Flight number record
DL 519
Delta Air Lines · Atlanta to Denver
- Route
- ATL → DEN
- Departs
- 16:35
- Flights
- 365
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s DL 519, check with Delta Air Lines.
DL 519 draws a D+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is roughly 50 minutes behind schedule. Build slack into anything you connect to. That rests on 365 flights, with a median arrival 4 minutes late.
The national on-time rate over the same period is 77.6%, so DL 519 runs 13 points behind the country as a whole. Across a thousand flights that is about 128 extra late arrivals.
Key figures
On time
64.8%
Arrivals under 15 minutes late, of 358 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
0.82%
National rate is 1.81%
1 hour+ late
10.9%
National rate is 8.1%
These figures cover 365 flights between July 2025 and June 2026. Beyond the headline rate, 10.9% 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 519 flies
DL 519 flies ATL to DEN without a single fixed slot. Its most common scheduled departure was 16:35, used on 55 of 365 flights, with 16:00 (46 flights) and 16:30 (45 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 16:3555 flights15.1%
- Departs 16:0046 flights12.6%
- Departs 16:3045 flights12.3%
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 16:35 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and DL 519 runs 8 points worse at 64.8%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Against the route
DL 519 next to ATL to DEN
Every carrier on ATL to DEN combined arrived on time 77.6% of the time across 5,589 flights, so DL 519 is 13 points behind it. Delta flew 2,805 flights on the same city pair under all its flight numbers, including this one, and those ran 78.1% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 17 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 519 | 365 | 64.8% | 51 min | 0.82% | D+ |
| All Delta Air Lines on ATL–DEN | 2,805 | 78.1% | 52 min | 1.11% | B |
| All carriers on ATL–DEN | 5,589 | 77.6% | 60 min | 1.02% | B |
| Delta Air Lines, whole network | 1,038,570 | 81.6% | 71 min | 1.62% | B |
Across the year
DL 519 quarter by quarter
DL 519 did not run the same all year. Its best quarter was Jan–Mar 2026 at 77.0% on time and its weakest Jul–Sep 2025 at 51.7%, a swing of 25 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 flights51.7%
- Oct–Dec 202592 flights63.7%
- Jan–Mar 202690 flights77.0%
- Apr–Jun 202691 flights67.0%
Scale runs 45% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, DL 519 did best on Wednesday at 73.1% on time and worst on Monday at 54.9%. Each day rests on about 52 flights, so a gap of 18 points is worth noticing but could still narrow in another year.
Delay causes
Why DL 519 runs late
One category carries most of the weight here. National Airspace System accounts for 42% of the 6,474 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.
- 42%National Airspace System
- 34%Carrier
- 16%Late-arriving aircraft
- 8%Extreme weather
The largest share of delay minutes, 34%, 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 2,203 of the 6,474 delay minutes reported here. The split is drawn from 6,474 delay minutes reported on DL 519.
Cancellations are rare at 0.82%, 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
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.9% 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 one other city pair in the data, including DEN to ATL (12), but none flew often enough under DL 519 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ATL to DEN only.
One caution: this is a thin sample. 365 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 519
For a booking, DL 519 is one of the weaker ways to fly ATL to DEN: 13 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.
Related
Where to go next
- ATL to DEN, every carrier and departure
- DEN to ATL, the return direction
- United Airlines 235 on the same route80.2%
- Frontier Airlines 3293 on the same route79.2%
- Delta Air Lines 746 on the same route66.3%
- Delta Air Lines 706 on the same route85.5%
- Delta Air Lines 530 on the same route81.6%
- Delta Air Lines 493 on the same route75.4%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Denver International (DEN) 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
- How often a connection fails at the major US hubs
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.