Flight number record
DL 1329
Delta Air Lines · Atlanta to Philadelphia
- Route
- ATL → PHL
- Departs
- 16:25
- Flights
- 276
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1329, check with Delta Air Lines.
DL 1329 draws a D−. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is roughly 55 minutes behind schedule. Build slack into anything you connect to. That rests on 276 flights, with a median arrival 8 minutes late.
The national on-time rate over the same period is 77.6%, so DL 1329 runs 17 points behind the country as a whole. Across a thousand flights that is about 172 extra late arrivals.
Key figures
On time
60.4%
Arrivals under 15 minutes late, of 265 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
3.99%
National rate is 1.81%
1 hour+ late
9.8%
National rate is 8.1%
These figures cover 276 flights between July 2025 and June 2026. Beyond the headline rate, 9.8% 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 1329 flies
DL 1329 flies ATL to PHL without a single fixed slot. Its most common scheduled departure was 16:25, used on 44 of 276 flights, with 16:23 (36 flights) and 15:50 (33 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 16:2544 flights15.9%
- Departs 16:2336 flights13.0%
- Departs 15:5033 flights12.0%
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 16:25 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and DL 1329 runs 12 points worse at 60.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Against the route
DL 1329 next to ATL to PHL
Every carrier on ATL to PHL combined arrived on time 74.9% of the time across 5,713 flights, so DL 1329 is 15 points behind it. Delta flew 3,028 flights on the same city pair under all its flight numbers, including this one, and those ran 76.1% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 21 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1329thin sample | 276 | 60.4% | 53 min | 3.99% | D− |
| All Delta Air Lines on ATL–PHL | 3,028 | 76.1% | 52 min | 2.48% | B |
| All carriers on ATL–PHL | 5,713 | 74.9% | 72 min | 2.84% | C |
| Delta Air Lines, whole network | 1,038,570 | 81.6% | 71 min | 1.62% | B |
Across the year
DL 1329 quarter by quarter
DL 1329 did not run the same all year. Its best quarter was Oct–Dec 2025 at 75.3% on time and its weakest Apr–Jun 2026 at 48.4%, a swing of 27 points on roughly 69 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 202549 flights51.0%
- Oct–Dec 202580 flights75.3%
- Jan–Mar 202682 flights61.0%
- Apr–Jun 202665 flights48.4%
Scale runs 40% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, DL 1329 did best on Saturday at 82.9% on time and worst on Thursday at 41.5%. Each day rests on about 39 flights, so a gap of 41 points is worth noticing but could still narrow in another year.
Delay causes
Why DL 1329 runs late
One category carries most of the weight here. National Airspace System accounts for 43% of the 5,561 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.
- 43%National Airspace System
- 40%Carrier
- 18%Late-arriving aircraft
- 0%Extreme weather
43% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,364 minutes out of 5,561, against a national NAS share of 21%. The split is drawn from 5,561 delay minutes reported on DL 1329.
Cancellations run at 3.99%, against 1.81% nationally. That is about one flight in 25 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
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. 9.8% 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 666 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 PHL to ATL (187) and DFW to LGA (3), but none flew often enough under DL 1329 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ATL to PHL only.
One caution: this is a thin sample. 276 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 1329
For a booking, the cancellation rate is the figure to plan around on DL 1329: 3.99% of its 276 scheduled flights did not operate. A late arrival costs roughly 55 minutes, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- ATL to PHL, every carrier and departure
- PHL to ATL, the return direction
- Delta Air Lines 2642 on the same route76.9%
- Delta Air Lines 2270 on the same route86.2%
- Delta Air Lines 1169 on the same route71.3%
- Delta Air Lines 2065 on the same route63.4%
- Frontier Airlines 3210 on the same route75.6%
- Frontier Airlines 2298 on the same route64.6%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Philadelphia International (PHL) 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.