Flight number record
DL 840
Delta Air Lines · Denver to Atlanta
- Route
- DEN → ATL
- Departs
- 16:43
- Flights
- 317
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 840, check with Delta Air Lines.
DL 840 lands a B, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 317 flights, with a median arrival 14 minutes early.
Key figures
On time
80.7%
Arrivals under 15 minutes late, of 311 completed flights
Avg delay
78 min
Across delayed arrivals only, not all flights
Cancelled
1.89%
National rate is 1.89%
1 hour+ late
8.7%
National rate is 8.3%
These figures cover 317 flights between September 2025 and August 2026. Beyond the headline rate, 8.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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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 92 of 317 flights, with 16:44 (40 flights) and 16:33 (39 flights) next.
- Departs 16:4392 flights29.0%
- Departs 16:4440 flights12.6%
- Departs 16:3339 flights12.3%
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 16:43 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and DL 840 runs 9 points better at 80.7%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
DL 840 next to DEN to ATL
Every carrier on DEN to ATL combined arrived on time 78.6% of the time across 5,603 flights, so DL 840 is 2 points ahead of it. Delta flew 2,807 flights on the same city pair under all its flight numbers, including this one, and those ran 85.8% on time. Across its whole network Delta Air Lines managed 81.1%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 840thin sample | 317 | 80.7% | 78 min | 1.89% | B |
| All Delta Air Lines on DEN–ATL | 2,807 | 85.8% | 61 min | 1.18% | A |
| All carriers on DEN–ATL | 5,603 | 78.6% | 58 min | 0.93% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | 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 2026 at 63.9%, a swing of 25 points on roughly 63 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 flights80.0%
- Oct–Dec 202579 flights84.6%
- Jan–Mar 202686 flights89.2%
- Apr–Jun 202660 flights81.4%
- Jul–Sep 202662 flights63.9%
Scale runs 55% to 95%.
By weekday, DL 840 did best on Wednesday at 88.9% on time and worst on Sunday at 72.1%. Each day rests on about 45 flights, so a gap of 17 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 840 runs when it is late
DL 840 often beats the schedule: 152 of 311 completed flights, 49%, arrived 15 minutes or more early. The 60 late arrivals split 15 under half an hour, 18 between 30 and 60 minutes, and 27 an hour or more.
- 15+ min early152 flights48.9%
- Within 15 min99 flights31.8%
- 15–29 min late15 flights4.8%
- 30–59 min late18 flights5.8%
- 1–2 hours late16 flights5.1%
- 2+ hours late11 flights3.5%
Scale runs 0% to 100%.
Share of 311 completed flights by arrival against schedule.
A late pushback is often recovered here: of 77 departures that left 15 minutes late or more, 27 still arrived on time. 10 flights left on time and still arrived late.
The worst days
Worst days for DL 840
The latest arrival of the period was on 28 April 2026, 5 hours 27 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 28 April 2026 | 5 hours 27 minutes | Carrier |
| 7 December 2025 | 4 hours 49 minutes | Late-arriving aircraft |
| 8 June 2026 | 4 hours 39 minutes | Late-arriving aircraft |
| 11 September 2025 | 3 hours 53 minutes | Late-arriving aircraft |
| 8 November 2025 | 3 hours 52 minutes | Carrier |
Delay causes
Why DL 840 runs late
Late-arriving aircraft accounts for 57% of the 4,684 delay minutes carriers reported here, and the remaining four split what is left.
- 57%Late-arriving aircraft
- 22%Carrier
- 16%National Airspace System
- 4%Extreme weather
57% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,684 reported delay minutes here, that single category outweighs weather by 13 to one. The split is drawn from 4,684 delay minutes reported on DL 840.
Cancellations sit at 1.89% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
8.7% 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 a little over an hour, which a normal layover absorbs.
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.
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 80.7% on time with 1.89% 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 route93.9%
- Delta Air Lines 431 on the same route93.9%
- United Airlines 1305 on the same route70.9%
- Delta Air Lines 346 on the same route79.2%
- Frontier Airlines 3600 on the same route70.8%
- Frontier Airlines 3294 on the same route87.5%
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.