Flight number record

DL 1666

Delta Air Lines · Memphis to Atlanta

Route: MEM → ATL
Departs: 06:00
Flights: 363
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 13 points better than the national rate of 77.6%. When something does go wrong the average delay runs close to two hours. That rests on 363 flights, with a median arrival 17 minutes early.

Set against the rest of the country, DL 1666's record is 13 points better than the US average of 77.6%. That gap is worth roughly 134 fewer late arrivals for every thousand flights.

On time

91.0%

Arrivals under 15 minutes late, of 354 completed flights

Avg delay

104 min

Across delayed arrivals only, not all flights

Cancelled

2.20%

National rate is 1.81%

1 hour+ late

4.5%

National rate is 8.1%

These figures cover 363 flights between July 2025 and June 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.

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 363 flights, with 05:20 (95 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 06:00190 flights52.3%
Departs 05:2095 flights26.2%

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 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 91.0%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

DL 1666 next to MEM to ATL

Every carrier on MEM to ATL combined arrived on time 87.4% of the time across 3,389 flights, so DL 1666 is 4 points ahead of it. Delta flew 3,306 flights on the same city pair under all its flight numbers, including this one, and those ran 87.9% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight beats by 9 points.

DL 1666 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1666thin sample	363	91.0%	104 min	2.20%	A
All Delta Air Lines on MEM–ATL	3,306	87.9%	90 min	1.94%	A
All carriers on MEM–ATL	3,389	87.4%	89 min	2.01%	A
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1666 quarter by quarter

DL 1666 did not run the same all year. Its best quarter was Oct–Dec 2025 at 96.7% on time and its weakest Apr–Jun 2026 at 86.5%, a swing of 10 points on roughly 91 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 202590 flights93.3%
Oct–Dec 202592 flights96.7%
Jan–Mar 202690 flights87.1%
Apr–Jun 202691 flights86.5%

Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1666 ranged from 84.6% on Wednesday to 95.9% on Sunday. With about 52 flights behind each day, a spread of 11 points is inside normal variation, so the day you fly is not worth changing for this flight.

Delay causes

Why DL 1666 runs late

One category carries most of the weight here. Carrier accounts for 76% of the 3,322 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.

Carrier
76%
National Airspace System
14%
Late-arriving aircraft
6%
Extreme weather
4%

The largest share of delay minutes, 76%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 2,538 of the 3,322 delay minutes reported here. The split is drawn from 3,322 delay minutes reported on DL 1666.

Cancellations sit at 2.20% against a national 1.81%, which is ordinary. Diversions add another 0.28%.

Connections and routes

What a delay on this flight costs

Badly late arrivals are rare here: only 4.5% land an hour or more behind schedule, against 8.1% 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.

Every one of the 363 flights under DL 1666 in the data flew MEM to ATL. 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. 363 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 91.0% on time with 2.20% cancelled over 363 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