Carrier route record

F9SJU→ATL

Frontier Airlines · San Juan to Atlanta

Flights: 365
Period: July 2025 to June 2026
Share of route: 17%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.

Frontier on SJU to ATL earns a D, which is as low as this site's scale goes for a reason. Only 56.9% of flights arrive inside the 15-minute window, 21 points worse than the national rate of 77.6%. Late arrivals average an hour and a half. Treat any tight connection here as a coin flip. That rests on 365 flights, with a median arrival 8 minutes late.

The national on-time rate over the same period is 77.6%, so Frontier on SJU to ATL runs 21 points behind the country as a whole. Across a thousand flights that is about 207 extra late arrivals.

On time

56.9%

Arrivals under 15 minutes late, of 353 completed flights

Avg delay

92 min

Across delayed arrivals only, not all flights

Cancelled

2.19%

National rate is 1.81%

Whole route

82.0%

Every carrier on SJU to ATL, 2,126 flights

These figures cover 365 flights between July 2025 and June 2026. Beyond the headline rate, 17.6% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Frontier against every carrier on SJU to ATL

Frontier flew 365 of the 2,126 flights on SJU to ATL, about 17% of it. Its 56.9% on time is 25 points worse than the route as a whole, which runs 82.0%. Ranked by on-time rate it is number two 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	1,637	90.8%	81 min	0.92%	A+
Frontier Airlines (this page)	365	56.9%	92 min	2.19%	D
Spirit Airlinesthin sample	124	37.3%	62 min	4.84%	F−

Flight by flight

Frontier flight numbers on SJU to ATL

F9 287117:1557.2% · 293 flights

Departure window

When Frontier 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 365 flights.

5am–8am55 flights51.9%
8am–11am4 flights—
11am–2pm19 flights—
2pm–5pm222 flights57.0%
5pm–8pm61 flights54.1%
8pm–5am4 flights—

Scale runs 45% to 60%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 2pm–5pm slot at 57.0% on time, ahead of 5am–8am at 51.9%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 2pm–5pm window is the busiest, with 222 flights scheduled in it.

Across the year

Frontier on SJU to ATL through the year

Jul–Sep 202565 flights50.8%
Oct–Dec 202595 flights59.1%
Jan–Mar 2026110 flights55.8%
Apr–Jun 202695 flights60.0%

Scale runs 40% to 65%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 56.9% on time across 365 flights.

Quarter by quarter Frontier on SJU to ATL held fairly steady: 50.8% in Jul–Sep 2025, 59.1% in Oct–Dec 2025, 55.8% in Jan–Mar 2026 and 60.0% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Across the week, Wednesday is the strongest day at 77.4% on time and Sunday the weakest at 44.8%. 33 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 52% of the 14,000 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.

Late-arriving aircraft
52%
Carrier
31%
National Airspace System
16%
Extreme weather
1%

52% 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 14,000 reported delay minutes here, that single category outweighs weather by 52 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 13,923 reported delay minutes.

Cancellations sit at 2.19% against a national 1.81%, which is ordinary. Diversions add another 1.10%.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 17.6% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

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 runs 54.7% on time across 369 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 365 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Frontier on SJU to ATL

Put together: treat all of this as provisional. 365 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 56.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 353 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