Route reliability record

ATL→SFO

Atlanta to San Francisco

Flights: 3,354
Period: July 2025 to June 2026
Distance: 2,139 mi
Carriers: 3

This route sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 3,354 flights, of which United Airlines flew 637 at 78.1% on time.

The national on-time rate over the same period is 77.6%, so this route runs 6 points behind the country as a whole. Across a thousand flights that is about 62 extra late arrivals.

On time

71.4%

Arrivals under 15 minutes late, of 3,327 completed flights

Avg delay

58 min

Across delayed arrivals only, not all flights

Cancelled

0.63%

National rate is 1.81%

Best carrier

United

78.1% on time across 637 flights

These figures cover 3,354 flights between July 2025 and June 2026. Beyond the headline rate, 8.8% 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

Which airline is most reliable on ATL to SFO

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 Airlinesthin 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.

Departure window

The best time of day to leave

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 20 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am344 flights85.2%
8am–11am791 flights76.1%
11am–2pm224 flights73.7%
2pm–5pm452 flights70.0%
5pm–8pm1,026 flights65.0%
8pm–5am517 flights67.6%

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 85.2% of the time, against 65.0% for the evening window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 1,026 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 31 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

Darker means more delays. Figures are on-time percentages.March best, June worst

June is the worst month at 56.0% on time, 31 points below March, the best at 86.6%. 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. July was the busiest month here, with 319 flights.

Across the week, Tuesday is the strongest day at 78.6% on time and Sunday the weakest at 63.3%. 15 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

One category carries most of the weight here. National Airspace System accounts for 43% of the 56,000 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.

National Airspace System
43%
Carrier
38%
Late-arriving aircraft
15%
Extreme weather
4%

The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 21,000 of the 56,000 delay minutes reported here. The split is drawn from 55,617 reported delay minutes.

43% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 24,000 minutes out of 56,000, against a national NAS share of 21%.

Cancellations are rare at 0.63%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here actually costs

8.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the about an hour kind, which a normal layover absorbs.

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 81.6% on time across 3,350 flights, 10 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 10 points of difference.

The sample behind these figures is 3,354 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 86.6% on time and June 56.0%, a swing of 31 points. If the dates move at all, move them out of June before you think about anything else. 3,327 completed flights over 12 months sit behind that.

Common questions

ATL to SFO questions

How often is ATL to SFO delayed?

Roughly one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 28.6% of the 3,354 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on ATL to SFO?

United Airlines leads at 78.1% on time across 637 flights. Delta Air Lines is at the other end on 70.2%, a gap of 8 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on ATL to SFO?

The 5am–8am departure window is the strongest at 85.2% on time. The 5pm–8pm window is the weakest at 65.0%, 20 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are June delays on ATL to SFO?

June is the weakest month at 56.0% on time, compared with 86.6% in March. Across the year that is 31 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. ATL to SFO and SFO to ATL are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures