Route reliability record
STL→ATL
St. Louis to Atlanta
- Flights
- 3,673
- Period
- September 2025 to August 2026
- Distance
- 484 mi
- Carriers
- 3
This route earns a B. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 3,673 STL to ATL flights, of which Delta Air Lines flew 2,348 at 89.5% on time.
Best time to fly STL to ATL: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 94.0% of the time and Wednesday flights 92.0%, against 84.6% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.3%. That gap is worth roughly 73 fewer late arrivals for every thousand flights.
Key figures
On time
84.6%
Arrivals under 15 minutes late, of 3,600 completed flights
Avg delay
71 min
Across delayed arrivals only, not all flights
Cancelled
1.63%
National rate is 1.89%
Best carrier
Delta
89.5% on time across 2,348 flights
These figures cover 3,673 flights between September 2025 and August 2026. The median arrival is 12 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Which airline is most reliable on STL to ATL
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 89.5% of the time; Southwest Airlines manages 79.2%. Sample sizes sit next to every figure, because a two-point gap across 1,091 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 2,348 | 89.5% | 77 min | 1.87% | A |
| Southwest Airlines | 1,091 | 79.2% | 54 min | 1.10% | B |
| Frontier Airlinesthin sample | 234 | 60.7% | 96 min | 1.71% | D |
Delta leads Southwest by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on STL 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.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Best ways to make this trip
The most reliable ways to fly St. Louis 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. STL → ATLSt. Louis to Atlanta | Delta Air Lines | 87.8% | 89.5% | 1.87% | 5am–8am, Wed | DL 1536 07:05 |
| 2. STL → ATLSt. Louis to Atlanta | Southwest Airlines | 78.3% | 79.2% | 1.10% | 11am–2pm, Wed | — |
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 30 points, against 10 points between the best and worst carrier.
- 5am–8am733 flights94.0%
- 8am–11am770 flights93.6%
- 11am–2pm629 flights87.1%
- 2pm–5pm596 flights76.5%
- 5pm–8pm837 flights74.7%
- 8pm–5am108 flights63.9%
Scale runs 55% to 100%.
The 8pm–5am window is where this operation falls apart: 63.9% on time, against 94.0% for the 5am–8am 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 837 flights scheduled in it.
Explore
Filter STL 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 STL to ATL, the best departure window is 5am–8am at 94.0% on time and the worst is 8pm–5am at 63.9%, a wide gap of 30.1 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am94.0%
- 8–11am93.6%
- 11am–2pm87.1%
- 2–5pm76.5%
- 5–8pm74.7%
- 8pm–5am63.9%
best all US flightsScale 55% to 100%.
Across the year
When delays peak on this route
This route's year swings by 18 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.
July is the worst month at 76.6% on time, 18 points below September, the best at 95.0%. 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. October was the busiest month here, with 348 flights.
Across the week, Wednesday is the strongest day at 92.0% on time and Sunday the weakest at 78.6%, a spread of 13 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 44% of the 39,000 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Late-arriving aircraft
- 34%Carrier
- 18%National Airspace System
- 5%Extreme weather
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 39,000 reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 39,207 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 94.0% on time here.
Cancellations sit at 1.63% against a national 1.89%, which is ordinary. Diversions add another 0.35%.
Connections and stage length
What a delay here actually costs
5.4% 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 484 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg runs 81.8% on time across 3,678 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 3,673 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. September runs 95.0% on time and July 76.6%, a swing of 18 points. If the dates move at all, move them out of July before you think about anything else. 3,600 completed flights over 12 months sit behind that.
Common questions
STL to ATL questions
How often is STL to ATL delayed?
Roughly one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 15.4% of the 3,673 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 STL to ATL?
Delta Air Lines leads at 89.5% on time across 2,348 flights. Southwest Airlines is at the other end on 79.2%, a gap of 10 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 STL to ATL?
The 5am–8am departure window is the strongest at 94.0% on time. The 8pm–5am window is the weakest at 63.9%, 30 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 July delays on STL to ATL?
July is the weakest month at 76.6% on time, compared with 95.0% in September. Across the year that is 18 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 STL — the return legseparate record
- St. Louis Lambert International (STL) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Delta Air Lines on STL to ATL89.5%
- Southwest Airlines on STL to ATL79.2%
- Frontier Airlines on STL to ATL60.7%
- STL to DEN, a related route75.0%
- LGA to ATL, a related route75.5%
- STL to ORD, a related route72.5%
- Delta Air Lines on-time record89.5%
- Southwest Airlines on-time record79.2%
- Frontier Airlines on-time record60.7%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. STL to ATL and ATL to STL are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Embed STL to ATL’s on-time badge on your site
Paste this into a web page. The badge shows the current on-time rate, cancellation rate and grade, and updates every month. Preview it, or build a badge for another route or airport.
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.