Flight number record
DL 1666
Delta Air Lines · Memphis to Atlanta
- Route
- MEM → ATL
- Departs
- 06:00
- Flights
- 336
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1666, check with Delta Air Lines.
DL 1666 earns an A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 14 points better than the national rate of 77.3%. When something does go wrong the average delay runs close to two hours. That rests on 336 flights, with a median arrival 17 minutes early.
Set against the rest of the country, DL 1666's record is 14 points better than the US average of 77.3%. That gap is worth roughly 139 fewer late arrivals for every thousand flights.
Key figures
On time
91.2%
Arrivals under 15 minutes late, of 328 completed flights
Avg delay
107 min
Across delayed arrivals only, not all flights
Cancelled
2.08%
National rate is 1.89%
1 hour+ late
4.3%
National rate is 8.3%
These figures cover 336 flights between September 2025 and August 2026. The median arrival is 17 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Schedule
When DL 1666 flies
DL 1666 flies MEM to ATL without a single fixed slot. Its most common scheduled departure was 06:00, used on 190 of 336 flights, with 05:15 (57 flights) and 05:20 (35 flights) next.
- Departs 06:00190 flights56.5%
- Departs 05:1557 flights17.0%
- Departs 05:2035 flights10.4%
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 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 1666 runs level with that at 91.2%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Against the route
DL 1666 next to MEM to ATL
Every carrier on MEM to ATL combined arrived on time 86.2% of the time across 3,432 flights, so DL 1666 is 5 points ahead of it. Delta flew 3,348 flights on the same city pair under all its flight numbers, including this one, and those ran 86.7% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 10 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1666thin sample | 336 | 91.2% | 107 min | 2.08% | A |
| All Delta Air Lines on MEM–ATL | 3,348 | 86.7% | 94 min | 1.85% | A |
| All carriers on MEM–ATL | 3,432 | 86.2% | 93 min | 1.92% | A |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1666 quarter by quarter
DL 1666 did not run the same all year. Its best quarter was Jul–Sep 2025 at 96.7% on time and its weakest Apr–Jun 2026 at 86.5%, a swing of 10 points on roughly 67 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 flights96.7%
- Oct–Dec 202592 flights96.7%
- Jan–Mar 202690 flights87.1%
- Apr–Jun 202691 flights86.5%
- Jul–Sep 202633 flights93.9%
Scale runs 80% to 100%.
By weekday, DL 1666 ranged from 85.4% on Wednesday to 95.6% on Sunday. With about 48 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late DL 1666 runs when it is late
DL 1666 often beats the schedule: 181 of 328 completed flights, 55%, arrived 15 minutes or more early. The 29 late arrivals split 9 under half an hour, 6 between 30 and 60 minutes, and 14 an hour or more.
- 15+ min early181 flights55.2%
- Within 15 min118 flights36.0%
- 15–29 min late9 flights2.7%
- 30–59 min late6 flights1.8%
- 1–2 hours late5 flights1.5%
- 2+ hours late9 flights2.7%
Scale runs 0% to 100%.
Share of 328 completed flights by arrival against schedule.
4 of 21 late departures made up the time and arrived on time, 19% of them. 12 flights left on time and still arrived late.
The worst days
Worst days for DL 1666
The latest arrival of the period was on 28 April 2026, 8 hours 22 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on five of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 28 April 2026 | 8 hours 22 minutes | Carrier |
| 9 April 2026 | 6 hours 8 minutes | Carrier |
| 7 November 2025 | 4 hours 58 minutes | Carrier |
| 18 March 2026 | 4 hours 45 minutes | Carrier |
| 20 May 2026 | 3 hours 26 minutes | Carrier |
Delay causes
Why DL 1666 runs late
Carrier accounts for 81% of the 3,101 delay minutes carriers reported here, and the remaining four split what is left.
- 81%Carrier
- 14%National Airspace System
- 4%Extreme weather
The largest share of delay minutes, 81%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,523 of the 3,101 delay minutes reported here. The split is drawn from 3,101 delay minutes reported on DL 1666.
Cancellations sit at 2.08% against a national 1.89%, which is ordinary. Diversions add another 0.30%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 4.3% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The same number turns up on two other city pairs in the data, including ATL to JAN (29) and JAN to ATL (29), but none flew often enough under DL 1666 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to MEM to ATL only.
One caution: this is a thin sample. 336 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 1666
For a booking, read DL 1666 as 91.2% on time with 2.08% cancelled over 336 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- MEM to ATL, every carrier and departure
- ATL to MEM, the return direction
- Delta Air Lines 1624 on the same route89.9%
- Delta Air Lines 2778 on the same route84.9%
- Delta Air Lines 1700 on the same route78.9%
- Delta Air Lines 1625 on the same route91.0%
- Delta Air Lines 2071 on the same route92.5%
- Delta Air Lines 82 on the same route88.9%
- Memphis International (MEM) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) 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
- Worst months to fly in the US, ranked by the data
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.