Flight number record

DL 679

Delta Air Lines · New York to San Francisco

Route: JFK → SFO
Departs: 14:55
Flights: 351
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 679, check with Delta Air Lines.

DL 679 sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 351 flights, with a median arrival 7 minutes early.

On time

75.0%

Arrivals under 15 minutes late, of 348 completed flights

Avg delay

75 min

Across delayed arrivals only, not all flights

Cancelled

0.85%

National rate is 1.81%

1 hour+ late

10.1%

National rate is 8.1%

These figures cover 351 flights between July 2025 and June 2026. Beyond the headline rate, 10.1% 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 679 flies

DL 679 flies JFK to SFO without a single fixed slot. Its most common scheduled departure was 14:55, used on 75 of 351 flights, with 15:20 (69 flights) and 14:59 (57 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 14:5575 flights21.4%
Departs 15:2069 flights19.7%
Departs 14:5957 flights16.2%

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 14:55 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and DL 679 runs 3 points better at 75.0%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

DL 679 next to JFK to SFO

Every carrier on JFK to SFO combined arrived on time 74.1% of the time across 6,730 flights, so DL 679 is about level with it. Delta flew 2,229 flights on the same city pair under all its flight numbers, including this one, and those ran 71.3% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 7 points.

DL 679 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 679thin sample	351	75.0%	75 min	0.85%	B+
All Delta Air Lines on JFK–SFO	2,229	71.3%	70 min	1.48%	C
All carriers on JFK–SFO	6,730	74.1%	71 min	1.92%	C
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 679 quarter by quarter

DL 679 did not run the same all year. Its best quarter was Jul–Sep 2025 at 86.4% on time and its weakest Oct–Dec 2025 at 64.4%, a swing of 22 points on roughly 88 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 202589 flights86.4%
Oct–Dec 202587 flights64.4%
Jan–Mar 202687 flights76.5%
Apr–Jun 202688 flights72.7%

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 679 did best on Friday at 82.7% on time and worst on Thursday at 69.2%. Each day rests on about 50 flights, so a gap of 14 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 679 runs late

One category carries most of the weight here. National Airspace System accounts for 51% of the 6,496 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
36%
Late-arriving aircraft
10%
Extreme weather
3%

51% 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 3,332 minutes out of 6,496, against a national NAS share of 21%. The split is drawn from 6,496 delay minutes reported on DL 679.

Cancellations are rare at 0.85%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

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. 10.1% 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 2,586 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 351 flights under DL 679 in the data flew JFK to SFO. 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. 351 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 679

For a booking, read DL 679 as 75.0% on time with 0.85% cancelled over 351 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