Flight number record
DL 517
Delta Air Lines · Atlanta to San Francisco
- Route
- ATL → SFO
- Departs
- 16:59
- Flights
- 302
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 517, check with Delta Air Lines.
DL 517 draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about 55 minutes behind schedule. Build slack into anything you connect to. That rests on 302 flights, with a median arrival 3 minutes late.
The national on-time rate over the same period is 77.3%, so DL 517 runs 12 points behind the country as a whole. Across a thousand flights that is about 119 extra late arrivals.
Key figures
On time
65.4%
Arrivals under 15 minutes late, of 301 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.33%
National rate is 1.89%
1 hour+ late
9.3%
National rate is 8.3%
These figures cover 302 flights between September 2025 and August 2026. Beyond the headline rate, 9.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When DL 517 flies
DL 517 flies ATL to SFO without a single fixed slot. Its most common scheduled departure was 16:59, used on 56 of 302 flights, with 16:53 (35 flights) next.
- Departs 16:5956 flights18.5%
- Departs 16:5335 flights11.6%
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 16:59 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and DL 517 runs 7 points worse at 65.4%. 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 517 next to ATL to SFO
Every carrier on ATL to SFO combined arrived on time 69.9% of the time across 3,339 flights, so DL 517 is 5 points behind it. Delta flew 2,393 flights on the same city pair under all its flight numbers, including this one, and those ran 68.5% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 16 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 517thin sample | 302 | 65.4% | 55 min | 0.33% | C+ |
| All Delta Air Lines on ATL–SFO | 2,393 | 68.5% | 55 min | 0.67% | C+ |
| All carriers on ATL–SFO | 3,339 | 69.9% | 58 min | 0.69% | C+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 517 quarter by quarter
DL 517 did not run the same all year. Its best quarter was Jan–Mar 2026 at 83.5% on time and its weakest Jul–Sep 2026 at 48.4%, a swing of 35 points on roughly 60 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 flights73.3%
- Oct–Dec 202533 flights60.6%
- Jan–Mar 202686 flights83.5%
- Apr–Jun 202691 flights59.3%
- Jul–Sep 202662 flights48.4%
Scale runs 40% to 90%.
By weekday, DL 517 did best on Tuesday at 79.5% on time and worst on Sunday at 46.5%. Each day rests on about 43 flights, so a gap of 33 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 517 runs when it is late
The 104 late arrivals split 38 under half an hour, 38 between 30 and 60 minutes, and 28 an hour or more.
- 15+ min early48 flights15.9%
- Within 15 min149 flights49.5%
- 15–29 min late38 flights12.6%
- 30–59 min late38 flights12.6%
- 1–2 hours late18 flights6.0%
- 2+ hours late10 flights3.3%
Scale runs 0% to 100%.
Share of 301 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 78 departures that left 15 minutes late or more, only 9 made it up before arrival. In the other direction, 35 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 517
The latest arrival of the period was on 28 April 2026, 4 hours 6 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. On three of the five worst days the largest share was filed as national airspace system delay.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 28 April 2026 | 4 hours 6 minutes | Late-arriving aircraft |
| 12 July 2026 | 3 hours 50 minutes | National Airspace System |
| 11 July 2026 | 3 hours 37 minutes | National Airspace System |
| 4 November 2025 | 3 hours 23 minutes | Carrier |
| 11 August 2026 | 3 hours 23 minutes | National Airspace System |
Delay causes
Why DL 517 runs late
National Airspace System accounts for 51% of the 5,672 delay minutes carriers reported here, and the remaining four split what is left.
- 51%National Airspace System
- 34%Carrier
- 12%Late-arriving aircraft
- 4%Extreme weather
The largest share of delay minutes, 34%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,929 of the 5,672 delay minutes reported here. The split is drawn from 5,672 delay minutes reported on DL 517.
Cancellations are rare at 0.33%, below the national 1.89% 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
9.3% 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 2,139 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.
The same number turns up on three other city pairs in the data, including SFO to ATL (58), DFW to ATL (18) and LAX to BNA (16), but none flew often enough under DL 517 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ATL to SFO only.
One caution: this is a thin sample. 302 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 517
For a booking, read DL 517 as 65.4% on time with 0.33% cancelled over 302 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- ATL to SFO, every carrier and departure
- SFO to ATL, the return direction
- Delta Air Lines 823 on the same route64.8%
- Delta Air Lines 693 on the same route81.2%
- Delta Air Lines 656 on the same route71.8%
- Hartsfield-Jackson Atlanta International (ATL) 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.