Flight number record

DL 1859

Delta Air Lines · New York to San Juan

Route: JFK → SJU
Departs: 18:55
Flights: 359
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1859, check with Delta Air Lines.

DL 1859 sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 359 flights, with a median arrival 1 minute early.

The national on-time rate over the same period is 77.6%, so DL 1859 runs 9 points behind the country as a whole. Across a thousand flights that is about 88 extra late arrivals.

On time

68.8%

Arrivals under 15 minutes late, of 352 completed flights

Avg delay

59 min

Across delayed arrivals only, not all flights

Cancelled

1.95%

National rate is 1.81%

1 hour+ late

9.7%

National rate is 8.1%

These figures cover 359 flights between July 2025 and June 2026. Beyond the headline rate, 9.7% 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 1859 flies

DL 1859 flies JFK to SJU without a single fixed slot. Its most common scheduled departure was 18:55, used on 67 of 359 flights, with 19:25 (55 flights) and 19:30 (41 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 18:5567 flights18.7%
Departs 19:2555 flights15.3%
Departs 19:3041 flights11.4%

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 18:55 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and DL 1859 runs level with that at 68.8%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

DL 1859 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 1859 is 2 points behind 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%, which this flight trails by 13 points.

DL 1859 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1859thin sample	359	68.8%	59 min	1.95%	C
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 1859 quarter by quarter

DL 1859 did not run the same all year. Its best quarter was Apr–Jun 2026 at 74.7% on time and its weakest Oct–Dec 2025 at 63.7%, a swing of 11 points on roughly 90 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 flights67.8%
Oct–Dec 202592 flights63.7%
Jan–Mar 202684 flights68.8%
Apr–Jun 202691 flights74.7%

Scale runs 55% to 80%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1859 did best on Friday at 80.4% on time and worst on Thursday at 53.8%. Each day rests on about 51 flights, so a gap of 27 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1859 runs late

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 6,468 reported delay minutes.

Carrier
42%
National Airspace System
35%
Late-arriving aircraft
21%
Extreme weather
3%

35% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,237 minutes out of 6,468, against a national NAS share of 21%. The split is drawn from 6,468 delay minutes reported on DL 1859.

Cancellations sit at 1.95% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

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. 9.7% 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 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.

Every one of the 359 flights under DL 1859 in the data flew JFK to SJU. 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. 359 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 DL 1859

For a booking, read DL 1859 as 68.8% on time with 1.95% cancelled over 359 flights. Those are rates from the past twelve months, not a forecast for any particular day.

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