Flight number record
DL 840
Delta Air Lines · Denver to Atlanta
- Route
- DEN → ATL
- Departs
- 16:43
- Flights
- 317
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s DL 840, check with Delta Air Lines.
DL 840 lands a B, 4 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That is a workable record, not a spotless one. That rests on 317 flights, with a median arrival 15 minutes early.
Key figures
On time
81.4%
Arrivals under 15 minutes late, of 312 completed flights
Avg delay
113 min
Across delayed arrivals only, not all flights
Cancelled
1.58%
National rate is 1.81%
1 hour+ late
9.0%
National rate is 8.1%
These figures cover 317 flights between July 2025 and June 2026. Beyond the headline rate, 9.0% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When DL 840 flies
DL 840 flies DEN to ATL without a single fixed slot. Its most common scheduled departure was 16:43, used on 86 of 317 flights, with 16:44 (40 flights) and 16:37 (35 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 16:4386 flights27.1%
- Departs 16:4440 flights12.6%
- Departs 16:3735 flights11.0%
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 16:43 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and DL 840 runs 9 points better at 81.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Against the route
DL 840 next to DEN to ATL
Every carrier on DEN to ATL combined arrived on time 80.0% of the time across 5,596 flights, so DL 840 is about level with it. Delta flew 2,805 flights on the same city pair under all its flight numbers, including this one, and those ran 86.3% on time. Across its whole network Delta Air Lines managed 81.6%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 840thin sample | 317 | 81.4% | 113 min | 1.58% | B |
| All Delta Air Lines on DEN–ATL | 2,805 | 86.3% | 71 min | 1.07% | A |
| All carriers on DEN–ATL | 5,596 | 80.0% | 62 min | 0.86% | B+ |
| Delta Air Lines, whole network | 1,038,570 | 81.6% | 71 min | 1.62% | B |
Across the year
DL 840 quarter by quarter
DL 840 did not run the same all year. Its best quarter was Jan–Mar 2026 at 89.2% on time and its weakest Jul–Sep 2025 at 71.7%, a swing of 18 points on roughly 79 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 flights71.7%
- Oct–Dec 202579 flights84.6%
- Jan–Mar 202686 flights89.2%
- Apr–Jun 202660 flights81.4%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
By weekday, DL 840 did best on Wednesday at 93.5% on time and worst on Sunday at 72.1%. Each day rests on about 45 flights, so a gap of 21 points is worth noticing but could still narrow in another year.
Delay causes
Why DL 840 runs late
One category carries most of the weight here. Late-arriving aircraft accounts for 55% of the 6,538 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.
- 55%Late-arriving aircraft
- 34%Carrier
- 8%National Airspace System
- 4%Extreme weather
55% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 6,538 reported delay minutes here, that single category outweighs weather by 15 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 6,538 delay minutes reported on DL 840.
Cancellations sit at 1.58% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.0% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 1,199 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The same number turns up on two other city pairs in the data, including ATL to DEN (91) and TPA to LGA (16), but none flew often enough under DL 840 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DEN to ATL only.
One caution: this is a thin sample. 317 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 840
For a booking, read DL 840 as 81.4% on time with 1.58% cancelled over 317 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- DEN to ATL, every carrier and departure
- ATL to DEN, the return direction
- Delta Air Lines 341 on the same route92.8%
- Delta Air Lines 431 on the same route91.6%
- United Airlines 1305 on the same route69.4%
- Delta Air Lines 346 on the same route80.2%
- Frontier Airlines 3600 on the same route78.7%
- Delta Air Lines 995 on the same route86.8%
- Denver International (DEN) 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
- Why the first flight of the morning is statistically safest
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.