Flight number record

DL 640

Delta Air Lines · San Francisco to Atlanta

Route: SFO → ATL
Departs: 08:00
Flights: 364
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 640, check with Delta Air Lines.

DL 640 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 12 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 364 flights, with a median arrival 12 minutes early.

Set against the rest of the country, DL 640's record is 12 points better than the US average of 77.6%. That gap is worth roughly 122 fewer late arrivals for every thousand flights.

On time

89.8%

Arrivals under 15 minutes late, of 362 completed flights

Avg delay

74 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.81%

1 hour+ late

3.0%

National rate is 8.1%

These figures cover 364 flights between July 2025 and June 2026. The median arrival is 12 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 640 flies

DL 640 flies SFO to ATL without a single fixed slot. Its most common scheduled departure was 08:00, used on 137 of 364 flights, with 07:15 (74 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 08:00137 flights37.6%
Departs 07:1574 flights20.3%

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 08:00 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and DL 640 runs 6 points better at 89.8%. 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 640 next to SFO to ATL

Every carrier on SFO to ATL combined arrived on time 81.6% of the time across 3,350 flights, so DL 640 is 8 points ahead of it. Delta flew 2,407 flights on the same city pair under all its flight numbers, including this one, and those ran 83.0% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight beats by 8 points.

DL 640 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 640thin sample	364	89.8%	74 min	0.55%	A+
All Delta Air Lines on SFO–ATL	2,407	83.0%	68 min	0.66%	B+
All carriers on SFO–ATL	3,350	81.6%	67 min	0.81%	B+
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 640 quarter by quarter

DL 640 did not run the same all year. Its best quarter was Oct–Dec 2025 at 95.6% on time and its weakest Apr–Jun 2026 at 82.4%, a swing of 13 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 202592 flights87.0%
Oct–Dec 202591 flights95.6%
Jan–Mar 202690 flights94.4%
Apr–Jun 202691 flights82.4%

Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, DL 640 ranged from 86.3% on Friday to 92.3% on Sunday. With about 52 flights behind each day, a spread of 6 points is inside normal variation, so the day you fly is not worth changing for this flight.

Delay causes

Why DL 640 runs late

One category carries most of the weight here. Carrier accounts for 65% of the 2,741 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
65%
National Airspace System
19%
Late-arriving aircraft
15%

The largest share of delay minutes, 65%, 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 1,793 of the 2,741 delay minutes reported here. The split is drawn from 2,741 delay minutes reported on DL 640.

Cancellations are rare at 0.55%, below the national 1.81% 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

Badly late arrivals are rare here: only 3.0% 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.

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.

Every one of the 364 flights under DL 640 in the data flew SFO 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. 364 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 640

For a booking, DL 640 has one of the better records a US domestic flight can show: 89.8% on time and 0.55% cancelled. That is a base rate, not a promise about any single 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