Flight number record
DL 679
Delta Air Lines · New York to San Francisco
- Route
- JFK → SFO
- Departs
- 14:55
- Flights
- 346
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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 C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 346 flights, with a median arrival 5 minutes early.
The national on-time rate over the same period is 77.3%, so DL 679 runs 5 points behind the country as a whole. Across a thousand flights that is about 46 extra late arrivals.
Key figures
On time
72.7%
Arrivals under 15 minutes late, of 341 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
1.16%
National rate is 1.89%
1 hour+ late
11.4%
National rate is 8.3%
These figures cover 346 flights between September 2025 and August 2026. Beyond the headline rate, 11.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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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 127 of 346 flights, with 14:59 (57 flights) next.
- Departs 14:55127 flights36.7%
- Departs 14:5957 flights16.5%
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 14:55 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and DL 679 runs level with that at 72.7%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
DL 679 next to JFK to SFO
Every carrier on JFK to SFO combined arrived on time 71.4% of the time across 6,800 flights, so DL 679 is about level with it. Delta flew 2,231 flights on the same city pair under all its flight numbers, including this one, and those ran 67.3% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 8 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 679thin sample | 346 | 72.7% | 73 min | 1.16% | C |
| All Delta Air Lines on JFK–SFO | 2,231 | 67.3% | 70 min | 2.20% | C |
| All carriers on JFK–SFO | 6,800 | 71.4% | 69 min | 2.57% | C |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 679 quarter by quarter
DL 679 did not run the same all year. Its best quarter was Jul–Sep 2026 at 77.8% on time and its weakest Oct–Dec 2025 at 64.4%, a swing of 13 points on roughly 87 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 202527 flights—
- Oct–Dec 202587 flights64.4%
- Jan–Mar 202687 flights76.5%
- Apr–Jun 202688 flights72.7%
- Jul–Sep 202657 flights77.8%
Scale runs 55% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, DL 679 did best on Monday at 78.8% on time and worst on Saturday at 62.5%. Each day rests on about 49 flights, so a gap of 16 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 679 runs when it is late
DL 679 often beats the schedule: 117 of 341 completed flights, 34%, arrived 15 minutes or more early. The 93 late arrivals split 26 under half an hour, 28 between 30 and 60 minutes, and 39 an hour or more.
- 15+ min early117 flights34.3%
- Within 15 min131 flights38.4%
- 15–29 min late26 flights7.6%
- 30–59 min late28 flights8.2%
- 1–2 hours late23 flights6.7%
- 2+ hours late16 flights4.7%
Scale runs 0% to 100%.
Share of 341 completed flights by arrival against schedule.
22 of 78 late departures made up the time and arrived on time, 28% of them. In the other direction, 37 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 SFO.
The worst days
Worst days for DL 679
The latest arrival of the period was on 18 January 2026, 4 hours 21 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.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 18 January 2026 | 4 hours 21 minutes | Carrier |
| 20 December 2025 | 4 hours 9 minutes | Carrier |
| 19 June 2026 | 3 hours 39 minutes | Late-arriving aircraft |
| 1 April 2026 | 3 hours 34 minutes | Carrier |
| 18 November 2025 | 3 hours 28 minutes | Carrier |
Delay causes
Why DL 679 runs late
National Airspace System accounts for 52% of the 6,762 delay minutes carriers reported here, and the remaining four split what is left.
- 52%National Airspace System
- 35%Carrier
- 9%Late-arriving aircraft
- 4%Extreme weather
52% 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 3,503 minutes out of 6,762, against a national NAS share of 21%. The split is drawn from 6,762 delay minutes reported on DL 679.
Cancellations sit at 1.16% against a national 1.89%, which is ordinary. Diversions add another 0.29%.
Connections and routes
What a delay on this flight costs
11.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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 346 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. 346 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 72.7% on time with 1.16% cancelled over 346 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- JFK to SFO, every carrier and departure
- SFO to JFK, the return direction
- American Airlines 179 on the same route79.8%
- American Airlines 177 on the same route60.4%
- Delta Air Lines 668 on the same route71.8%
- Delta Air Lines 667 on the same route55.7%
- American Airlines 15 on the same route73.7%
- JetBlue Airways 115 on the same route80.9%
- John F. Kennedy International (JFK) delay statistics
- San Francisco International (SFO) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- How often a connection fails at the major US hubs
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 ; recomputed monthly. How this data is collected.