Route reliability record

SFO→ATL

San Francisco to Atlanta

Flights: 3,350
Period: July 2025 to June 2026
Distance: 2,139 mi
Carriers: 3

This route lands a B+, 4 points better than the national rate of 77.6%. Roughly one flight in five arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 3,350 flights, of which United Airlines flew 637 at 86.5% on time.

Set against the rest of the country, this route's record is 4 points better than the US average of 77.6%. That gap is worth roughly 40 fewer late arrivals for every thousand flights.

On time

81.6%

Arrivals under 15 minutes late, of 3,315 completed flights

Avg delay

67 min

Across delayed arrivals only, not all flights

Cancelled

0.81%

National rate is 1.81%

Best carrier

United

86.5% on time across 637 flights

These figures cover 3,350 flights between July 2025 and June 2026. The median arrival is 7 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Which airline is most reliable on SFO to ATL

The two carriers here are closely matched: 4 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.

On-time performance by carrier on SFO to ATL
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	637	86.5%	54 min	0.16%	A+
Delta Air Lines	2,407	83.0%	68 min	0.66%	B+
Frontier Airlinesthin sample	306	59.7%	72 min	3.27%	D−

No carrier stands out. United tops the table at 86.5%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.

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 19 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am539 flights92.3%
8am–11am628 flights88.7%
11am–2pm565 flights82.4%
2pm–5pm308 flights80.8%
5pm–8pm—
8pm–5am1,310 flights73.6%

Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 92.3% of the time, against 73.6% for the overnight window. That is 19 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 1,310 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 16 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.February best, May worst

Delays peak in May, when the on-time rate falls to 73.2%. February is the strongest month at 89.0%. Moving a flexible trip across that boundary buys 16 points. July was the busiest month here, with 319 flights.

Across the week, Tuesday is the strongest day at 84.5% on time and Friday the weakest at 78.0%. 7 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. Late-arriving aircraft accounts for 46% of the 41,000 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
46%
Carrier
42%
National Airspace System
11%
Extreme weather
1%

46% 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 41,000 reported delay minutes here, that single category outweighs weather by 32 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 40,863 reported delay minutes.

The largest share of delay minutes, 42%, 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 17,000 of the 41,000 delay minutes reported here.

Cancellations are rare at 0.81%, 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

6.0% 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 71.4% on time across 3,354 flights, 10 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 10 points of difference.

The sample behind these figures is 3,350 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. February runs 89.0% on time and May 73.2%, a swing of 16 points. If the dates move at all, move them out of May before you think about anything else. 3,315 completed flights over 12 months sit behind that.

Common questions

SFO to ATL questions

How often is SFO to ATL delayed?

Roughly one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.4% of the 3,350 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on SFO to ATL?

United Airlines leads at 86.5% on time across 637 flights. Delta Air Lines is at the other end on 83.0%, a gap of 4 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 SFO to ATL?

The 5am–8am departure window is the strongest at 92.3% on time. The 8pm–5am window is the weakest at 73.6%, 19 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 May delays on SFO to ATL?

May is the weakest month at 73.2% on time, compared with 89.0% in February. Across the year that is 16 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. SFO to ATL and ATL to SFO 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