Carrier route record

F9PHL→SJU

Frontier Airlines · Philadelphia to San Juan

Flights: 915
Period: September 2025 to August 2026
Share of route: 46%
Carriers: 4

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

Frontier on PHL to SJU earns a D−, which is as low as this site's scale goes for a reason. Only 55.6% of flights arrive inside the 15-minute window, 22 points worse than the national rate of 77.3%. Late arrivals average a little over an hour. Treat any tight connection here as a coin flip. That rests on 915 flights, with a median arrival 8 minutes late.

The national on-time rate over the same period is 77.3%, so Frontier on PHL to SJU runs 22 points behind the country as a whole. Across a thousand flights that is about 217 extra late arrivals.

On time

55.6%

Arrivals under 15 minutes late, of 883 completed flights

Avg delay

77 min

Across delayed arrivals only, not all flights

Cancelled

3.17%

National rate is 1.89%

Whole route

63.3%

Every carrier on PHL to SJU, 1,992 flights

These figures cover 915 flights between September 2025 and August 2026. Beyond the headline rate, 17.7% 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 PHL to SJU

Frontier flew 915 of the 1,992 flights on PHL to SJU, about 46% of it. Its 55.6% on time is 8 points worse than the route as a whole, which runs 63.3%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from American at 71.4% to Frontier at 55.6%. Two 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 PHL to SJU
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlines	763	71.4%	77 min	1.97%	C
JetBlue Airwaysthin sample	159	70.2%	94 min	4.40%	C−
Spirit Airlinesthin sample	155	61.9%	67 min	10.32%	D−
Frontier Airlines (this page)	915	55.6%	77 min	3.17%	D−

Flight by flight

Frontier flight numbers on PHL 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 matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against half a point between the best and worst carrier.

5am–8am157 flights65.1%
8am–11am80 flights53.8%
11am–2pm164 flights56.0%
2pm–5pm85 flights47.6%
5pm–8pm96 flights42.9%
8pm–5am333 flights57.0%

Scale runs 35% to 70%.

The 5pm–8pm window is where this operation falls apart: 42.9% on time, against 65.1% for the 5am–8am 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 8pm–5am window is the busiest, with 333 flights scheduled in it.

Across the year

Frontier on PHL to SJU through the year

Darker means more delays. Figures are on-time percentages.May best, July worst

July is the worst month at 37.2% on time, 35 points below May, the best at 72.6%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. August was the busiest month here, with 93 flights.

Across the week, Wednesday is the strongest day at 63.8% on time and Saturday the weakest at 48.1%, a spread of 16 points.

Arrival by arrival

How late Frontier on PHL to SJU runs when it is late

The 392 late arrivals split 113 under half an hour, 123 between 30 and 60 minutes, and 156 an hour or more.

15+ min early173 flights19.6%
Within 15 min318 flights36.0%
15–29 min late113 flights12.8%
30–59 min late123 flights13.9%
1–2 hours late100 flights11.3%
2+ hours late56 flights6.3%

Scale runs 0% to 100%.

Share of 883 completed flights by arrival against schedule.

Time lost at the gate mostly stays lost. Of 315 departures that left 15 minutes late or more, only 26 made it up before arrival. In the other direction, 103 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SJU.

The worst days

Worst days for Frontier on PHL to SJU

The latest arrival of the period was on 14 June 2026, 19 hours 46 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The five worst days are spread across June, August, April and May, with no single month standing out.

The latest arrivals of Frontier on PHL to SJU in the period
Date	Arrived late by	Largest filed cause
14 June 2026	19 hours 46 minutes	Carrier
15 August 2026	16 hours 48 minutes	Extreme weather
22 June 2026	11 hours 53 minutes	Extreme weather
9 April 2026	9 hours 51 minutes	Late-arriving aircraft
1 May 2026	9 hours 5 minutes	Carrier

Delay causes

Why Frontier runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 30,000 reported delay minutes.

Carrier
37%
Late-arriving aircraft
33%
National Airspace System
22%
Extreme weather
9%

The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 11,000 of the 30,000 delay minutes reported here. The split is drawn from 30,254 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 65.1% on time here.

Cancellations run at 3.17%, against 1.89% nationally. That is about one flight in 30 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and stage length

What a delay here costs

17.7% 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 1,576 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 63.3% on time across 916 flights, 8 points above 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 8 points of difference.

One caution: this is a thin sample. 915 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 PHL to SJU

Put together: the delay figures matter less here than the 3.17% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 883 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