Route reliability record
SJU→ATL
San Juan to Atlanta
- Flights
- 2,097
- Period
- September 2025 to August 2026
- Distance
- 1,547 mi
- Carriers
- 3
This route lands a B, 4 points better than the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 2,097 SJU to ATL flights, of which Delta Air Lines flew 1,638 at 90.9% on time.
Best time to fly SJU to ATL: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 91.4% of the time and Wednesday flights 87.9%, against 81.6% for the route overall.
Set against the rest of the country, this route's record is 4 points better than the US average of 77.3%. That gap is worth roughly 43 fewer late arrivals for every thousand flights.
Key figures
On time
81.6%
Arrivals under 15 minutes late, of 2,056 completed flights
Avg delay
80 min
Across delayed arrivals only, not all flights
Cancelled
1.34%
National rate is 1.89%
Best carrier
Delta
90.9% on time across 1,638 flights
These figures cover 2,097 flights between September 2025 and August 2026. The median arrival is 10 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.
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Carrier by carrier
Which airline is most reliable on SJU to ATL
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 90.9% of the time; Frontier Airlines manages 55.0%. Sample sizes sit next to every figure, because a two-point gap across 383 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 1,638 | 90.9% | 78 min | 0.85% | A+ |
| Frontier Airlines | 383 | 55.0% | 87 min | 2.09% | D |
| Spirit Airlinesthin sample | 76 | 8.6% | 66 min | 7.89% | F− |
The spread between Delta and Frontier is 36 points, wide enough that it should decide the booking. On a hundred trips that is 36 more arrivals inside the on-time window.
Flight by flight
Flights on SJU to ATL
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly San Juan to Atlanta
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SJU → ATLSan Juan to Atlanta | Delta Air Lines | 90.1% | 90.9% | 0.85% | 5am–8am, Wed | DL 1763 07:30 |
| 2. SJU → ATLSan Juan to Atlanta | Frontier Airlines | 53.9% | 55.0% | 2.09% | 2pm–5pm, Wed | F9 2871 17:15 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 16 points, against 36 points between the best and worst carrier.
- 5am–8am603 flights91.4%
- 8am–11am6 flights—
- 11am–2pm302 flights78.0%
- 2pm–5pm681 flights79.4%
- 5pm–8pm501 flights75.0%
- 8pm–5am4 flights—
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.4% of the time, against 75.0% for the evening window. That is 16 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 681 flights scheduled in it.
Explore
Filter SJU to ATL by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SJU to ATL, the best departure window is 5am–8am at 91.4% on time and the worst is 5pm–8pm at 75.0%, a wide gap of 16.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am91.4%
- 8–11am—
- 11am–2pm78.0%
- 2–5pm79.4%
- 5–8pm75.0%
- 8pm–5am—
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 14 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.
Delays peak in March, when the on-time rate falls to 73.6%. June is the strongest month at 87.9%. Moving a flexible trip across that boundary buys 14 points. March was the busiest month here, with 229 flights.
Across the week, Wednesday is the strongest day at 87.9% on time and Sunday the weakest at 76.3%, a spread of 12 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 43% of the 30,000 delay minutes carriers reported here, and the remaining four split what is left.
- 43%Late-arriving aircraft
- 36%Carrier
- 21%National Airspace System
- 0%Extreme weather
- 0%Security
43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 30,000 reported delay minutes here, that single category outweighs weather by 43 to one. The split is drawn from 30,244 reported delay minutes.
The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 11,000 of the 30,000 delay minutes reported here.
Cancellations sit at 1.34% against a national 1.89%, which is ordinary. Diversions add another 0.62%.
Connections and stage length
What a delay here actually costs
6.4% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
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 is a different operation and performs like one: it runs 71.6% on time across 2,101 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 2,097 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.
Work out the risk of missing a connection in ATL after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. June runs 87.9% on time and March 73.6%, a swing of 14 points. If the dates move at all, move them out of March before you think about anything else. 2,056 completed flights over 12 months sit behind that.
Common questions
SJU to ATL questions
How often is SJU to ATL delayed?
Roughly one flight in five arrives 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 2,097 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on SJU to ATL?
Delta Air Lines leads at 90.9% on time across 1,638 flights. Frontier Airlines is at the other end on 55.0%, a gap of 36 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 SJU to ATL?
The 5am–8am departure window is the strongest at 91.4% on time. The 5pm–8pm window is the weakest at 75.0%, 16 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 March delays on SJU to ATL?
March is the weakest month at 73.6% on time, compared with 87.9% in June. Across the year that is 14 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- ATL to SJU — the return legseparate record
- Luis Munoz Marin International (SJU) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Delta Air Lines on SJU to ATL90.9%
- Frontier Airlines on SJU to ATL55.0%
- SJU to MCO, a related route78.0%
- LGA to ATL, a related route75.5%
- SJU to JFK, a related route77.8%
- Delta Air Lines on-time record90.9%
- Frontier Airlines on-time record55.0%
- Spirit Airlines on-time record8.6%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. SJU to ATL and ATL to SJU are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.