83.6% 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	83.6%	70 min	2.28%	B

What to do with this

Booking DL 1966

For a booking, the cancellation rate is the figure to plan around on DL 1966: 3.62% of its 304 scheduled flights did not operate. A late arrival costs about an hour, 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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures