Route reliability record
ATL→STT
Atlanta to Charlotte Amalie
- Flights
- 719
- Period
- September 2025 to August 2026
- Distance
- 1,599 mi
- Carriers
- 1
This route lands a B+, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That rests on 719 ATL to STT flights, with a median arrival right on schedule.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
76.4%
Arrivals under 15 minutes late, of 712 completed flights
Avg delay
46 min
Across delayed arrivals only, not all flights
Cancelled
0.70%
National rate is 1.89%
Best carrier
Delta
76.4% on time across 719 flights
These figures cover 719 flights between September 2025 and August 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
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Carrier by carrier
Which airline is most reliable on ATL to STT
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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 719 | 76.4% | 46 min | 0.70% | B+ |
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Departure window
The best time of day to leave
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 719 flights.
- 5am–8am—
- 8am–11am459 flights79.3%
- 11am–2pm260 flights71.3%
- 2pm–5pm—
- 5pm–8pm—
- 8pm–5am—
Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 71.3% on time against 79.3% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8am–11am window is the busiest, with 459 flights scheduled in it.
Explore
Filter ATL to STT 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 ATL to STT, the best departure window is 8am–11am at 79.3% on time and the worst is 11am–2pm at 71.3%, a real gap of 8.0 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am—
- 8–11am79.3%
- 11am–2pm71.3%
- 2–5pm—
- 5–8pm—
- 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 28 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 63.0%. June is the strongest month at 90.5%. Moving a flexible trip across that boundary buys 28 points. March was the busiest month here, with 93 flights.
Across the week, Friday is the strongest day at 89.8% on time and Saturday the weakest at 61.4%, a spread of 28 points.
Delay causes
Why this route gets delayed
National Airspace System accounts for 48% of the 7,739 delay minutes carriers reported here, and the remaining four split what is left.
- 48%National Airspace System
- 41%Carrier
- 6%Late-arriving aircraft
- 4%Extreme weather
48% 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 3,724 minutes out of 7,739, against a national NAS share of 21%. The split is drawn from 7,739 reported delay minutes.
The largest share of delay minutes, 41%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 3,198 of the 7,739 delay minutes reported here.
Cancellations are rare at 0.70%, below the national 1.89% 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
Badly late arrivals are rare here: only 4.8% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
At 1,599 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 83.0% on time across 719 flights, 7 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 7 points of difference.
One caution: this is a thin sample. 719 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.
Work out the risk of missing a connection in STT after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 719 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 76.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 712 completed flights over 12 months sit behind that.
Common questions
ATL to STT questions
How often is ATL to STT delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 23.6% of the 719 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 45 minutes on average.
How reliable is ATL to STT compared with the rest of the country?
76.4% of flights arrive on time here against a national 77.3%, a difference of about a point against it. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on ATL to STT?
The 8am–11am departure window is the strongest at 79.3% on time. The 11am–2pm window is the weakest at 71.3%, 8 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 ATL to STT?
March is the weakest month at 63.0% on time, compared with 90.5% in June. Across the year that is 28 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
- STT to ATL — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- ATL to LGA, a related route72.3%
- MIA to STT, a related route78.2%
- ATL to MCO, a related route70.3%
- Delta Air Lines on-time record76.4%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. ATL to STT and STT to ATL 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.