Carrier route record

DLSJU→ATL

Delta Air Lines · San Juan to Atlanta

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 SJU to ATL earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 14 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 1,638 flights, with a median arrival 12 minutes early.

Set against the rest of the country, Delta's SJU to ATL record is 14 points better than the US average of 77.3%. That gap is worth roughly 136 fewer late arrivals for every thousand flights.

On time

90.9%

Arrivals under 15 minutes late, of 1,613 completed flights

Avg delay

78 min

Across delayed arrivals only, not all flights

Cancelled

0.85%

National rate is 1.89%

Whole route

81.6%

Every carrier on SJU to ATL, 2,097 flights

These figures cover 1,638 flights between September 2025 and August 2026. The median arrival is 12 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

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Carrier by carrier

Delta against every carrier on SJU to ATL

Delta flew 1,638 of the 2,097 flights on SJU to ATL, most of the route. Its 90.9% on time is 9 points better than the route as a whole, which runs 81.6%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 90.9% to Spirit at 8.6%. 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.

On-time performance by carrier on SJU to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	1,638	90.9%	78 min	0.85%	A+
Frontier Airlines	383	55.0%	87 min	2.09%	D
Spirit Airlinesthin sample	76	8.6%	66 min	7.89%	F−

Flight by flight

Delta flight numbers on SJU to ATL

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Departure window

When Delta runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 1,638 flights.

5am–8am548 flights95.4%
8am–11am—
11am–2pm241 flights89.8%
2pm–5pm484 flights88.4%
5pm–8pm365 flights88.1%
8pm–5am—

Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.

The early departures do better, though not dramatically: 95.4% on time for the 5am–8am window against 88.1% for 5pm–8pm. Worth taking if the schedule allows, not worth an extra connection. The 5am–8am window is the busiest, with 548 flights scheduled in it.

Across the year

Delta on SJU to ATL through the year

Darker means more delays. Figures are on-time percentages.December best, January worst

January is the weak month at 85.3% on time, against 94.4% in December. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. March was the busiest month here, with 159 flights.

Across the week, Wednesday is the strongest day at 94.9% on time and Sunday the weakest at 85.7%, a spread of 9 points.

Arrival by arrival

How late Delta on SJU to ATL runs when it is late

Delta on SJU to ATL often beats the schedule: 655 of 1,613 completed flights, 41%, arrived 15 minutes or more early. The 147 late arrivals split 55 under half an hour, 49 between 30 and 60 minutes, and 43 an hour or more.

15+ min early655 flights40.6%
Within 15 min811 flights50.3%
15–29 min late55 flights3.4%
30–59 min late49 flights3.0%
1–2 hours late27 flights1.7%
2+ hours late16 flights1.0%

Scale runs 0% to 100%.

Share of 1,613 completed flights by arrival against schedule.

A late pushback is often recovered here: of 176 departures that left 15 minutes late or more, 59 still arrived on time. Only 30 left on time and still arrived late.

The worst days

Worst days for Delta on SJU to ATL

The latest arrival of the period was on 25 September 2025, 17 hours 51 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on five of the five worst days.

The latest arrivals of Delta on SJU to ATL in the period
Date	Arrived late by	Largest filed cause
25 September 2025	17 hours 51 minutes	Carrier
15 November 2025	15 hours 32 minutes	Carrier
30 October 2025	10 hours 9 minutes	Carrier
2 January 2026	9 hours 28 minutes	Carrier
11 November 2025	9 hours 5 minutes	Carrier

Delay causes

Why Delta runs late on this route

Carrier accounts for 50% of the 11,000 delay minutes carriers reported here, and the remaining four split what is left.

Carrier
50%
Late-arriving aircraft
40%
National Airspace System
10%
Extreme weather
1%

40% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 11,000 reported delay minutes here, that single category outweighs weather by 40 to one. The split is drawn from 11,424 reported delay minutes.

The largest share of delay minutes, 50%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 5,673 of the 11,000 delay minutes reported here.

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

Badly late arrivals are rare here: only 2.7% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

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 76.9% on time across 1,638 flights, 14 points below 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 SJU to ATL

Put together: take the 5am–8am departure, avoid January if the dates are flexible, and if two carriers are within a few dollars of each other, Frontier is the one with the record behind it. None of that guarantees an on-time arrival; it moves the odds by 7 points, which is the most any booking decision can do. 1,613 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures