ATL → SJU Flight Reliability

Right now

Origin · ATLNo disruption reported

Aviation weather is not currently a factor.

Updated 12:52 UTC

Atlanta airport profile →

Destination · SJUNo disruption reported

Aviation weather is not currently a factor.

Updated 12:56 UTC

San Juan airport profile →

Route reliability

July 2023 – July 2026

Route Reliability Score

62/ 100Good

Better than 41% of comparable major US routes (4,598 compared)

Calculated from 6,617 flights. How this is calculated

On-time arrivals

74.9%

4,908 of 6,551

Cancellation rate

0.82%

54 cancelled

Median arrival delay

-1 min

Average 11.4 min

Severe delays

7.8%

60+ minutes late

Delay when late

61 min

Average, when 15+ min late

Flights analyzed

6,617

3 carriers

ATL → SJU arrives on time 74.9% of the time; the return trip, SJU → ATL, arrives on time 81.3% of the time, a 6.4-point gap between the two directions of the same city pair.

ATL → SJU spends 23.7 minutes on the ground on a 1,547-mile trip: 18.0 minutes from pushback to wheels-up at ATL and 5.7 minutes from touchdown to gate at SJU.

Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026

What stands out

The airline matters unusually much on this route, a wider carrier-to-carrier gap than 97% of 2,692 comparable routes.

Delta Air Lines arrived on time 78.7% of the time, against 56.1% for Frontier Airlines, flying the exact same route.

Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 2,692 in the comparison.

What sets this route apart

Where ATL to SJU differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.

ATL to SJU struggles most at 10 AM: 64.7% of its flights scheduled then arrive on time, 15.5 points behind the 80.2% on routes of similar length at the same hour. Against all other routes the gap is 18.1 points.

ATL to SJU is at its best against routes of similar length for flights scheduled at 2 PM: 81.4% arrive on time, 8.4 points ahead of the 73.0% those routes manage at that hour. Against all other routes the gap is 6.8 points.

Saturday is the day ATL to SJU slips furthest against routes of similar length, 67.9% on time where they average 78.8%, 10.9 points lower. Against all other routes the gap is 11.2 points.

In March, ATL to SJU runs 7.8 points below routes of similar length, 70.7% on time to 78.5%. Against all other routes the gap is 7.2 points.

Frontier Airlines’ flights on ATL to SJU arrive on time 56.1% of the time, 13.5 points below the 69.6% it manages on its routes of similar length. Against all other routes the gap is 15.2 points.

ATL to SJU against comparable routes

July 2023 – July 2026

Where ATL to SJU differs most from comparable routes, with the group each figure is compared with and the flights behind it
Measure	This route	Compared with	Them	Gap	Flights behind it
Hour: 10 AM departures	64.7%	routes of similar length	80.2%	−15.5 pts	778 here, 88,673 there
Hour: 2 PM departures	81.4%	routes of similar length	73.0%	+8.4 pts	210 here, 86,128 there
Weekday: Saturday	67.9%	routes of similar length	78.8%	−10.9 pts	987 here, 208,203 there
Month: March	70.7%	routes of similar length	78.5%	−7.8 pts	649 here, 130,180 there
Airline: Frontier Airlines	56.1%	routes of similar length	69.6%	−13.5 pts	881 here, 64,588 there

Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 1,547 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.

Why ATL → SJU flights are cancelled

July 2023 – July 2026

ATL → SJU cancelled 54 of 6,617 scheduled flights — about 1 in every 123. The reason filed most often was the airline, 50.0% of the cancellations coded on this route — about 1 in every 245 scheduled flights.

Share of cancellations

Airline50.0%

Weather37.0%

Security11.1%

Air traffic1.9%

Of 54 cancelled departures carrying a reason code.

What each reason means

The airline1 in 245

Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.

27 cancellations, 50.0% of the total.

Extreme weather1 in 331

Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.

20 cancellations, 37.0% of the total.

Security1 in 1,103

A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.

6 cancellations, 11.1% of the total.

The air traffic system1 in 6,617

Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.

1 cancellation, 1.9% of the total.

Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.

54 coded cancellations were recorded on ATL → SJU; the section appears from 50.

When it goes wrong

July 2023 – July 2026

One arrival in ten is worse than

48 min late

against a median of 1 min early

Arrived an hour or more late7.8%

Typical delay when late61 min

Cancelled0.82%

Landed somewhere else0.18%

Percentiles over 6,617 operations; cancelled and diverted flights are counted separately.

Will your connection be tight enough?

Layovers at SJU after arriving from ATL.

Connection buffer and chance of missing by layover length, ATL → SJU arrivals
Connection time	Chance of missing	Reads as
30 min	47%	Likely to miss
45 min	24%	High risk
60 min	15%	High risk
90 min	7.7%	Some risk
120 min	4.6%	Low risk

This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.82% of the time and diverts 0.18% of the time, which a late arrival never shows up in.

Chance of missing is the share of 6,551 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.

The worst tenth of arrivals on this route land at least 48 minutes late (90th-percentile gate arrival delay), over 6,617 operations.

Any other layover length: connection checker.

Best time to fly

ATL → SJU flights departing 5–9 AM arrived on time 87.4% of the time, against 60.1% for 3–6 PM departures, a gap of 27.3 percentage points.

By departure window

5–9 AM87.4%

9 AM–12 PM74.2%

12–3 PM81.6%

3–6 PM60.1%

6–9 PM66.6%

9 PM–5 AM—

By departure hour

12 AM

3 AM

6 AM

9 AM

12 PM

3 PM

6 PM

9 PM

Departure windows with fewer than 120 flights are not scored.

Why ATL → SJU runs late

July 2023 – July 2026

The airline47.9%

crew, maintenance, boarding and fueling, all within the carrier’s control

Late-arriving aircraft25.4%

the inbound aircraft was late, so this flight started late

Air traffic control23.0%

airspace and airport capacity, including weather-driven flow control

Weather3.6%

weather severe enough to stop this flight specifically

Security0.1%

screening or terminal security incidents

Share of the delay minutes US DOT attributed to each cause for ATL → SJU. Only delays of 15 minutes or more are attributed.

Airlines on this route

Carriers with at least 200 flights, by the airline that operated each one.

Airlines on this route
Carrier	Flights	On time	Cancelled	Median delay	Severe
Delta Air Lines	5,001	78.7%	0.54%	-2 min	5.9%
Frontier Airlines	906	56.1%	2.21%	9 min	17.6%
Spirit Airlines	710	71.5%	0.99%	-2 min	9.1%

Delta Air Lines flew 75.6% of the 6,617 flights listed. Frontier Airlines cancelled 2.21% of its flights here against 0.54% for Delta Air Lines.

Delta Air Lines arrived on time 22.6 percentage points more often than Frontier Airlines on this route.

Flights on this route

Flight numbers with at least 600 operations here and still on the schedule.

Flights on this route
Flight	Scheduled	Operations	On time
DL1861 Delta Air Lines	6:55 PM	1,066	69.3%
DL1882 Delta Air Lines	9:55 AM	1,066	78.4%
DL1946 Delta Air Lines	1:00 PM	1,064	82.8%
F92082 Frontier Airlines	10:25 AM	617	56.5%

DL1946 (1:00 PM) arrived on time 82.8% of the time, 26.3 points more often than F92082 (10:25 AM) at 56.5%.

Weekly and seasonal patterns

By day of week

Mon72.7%

Tue79.5%

Wed82.2%

Thu76.9%

Fri76.2%

Sat67.9%

Sun70.5%

Wednesday is historically the most reliable day and Saturday the least, a gap of 14.3 percentage points.

By month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

July is historically the weakest month and October the strongest, a spread of 16.0 percentage points.

Reliability over time

July 2023 – July 2026

24

25

26

Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 70.9% against 74.3% in the 12 months before — declining by 3.4 percentage points.

Data and methodology

Calculated by FlyerIntel from 6,617 ATL → SJU flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.

Full methodology · Data sources · Report a problem

Analysis last recomputed September 26, 2026

ATL airport SJU airport Return direction SJU → ATL

ATL→SJU

Right now

Route reliability

What stands out

What sets this route apart

ATL to SJU against comparable routes

Why ATL → SJU flights are cancelled

Share of cancellations

What each reason means

When it goes wrong

Will your connection be tight enough?

Best time to fly

By departure window

By departure hour

Why ATL → SJU runs late

Airlines on this route

Flights on this route

Weekly and seasonal patterns

By day of week

By month

Reliability over time

Data and methodology