Carrier route record

F9ATL→SFO

Frontier Airlines · Atlanta to San Francisco

Flights: 307
Period: July 2025 to June 2026
Share of route: 9%
Carriers: 3

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

Frontier on ATL to SFO draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 307 flights. The strongest carrier on the route with a full sample, United Airlines, flew 637 at 78.1% on time.

The national on-time rate over the same period is 77.6%, so Frontier on ATL to SFO runs 11 points behind the country as a whole. Across a thousand flights that is about 110 extra late arrivals.

On time

66.6%

Arrivals under 15 minutes late, of 302 completed flights

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

1.30%

National rate is 1.81%

Whole route

71.4%

Every carrier on ATL to SFO, 3,354 flights

These figures cover 307 flights between July 2025 and June 2026. Beyond the headline rate, 12.6% 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 ATL to SFO

Frontier flew 307 of the 3,354 flights on ATL to SFO, about 9% of it. Its 66.6% on time is 5 points worse than the route as a whole, which runs 71.4%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from United at 78.1% to Frontier at 66.6%.

The choice of carrier is not cosmetic here. United Airlines arrives on time 78.1% of the time; Delta Air Lines manages 70.2%. Sample sizes sit next to every figure, because a two-point gap across 2,410 flights means less than a ten-point one.

On-time performance by carrier on ATL to SFO
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	637	78.1%	65 min	0.31%	B+
Delta Air Lines	2,410	70.2%	55 min	0.62%	C+
Frontier Airlines (this page)thin sample	307	66.6%	71 min	1.30%	C

United leads Delta by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

Frontier flight numbers on ATL to SFO

F9 194918:5568.6% · 261 flights

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 24 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am39 flights73.7%
11am–2pm—
2pm–5pm72 flights82.9%
5pm–8pm196 flights59.3%
8pm–5am—

Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 59.3% on time, against 82.9% for the 2pm–5pm 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 5pm–8pm window is the busiest, with 196 flights scheduled in it.

Across the year

Frontier on ATL to SFO through the year

Jul–Sep 202579 flights59.5%
Oct–Dec 202570 flights64.3%
Jan–Mar 202667 flights76.6%
Apr–Jun 202691 flights67.4%

Scale runs 50% to 80%. 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 66.6% on time across 307 flights.

Frontier on ATL to SFO did not run the same all year. Its best quarter was Jan–Mar 2026 at 76.6% on time and its weakest Jul–Sep 2025 at 59.5%, a swing of 17 points on roughly 77 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Wednesday is the strongest day at 77.4% on time and Sunday the weakest at 53.2%. 24 points is a smaller lever than departure hour, but it is free.

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 7,157 reported delay minutes.

Late-arriving aircraft
38%
Carrier
33%
National Airspace System
28%
Extreme weather
1%

38% 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 7,157 reported delay minutes here, that single category outweighs weather by 28 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 7,157 reported delay minutes.

Cancellations sit at 1.30% against a national 1.81%, which is ordinary. Diversions add another 0.33%.

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. 12.6% 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 2,139 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 59.7% on time across 306 flights, 7 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 7 points of difference.

One caution: this is a thin sample. 307 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 SFO

Put together: treat all of this as provisional. 307 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 66.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 302 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