Route reliability record
GSP→MIA
Greer to Miami
- Flights
- 725
- Period
- July 2025 to June 2026
- Distance
- 637 mi
- Carriers
- 2
This route lands a B, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 725 GSP to MIA flights, with a median arrival 7 minutes early.
Best time to fly GSP to MIA: a 5am–8am departure, ideally on a Monday. Flights in that window arrived on time 88.1% of the time and Monday flights 85.6%, against 80.4% for the route overall.
The US average over the same twelve months is 77.6%, 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
80.4%
Arrivals under 15 minutes late, of 716 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
1.24%
National rate is 1.81%
Best carrier
Envoy
80.3% on time across 704 flights
These figures cover 725 flights between July 2025 and June 2026. The median arrival is 7 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 MIA
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 |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 21 | 84.2% | 34 min | 9.52% | B− |
| Envoy Air | 704 | 80.3% | 62 min | 0.99% | B+ |
Flight by flight
Flights on GSP to MIA
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.
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 26 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–8am364 flights88.1%
- 8am–11am15 flights—
- 11am–2pm43 flights83.3%
- 2pm–5pm35 flights82.9%
- 5pm–8pm174 flights73.5%
- 8pm–5am94 flights61.7%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 61.7% on time, against 88.1% 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 5am–8am window is the busiest, with 364 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 37 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.
January is the weak month at 59.7% on time, against 96.9% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. January was the busiest month here, with 67 flights.
Across the week, Monday is the strongest day at 85.6% on time and Saturday the weakest at 75.2%. 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 50% of the 8,590 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.
- 50%Carrier
- 38%Late-arriving aircraft
- 11%National Airspace System
- 2%Extreme weather
38% 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 8,590 reported delay minutes here, that single category outweighs weather by 22 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 8,590 reported delay minutes.
The largest share of delay minutes, 50%, 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 4,266 of the 8,590 delay minutes reported here.
Cancellations sit at 1.24% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
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.
The 637 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 81.0% on time across 726 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 725 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 MIA after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 725 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 80.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 716 completed flights over 12 months sit behind that.
Common questions
GSP to MIA questions
How often is GSP to MIA delayed?
About 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 19.6% of the 725 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is GSP to MIA compared with the rest of the country?
80.4% of flights arrive on time here against a national 77.6%, a difference of 3 points in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on GSP to MIA?
The 5am–8am departure window is the strongest at 88.1% on time. The 8pm–5am window is the weakest at 61.7%, 26 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 January delays on GSP to MIA?
January is the weakest month at 59.7% on time, compared with 96.9% in September. Across the year that is 37 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
- MIA to GSP — the return legseparate record
- Miami International (MIA) delay statistics
- GSP to ATL, a related route90.4%
- ATL to MIA, a related route71.0%
- GSP to ORD, a related route74.9%
- Republic Airways on-time record84.2%
- Envoy Air on-time record80.3%
- 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 MIA and MIA to GSP 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.