Carrier route record
F9ATL→SJU
Frontier Airlines · Atlanta to San Juan
- Flights
- 387
- Period
- September 2025 to August 2026
- Share of route
- 18%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Frontier Airlines.
Frontier on ATL to SJU earns a D, which is as low as this site's scale goes for a reason. Only 56.5% of flights arrive inside the 15-minute window, 21 points worse than the national rate of 77.3%. Late arrivals average about an hour. Treat any tight connection here as a coin flip. That rests on 387 flights, with a median arrival 10 minutes late.
The national on-time rate over the same period is 77.3%, so Frontier on ATL to SJU runs 21 points behind the country as a whole. Across a thousand flights that is about 208 extra late arrivals.
Key figures
On time
56.5%
Arrivals under 15 minutes late, of 377 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
1.81%
National rate is 1.89%
Whole route
71.6%
Every carrier on ATL to SJU, 2,101 flights
These figures cover 387 flights between September 2025 and August 2026. Beyond the headline rate, 14.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Frontier against every carrier on ATL to SJU
Frontier flew 387 of the 2,101 flights on ATL to SJU, about 18% of it. Its 56.5% on time is 15 points worse than the route as a whole, which runs 71.6%. Ranked by on-time rate it is number two 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 | 1,638 | 76.9% | 53 min | 0.85% | B+ |
| Frontier Airlines (this page) | 387 | 56.5% | 67 min | 1.81% | D |
| Spirit Airlinesthin sample | 76 | 30.0% | 62 min | 7.89% | F− |
Flight by flight
Frontier flight numbers on ATL to SJU
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 387 flights.
- 5am–8am11 flights—
- 8am–11am302 flights59.2%
- 11am–2pm16 flights—
- 2pm–5pm3 flights—
- 5pm–8pm16 flights—
- 8pm–5am39 flights50.0%
Scale runs 40% to 65%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 50.0% on time, against 59.2% for the 8am–11am 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 302 flights scheduled in it.
Across the year
Frontier on ATL to SJU through the year
December is the weak month at 46.3% on time, against 63.3% in July. 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. January was the busiest month here, with 43 flights.
Across the week, Wednesday is the strongest day at 75.6% on time and Saturday the weakest at 33.8%, a spread of 42 points.
Arrival by arrival
How late Frontier on ATL to SJU runs when it is late
The 164 late arrivals split 47 under half an hour, 63 between 30 and 60 minutes, and 54 an hour or more.
- 15+ min early27 flights7.2%
- Within 15 min186 flights49.3%
- 15–29 min late47 flights12.5%
- 30–59 min late63 flights16.7%
- 1–2 hours late31 flights8.2%
- 2+ hours late23 flights6.1%
Scale runs 0% to 100%.
Share of 377 completed flights by arrival against schedule.
40 of 193 late departures made up the time and arrived on time, 21% of them. 11 flights left on time and still arrived late.
The worst days
Worst days for Frontier on ATL to SJU
The latest arrival of the period was on 11 January 2026, 11 hours 27 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 11 January 2026 | 11 hours 27 minutes | Late-arriving aircraft |
| 4 January 2026 | 6 hours 37 minutes | Late-arriving aircraft |
| 29 May 2026 | 6 hours 21 minutes | Carrier |
| 16 March 2026 | 4 hours 17 minutes | Late-arriving aircraft |
| 4 August 2026 | 4 hours 8 minutes | National Airspace System |
Delay causes
Why Frontier runs late on this route
Late-arriving aircraft accounts for 51% of the 11,000 delay minutes carriers reported here, and the remaining four split what is left.
- 51%Late-arriving aircraft
- 28%Carrier
- 21%National Airspace System
- 0%Extreme weather
51% 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 51 to one. The split is drawn from 10,972 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 59.2% on time here.
Cancellations sit at 1.81% against a national 1.89%, which is ordinary. Diversions add another 0.78%.
Connections and stage length
What a delay here costs
14.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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 55.0% on time across 383 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. 387 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 ATL to SJU
Put together: treat all of this as provisional. 387 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 56.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 377 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to SJU, every carrier
- Frontier on SJU to ATL, the return leg
- Delta Air Lines on ATL to SJU76.9%
- Frontier Airlines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Luis Munoz Marin International (SJU) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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.