Route reliability record
BOS→CHS
Boston to Charleston
- Flights
- 1,130
- Period
- July 2025 to June 2026
- Distance
- 818 mi
- Carriers
- 3
This route lands a B, level with the national rate of 77.6%. Roughly one flight in four 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 1,130 BOS to CHS flights, of which Delta Air Lines flew 390 at 78.0% on time.
Best time to fly BOS to CHS: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 84.7% of the time and Wednesday flights 84.8%, against 77.2% 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
77.2%
Arrivals under 15 minutes late, of 1,107 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
1.77%
National rate is 1.81%
Best carrier
Delta
78.0% on time across 390 flights
These figures cover 1,130 flights between July 2025 and June 2026. Beyond the headline rate, 8.7% 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 BOS to CHS
The two carriers here are closely matched: 2 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 89 | 84.3% | 58 min | 0.00% | B+ |
| Delta Air Lines | 390 | 78.0% | 73 min | 2.31% | B |
| JetBlue Airways | 651 | 75.8% | 66 min | 1.69% | B |
No carrier stands out. Delta tops the table at 78.0%, 2 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on BOS to CHS
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.
Best ways to make this trip
The most reliable ways to fly Boston to Charleston
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. BOS → CHSBoston to Charleston | Delta Air Lines | 76.2% | 78.0% | 2.31% | 8am–11am, Wed | DL 2785 12:55 |
| 2. BOS → CHSBoston to Charleston | JetBlue Airways | 74.5% | 75.8% | 1.69% | 5am–8am, Tue | B6 267 09:55 |
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 2 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am140 flights84.7%
- 8am–11am327 flights83.5%
- 11am–2pm410 flights79.6%
- 2pm–5pm126 flights67.2%
- 5pm–8pm127 flights54.5%
- 8pm–5am—
Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 54.5% on time, against 84.7% 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 11am–2pm window is the busiest, with 410 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 24 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.
December is the weak month at 61.6% on time, against 85.5% in May. 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. May was the busiest month here, with 124 flights.
Across the week, Wednesday is the strongest day at 84.8% on time and Sunday the weakest at 73.4%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 17,000 reported delay minutes.
- 39%Late-arriving aircraft
- 36%Carrier
- 22%National Airspace System
- 3%Extreme weather
39% 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 17,000 reported delay minutes here, that single category outweighs weather by 13 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 17,075 reported delay minutes.
The largest share of delay minutes, 36%, 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 6,167 of the 17,000 delay minutes reported here.
Cancellations sit at 1.77% against a national 1.81%, which is ordinary. Diversions add another 0.27%.
Connections and stage length
What a delay here actually costs
8.7% of arrivals land an hour or more late, close to the national 8.1%. 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 last about an hour, which a normal layover absorbs.
The 818 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 is a different operation and performs like one: it runs 71.3% on time across 1,131 flights, 6 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 6 points of difference.
The sample behind these figures is 1,130 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 CHS 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. May runs 85.5% on time and December 61.6%, a swing of 24 points. If the dates move at all, move them out of December before you think about anything else. 1,107 completed flights over 12 months sit behind that.
Common questions
BOS to CHS questions
How often is BOS to CHS delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.8% of the 1,130 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on BOS to CHS?
Delta Air Lines leads at 78.0% on time across 390 flights. JetBlue Airways is at the other end on 75.8%, a gap of 2 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 BOS to CHS?
The 5am–8am departure window is the strongest at 84.7% on time. The 5pm–8pm window is the weakest at 54.5%, 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 December delays on BOS to CHS?
December is the weakest month at 61.6% on time, compared with 85.5% in May. Across the year that is 24 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
- CHS to BOS — the return legseparate record
- Boston Logan International (BOS) delay statistics
- Delta Air Lines on BOS to CHS78.0%
- JetBlue Airways on BOS to CHS75.8%
- BOS to DCA, a related route74.0%
- ATL to CHS, a related route83.7%
- BOS to ORD, a related route72.7%
- Republic Airways on-time record84.3%
- Delta Air Lines on-time record78.0%
- JetBlue Airways on-time record75.8%
- 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. BOS to CHS and CHS to BOS 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.