Carrier route record
DLATL→SJU
Delta Air Lines · Atlanta to San Juan
- Flights
- 1,636
- Period
- July 2025 to June 2026
- Share of route
- 77%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on ATL to SJU sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land about 50 minutes behind schedule. That rests on 1,636 flights, with a median arrival right on schedule.
The US average over the same twelve months is 77.6%, so there is little to separate Delta on ATL to SJU from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.8%
Arrivals under 15 minutes late, of 1,620 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
0.92%
National rate is 1.81%
Whole route
70.5%
Every carrier on ATL to SJU, 2,130 flights
These figures cover 1,636 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Delta against every carrier on ATL to SJU
Delta flew 1,636 of the 2,130 flights on ATL to SJU, most of the route. Its 75.8% on time is 5 points better than the route as a whole, which runs 70.5%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 75.8% to Spirit at 46.2%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 1,636 | 75.8% | 51 min | 0.92% | B+ |
| Frontier Airlines | 369 | 54.7% | 75 min | 1.63% | F |
| Spirit Airlinesthin sample | 125 | 46.2% | 56 min | 4.80% | F− |
Flight by flight
Delta flight numbers on ATL to SJU
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 30 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am32 flights90.3%
- 8am–11am681 flights80.9%
- 11am–2pm365 flights81.8%
- 2pm–5pm74 flights69.9%
- 5pm–8pm448 flights64.3%
- 8pm–5am36 flights60.0%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 60.0% on time, against 90.3% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 681 flights scheduled in it.
Across the year
Delta on ATL to SJU through the year
July is the worst month at 68.2% on time, 17 points below June, the best at 85.1%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. March was the busiest month here, with 159 flights.
Across the week, Wednesday is the strongest day at 84.5% on time and Sunday the weakest at 67.6%. 17 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. Carrier accounts for 57% of the 20,000 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.
- 57%Carrier
- 23%National Airspace System
- 16%Late-arriving aircraft
- 3%Extreme weather
- 0%Security
The largest share of delay minutes, 57%, 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 11,000 of the 20,000 delay minutes reported here. The split is drawn from 19,984 reported delay minutes.
Cancellations sit at 0.92% against a national 1.81%, which is ordinary. Diversions add another 0.06%.
Connections and stage length
What a delay here costs
5.9% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 50 minutes, which a normal layover absorbs.
At 1,547 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.
The return leg is a different operation and performs like one: it runs 90.8% on time across 1,637 flights, 15 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 15 points of difference.
The sample behind these figures is 1,636 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking Delta on ATL to SJU
Put together: the calendar is the biggest lever here, not the carrier or the hour. June runs 85.1% on time and July 68.2%, a swing of 17 points. If the dates move at all, move them out of July before you think about anything else. 1,620 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to SJU, every carrier
- Delta on SJU to ATL, the return leg
- Frontier Airlines on ATL to SJU54.7%
- Spirit Airlines on ATL to SJU46.2%
- Delta Air Lines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Luis Munoz Marin International (SJU) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
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.