Flight number record
DL 660
Delta Air Lines · Atlanta to Salt Lake City
- Route
- ATL → SLC
- Departs
- 19:30
- Flights
- 361
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 660, check with Delta Air Lines.
DL 660 sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 361 flights, with a median arrival 5 minutes early.
Key figures
On time
75.0%
Arrivals under 15 minutes late, of 360 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.28%
National rate is 1.89%
1 hour+ late
8.3%
National rate is 8.3%
These figures cover 361 flights between September 2025 and August 2026. Beyond the headline rate, 8.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When DL 660 flies
DL 660 flies ATL to SLC without a single fixed slot. Its most common scheduled departure was 19:30, used on 67 of 361 flights, with 19:45 (62 flights) and 19:34 (55 flights) next.
- Departs 19:3067 flights18.6%
- Departs 19:4562 flights17.2%
- Departs 19:3455 flights15.2%
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 19:30 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and DL 660 runs 7 points better at 75.0%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
DL 660 next to ATL to SLC
Every carrier on ATL to SLC combined arrived on time 82.7% of the time across 2,965 flights, so DL 660 is 8 points behind it. Delta flew 2,959 flights on the same city pair under all its flight numbers, including this one, and those ran 82.7% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 6 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 660thin sample | 361 | 75.0% | 58 min | 0.28% | B+ |
| All Delta Air Lines on ATL–SLC | 2,959 | 82.7% | 60 min | 0.44% | B+ |
| All carriers on ATL–SLC | 2,965 | 82.7% | 60 min | 0.44% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 660 quarter by quarter
DL 660 did not run the same all year. Its best quarter was Jan–Mar 2026 at 84.3% on time and its weakest Jul–Sep 2026 at 59.7%, a swing of 25 points on roughly 72 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 flights76.7%
- Oct–Dec 202588 flights71.6%
- Jan–Mar 202690 flights84.3%
- Apr–Jun 202691 flights79.1%
- Jul–Sep 202662 flights59.7%
Scale runs 50% to 90%.
By weekday, DL 660 did best on Tuesday at 82.7% on time and worst on Friday at 69.4%. Each day rests on about 52 flights, so a gap of 13 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 660 runs when it is late
DL 660 often beats the schedule: 93 of 360 completed flights, 26%, arrived 15 minutes or more early. The 90 late arrivals split 26 under half an hour, 34 between 30 and 60 minutes, and 30 an hour or more.
- 15+ min early93 flights25.8%
- Within 15 min177 flights49.2%
- 15–29 min late26 flights7.2%
- 30–59 min late34 flights9.4%
- 1–2 hours late23 flights6.4%
- 2+ hours late7 flights1.9%
Scale runs 0% to 100%.
Share of 360 completed flights by arrival against schedule.
22 of 99 late departures made up the time and arrived on time, 22% of them. 13 flights left on time and still arrived late.
The worst days
Worst days for DL 660
The latest arrival of the period was on 11 July 2026, 3 hours 57 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. Four of the five worst days fell in July 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 11 July 2026 | 3 hours 57 minutes | Late-arriving aircraft |
| 6 November 2025 | 3 hours 56 minutes | Late-arriving aircraft |
| 24 July 2026 | 3 hours 41 minutes | Carrier |
| 6 July 2026 | 2 hours 39 minutes | Carrier |
| 17 July 2026 | 2 hours 33 minutes | Late-arriving aircraft |
Delay causes
Why DL 660 runs late
Carrier accounts for 52% of the 5,238 delay minutes carriers reported here, and the remaining four split what is left.
- 52%Carrier
- 31%Late-arriving aircraft
- 14%National Airspace System
- 3%Extreme weather
The largest share of delay minutes, 52%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,729 of the 5,238 delay minutes reported here. The split is drawn from 5,238 delay minutes reported on DL 660.
Cancellations are rare at 0.28%, 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
8.3% 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 1,590 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 361 flights under DL 660 in the data flew ATL to SLC. 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. 361 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 660
For a booking, DL 660 is one of the weaker ways to fly ATL to SLC: 8 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.
Related
Where to go next
- ATL to SLC, every carrier and departure
- SLC to ATL, the return direction
- Delta Air Lines 663 on the same route87.9%
- Delta Air Lines 830 on the same route87.8%
- Delta Air Lines 387 on the same route90.3%
- Delta Air Lines 423 on the same route85.6%
- Delta Air Lines 653 on the same route79.4%
- Delta Air Lines 526 on the same route79.6%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Salt Lake City International (SLC) 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
- The best time of day to fly, according to 7.05 million flight records
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.