Route reliability record
ATL→LAS
Atlanta to Las Vegas
- Flights
- 4,843
- Period
- June 2025 to May 2026
- Distance
- 1,747 mi
- Carriers
- 4
This route sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.4%. The late ones land about an hour behind schedule. That rests on 4,843 flights, of which Southwest Airlines flew 720 at 77.0% on time.
Southwest Airlines is the most reliable of the three carriers covered here at 77.0% on time across 720 flights.
Key figures
On time
74.9%
Arrivals under 15 minutes late, of 4,786 completed flights
Avg delay
60 min
Across delayed arrivals only, not all flights
Cancelled
0.95%
National rate is 1.80%
Best carrier
Southwest
77.0% on time across 720 flights
These figures cover 4,843 flights between June 2025 and May 2026. Beyond the headline rate, 8.1% 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 LAS
The choice of carrier is not cosmetic here. Southwest Airlines arrives on time 77.0% of the time; Frontier Airlines manages 62.9%. Sample sizes sit next to every figure, because a two-point gap across 544 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 223 | 78.7% | 68 min | 0.90% | B+ |
| Southwest Airlines | 720 | 77.0% | 53 min | 0.28% | B+ |
| Delta Air Lines | 3,356 | 76.1% | 55 min | 0.80% | B+ |
| Frontier Airlines | 544 | 62.9% | 88 min | 2.76% | D |
The spread between Southwest and Frontier is 14 points, wide enough that it should decide the booking. On a hundred trips that is 14 more arrivals inside the on-time window.
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 24 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am507 flights90.0%
- 8am–11am910 flights82.4%
- 11am–2pm674 flights78.7%
- 2pm–5pm528 flights73.7%
- 5pm–8pm1,265 flights68.3%
- 8pm–5am959 flights66.5%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.0% of the time, against 66.5% for the overnight window. That is 24 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.
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.
June is the worst month at 62.7% on time, 18 points below November, the best at 80.6%. 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.
Across the week, Wednesday is the strongest day at 82.6% on time and Monday the weakest at 72.3%. 10 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. Carrier accounts for 44% of the 72,000 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.
- 44%Carrier
- 30%Late-arriving aircraft
- 21%National Airspace System
- 5%Extreme weather
- 0%Security
The largest share of delay minutes, 44%, 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 32,000 of the 72,000 delay minutes reported here.
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 90.0% on time here.
Cancellations sit at 0.95% against a national 1.80%, which is ordinary. Diversions add another 0.23%.
Connections and stage length
What a delay here actually costs
8.1% of arrivals land an hour or more late, close to the national 8.2%. 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 1,747 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 84.2% on time across 4,840 flights, 9 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 9 points of difference.
The sample behind these figures is 4,843 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. November runs 80.6% on time and June 62.7%, a swing of 18 points. If the dates move at all, move them out of June before you think about anything else.
Common questions
ATL to LAS questions
How often is ATL to LAS delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 25.1% of the 4,843 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on ATL to LAS?
Southwest Airlines leads at 77.0% on time across 720 flights. Frontier Airlines is at the other end on 62.9%, a gap of 14 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 LAS?
The 5am–8am departure window is the strongest at 90.0% on time. The 8pm–5am window is the weakest at 66.5%, 24 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 LAS?
June is the weakest month at 62.7% on time, compared with 80.6% in November. 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
- LAS to ATL — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Harry Reid International (LAS) delay statistics
- Spirit Airlines on-time record78.7%
- Southwest Airlines on-time record77.0%
- Delta Air Lines on-time record76.1%
- The best time of day to fly, according to 7.05 million flight records
- Connecting flights: how much buffer the data says you need
Direction matters. ATL to LAS and LAS 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, June 2025 to May 2026. Updated monthly. How this data is collected.