Carrier route record
DLATL→SJU
Delta Air Lines · Atlanta to San Juan
- Flights
- 1,638
- Period
- September 2025 to August 2026
- Share of route
- 78%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on ATL to SJU lands a B+, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That rests on 1,638 flights, with a median arrival 1 minute early.
The US average over the same twelve months is 77.3%, 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
76.9%
Arrivals under 15 minutes late, of 1,624 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
0.85%
National rate is 1.89%
Whole route
71.6%
Every carrier on ATL to SJU, 2,101 flights
These figures cover 1,638 flights between September 2025 and August 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.
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Carrier by carrier
Delta against every carrier on ATL to SJU
Delta flew 1,638 of the 2,101 flights on ATL to SJU, most of the route. Its 76.9% on time is 5 points better than the route as a whole, which runs 71.6%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 76.9% to Spirit at 30.0%. 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) | 1,638 | 76.9% | 53 min | 0.85% | B+ |
| Frontier Airlines | 387 | 56.5% | 67 min | 1.81% | D |
| Spirit Airlinesthin sample | 76 | 30.0% | 62 min | 7.89% | F− |
Flight by flight
Delta flight numbers on ATL to SJU
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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.
- 5am–8am32 flights90.3%
- 8am–11am693 flights82.6%
- 11am–2pm365 flights81.8%
- 2pm–5pm68 flights74.6%
- 5pm–8pm444 flights64.8%
- 8pm–5am36 flights60.0%
Scale runs 50% to 95%.
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 693 flights scheduled in it.
Across the year
Delta on ATL to SJU through the year
Delays peak in April, when the on-time rate falls to 69.2%. June is the strongest month at 85.1%. Moving a flexible trip across that boundary buys 16 points. March was the busiest month here, with 159 flights.
Across the week, Wednesday is the strongest day at 84.9% on time and Sunday the weakest at 65.7%, a spread of 19 points.
Arrival by arrival
How late Delta on ATL to SJU runs when it is late
The 375 late arrivals split 163 under half an hour, 111 between 30 and 60 minutes, and 101 an hour or more.
- 15+ min early155 flights9.5%
- Within 15 min1,094 flights67.4%
- 15–29 min late163 flights10.0%
- 30–59 min late111 flights6.8%
- 1–2 hours late71 flights4.4%
- 2+ hours late30 flights1.8%
Scale runs 0% to 100%.
Share of 1,624 completed flights by arrival against schedule.
43 of 316 late departures made up the time and arrived on time, 14% of them. In the other direction, 102 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SJU.
The worst days
Worst days for Delta on ATL to SJU
The latest arrival of the period was on 6 March 2026, 12 hours 30 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in March 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 6 March 2026 | 12 hours 30 minutes | Carrier |
| 6 March 2026 | 6 hours 16 minutes | Carrier |
| 16 March 2026 | 5 hours | National Airspace System |
| 25 May 2026 | 3 hours 42 minutes | Carrier |
| 17 July 2026 | 3 hours 42 minutes | Carrier |
Delay causes
Why Delta runs late on this route
Carrier accounts for 58% of the 20,000 delay minutes carriers reported here, and the remaining four split what is left.
- 58%Carrier
- 22%National Airspace System
- 17%Late-arriving aircraft
- 2%Extreme weather
- 0%Security
The largest share of delay minutes, 58%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 12,000 of the 20,000 delay minutes reported here. The split is drawn from 19,809 reported delay minutes.
Cancellations are rare at 0.85%, below the national 1.89% 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 stage length
What a delay here costs
6.2% 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 roughly 55 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 90.9% on time across 1,638 flights, 14 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 14 points of difference.
The sample behind these figures is 1,638 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 April 69.2%, a swing of 16 points. If the dates move at all, move them out of April before you think about anything else. 1,624 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 SJU56.5%
- 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 7.05 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.