Carrier route record

DLSJU→ATL

Delta Air Lines · San Juan to Atlanta

Flights: 1,637
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 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 13 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 1,637 flights, with a median arrival 12 minutes early.

Set against the rest of the country, Delta's SJU to ATL record is 13 points better than the US average of 77.6%. That gap is worth roughly 132 fewer late arrivals for every thousand flights.

On time

90.8%

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

Avg delay

81 min

Across delayed arrivals only, not all flights

Cancelled

0.92%

National rate is 1.81%

Whole route

82.0%

Every carrier on SJU to ATL, 2,126 flights

These figures cover 1,637 flights between July 2025 and June 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.

Carrier by carrier

Delta against every carrier on SJU to ATL

Delta flew 1,637 of the 2,126 flights on SJU to ATL, most of the route. Its 90.8% on time is 9 points better than the route as a whole, which runs 82.0%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 90.8% to Spirit at 37.3%. 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)	1,637	90.8%	81 min	0.92%	A+
Frontier Airlines	365	56.9%	92 min	2.19%	D
Spirit Airlinesthin sample	124	37.3%	62 min	4.84%	F−

Flight by flight

Delta flight numbers on SJU to ATL

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 1,637 flights.

5am–8am559 flights95.1%
8am–11am—
11am–2pm229 flights89.7%
2pm–5pm484 flights88.2%
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: 95.1% 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 559 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 94.0% on time and Monday the weakest at 86.5%. 8 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 49% of the 12,000 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.

Carrier
49%
Late-arriving aircraft
41%
National Airspace System
10%
Extreme weather
1%

41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 12,000 reported delay minutes here, that single category outweighs weather by 41 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 12,060 reported delay minutes.

The largest share of delay minutes, 49%, 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 5,909 of the 12,000 delay minutes reported here.

Cancellations sit at 0.92% against a national 1.81%, which is ordinary. Diversions add another 0.55%.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 2.9% land an hour or more behind schedule, against 8.1% 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 75.8% on time across 1,636 flights, 15 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 15 points of difference.

The sample behind these figures is 1,637 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures