Route reliability record
MIA→GSP
Miami to Greer
- Flights
- 726
- 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 40 minutes on average. That is a workable record, not a spotless one. That rests on 726 MIA to GSP flights, with a median arrival 7 minutes early.
Best time to fly MIA to GSP: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 90.9% of the time and Tuesday flights 89.2%, against 81.0% 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
81.0%
Arrivals under 15 minutes late, of 716 completed flights
Avg delay
41 min
Across delayed arrivals only, not all flights
Cancelled
1.24%
National rate is 1.81%
Best carrier
Envoy
81.1% on time across 705 flights
These figures cover 726 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 MIA to GSP
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 |
|---|---|---|---|---|---|
| Envoy Air | 705 | 81.1% | 41 min | 0.99% | B+ |
| Republic Airwaysthin sample | 21 | 78.9% | 48 min | 9.52% | B− |
Flight by flight
Flights on MIA to GSP
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 17 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–8am—
- 8am–11am56 flights90.9%
- 11am–2pm11 flights—
- 2pm–5pm196 flights79.7%
- 5pm–8pm96 flights74.0%
- 8pm–5am367 flights81.8%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 90.9% of the time, against 74.0% for the evening window. That is 17 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 367 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 32 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 62.3% on time, against 93.8% 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, Tuesday is the strongest day at 89.2% on time and Sunday the weakest at 67.0%. 22 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 5,556 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
- 31%National Airspace System
- 19%Carrier
- 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 5,556 reported delay minutes here, that single category outweighs weather by 10 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 5,556 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 90.9% on time here.
Cancellations sit at 1.24% against a national 1.81%, which is ordinary. Diversions add another 0.14%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 3.9% 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 80.4% on time across 725 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. 726 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 GSP after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 726 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 81.0% 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
MIA to GSP questions
How often is MIA to GSP 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 19.0% of the 726 flights in this analysis, against 22.4% nationally. Delayed flights are late by about 40 minutes on average.
How reliable is MIA to GSP compared with the rest of the country?
81.0% 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 MIA to GSP?
The 8am–11am departure window is the strongest at 90.9% on time. The 5pm–8pm window is the weakest at 74.0%, 17 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 MIA to GSP?
January is the weakest month at 62.3% on time, compared with 93.8% in September. Across the year that is 32 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
- GSP to MIA — the return legseparate record
- Miami International (MIA) delay statistics
- MIA to ATL, a related route73.7%
- ATL to GSP, a related route83.9%
- MIA to LGA, a related route68.0%
- Envoy Air on-time record81.1%
- Republic Airways on-time record78.9%
- 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. MIA to GSP and GSP to MIA 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.