Route reliability record
GSP→ATL
Greer to Atlanta
- Flights
- 2,818
- Period
- July 2025 to June 2026
- Distance
- 153 mi
- Carriers
- 1
This route earns a A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 13 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 2,818 flights, with a median arrival 15 minutes early.
Set against the rest of the country, this route's record is 13 points better than the US average of 77.6%. That gap is worth roughly 128 fewer late arrivals for every thousand flights.
Key figures
On time
90.4%
Arrivals under 15 minutes late, of 2,772 completed flights
Avg delay
83 min
Across delayed arrivals only, not all flights
Cancelled
1.53%
National rate is 1.81%
Best carrier
Delta
90.4% on time across 2,818 flights
These figures cover 2,818 flights between July 2025 and June 2026. The median arrival is 15 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 GSP to ATL
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 | 2,818 | 90.4% | 83 min | 1.53% | A |
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 13 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am825 flights95.1%
- 8am–11am597 flights92.7%
- 11am–2pm447 flights90.9%
- 2pm–5pm427 flights86.4%
- 5pm–8pm424 flights83.1%
- 8pm–5am98 flights82.5%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 95.1% of the time, against 82.5% for the overnight window. That is 13 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 825 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 13 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.
April is the best month on the calendar at 95.4% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. May was the busiest month here, with 254 flights.
Across the week, Wednesday is the strongest day at 94.2% on time and Monday the weakest at 87.3%. 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 45% of the 22,000 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.
- 45%Late-arriving aircraft
- 33%Carrier
- 18%National Airspace System
- 4%Extreme weather
45% 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 22,000 reported delay minutes here, that single category outweighs weather by 12 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 22,030 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 95.1% on time here.
Cancellations sit at 1.53% against a national 1.81%, which is ordinary. Diversions add another 0.11%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.3% land an hour or more behind schedule, against 8.1% 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 153 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 is a different operation and performs like one: it runs 83.9% on time across 2,817 flights, 7 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 7 points of difference.
The sample behind these figures is 2,818 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. April runs 95.4% on time and March 82.7%, a swing of 13 points. If the dates move at all, move them out of March before you think about anything else. 2,772 completed flights over 12 months sit behind that.
Common questions
GSP to ATL questions
How often is GSP to ATL delayed?
About one flight in ten arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 9.6% of the 2,818 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
How reliable is GSP to ATL compared with the rest of the country?
90.4% of flights arrive on time here against a national 77.6%, a difference of 13 points in its favour. That is worth a A on this site's grading scale.
What time of day has the fewest delays on GSP to ATL?
The 5am–8am departure window is the strongest at 95.1% on time. The 8pm–5am window is the weakest at 82.5%, 13 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 GSP to ATL?
March is the weakest month at 82.7% on time, compared with 95.4% in April. Across the year that is 13 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 GSP — the return legseparate record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Delta Air Lines on-time record90.4%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. GSP to ATL and ATL to GSP 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.