Route reliability record

CLT→BOS

Charlotte to Boston

Flights: 4,016
Period: July 2025 to June 2026
Distance: 728 mi
Carriers: 4

This route lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrive 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 4,016 flights, of which Republic Airways flew 1,199 at 81.9% on time.

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.

On time

76.2%

Arrivals under 15 minutes late, of 3,912 completed flights

Avg delay

66 min

Across delayed arrivals only, not all flights

Cancelled

2.49%

National rate is 1.81%

Best carrier

Republic

81.9% on time across 1,199 flights

These figures cover 4,016 flights between July 2025 and June 2026. Beyond the headline rate, 9.2% 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 CLT to BOS

The choice of carrier is not cosmetic here. Republic Airways arrives on time 81.9% of the time; American Airlines manages 73.8%. Sample sizes sit next to every figure, because a two-point gap across 2,735 flights means less than a ten-point one.

On-time performance by carrier on CLT to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airways	1,199	81.9%	73 min	3.00%	B
American Airlines	2,735	73.8%	63 min	2.23%	C
Spirit Airlinesthin sample	77	73.7%	87 min	1.30%	C
Envoy Airthin sample	5	66.7%	144 min	40.00%	C−

Republic leads American by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

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 28 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am550 flights91.9%
8am–11am724 flights88.9%
11am–2pm783 flights77.5%
2pm–5pm651 flights67.4%
5pm–8pm901 flights63.5%
8pm–5am407 flights71.3%

Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 63.5% on time, against 91.9% 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 5pm–8pm window is the busiest, with 901 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.

Darker means more delays. Figures are on-time percentages.November best, September worst

November is the best month on the calendar at 83.7% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. October was the busiest month here, with 370 flights.

Across the week, Saturday is the strongest day at 80.6% on time and Sunday the weakest at 70.9%. 10 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 62,000 reported delay minutes.

Late-arriving aircraft
38%
National Airspace System
30%
Carrier
25%
Extreme weather
7%
Security
0%

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 62,000 reported delay minutes here, that single category outweighs weather by 6 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 61,510 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 91.9% on time here.

Cancellations sit at 2.49% against a national 1.81%, which is ordinary. Diversions add another 0.10%.

Connections and stage length

What a delay here actually costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.2% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

The 728 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 82.6% on time across 4,017 flights, 6 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 6 points of difference.

The sample behind these figures is 4,016 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 83.7% on time and September 60.1%, a swing of 24 points. If the dates move at all, move them out of September before you think about anything else. 3,912 completed flights over 12 months sit behind that.

Common questions

CLT to BOS questions

How often is CLT to BOS 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 23.8% of the 4,016 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on CLT to BOS?

Republic Airways leads at 81.9% on time across 1,199 flights. American Airlines is at the other end on 73.8%, a gap of 8 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 CLT to BOS?

The 5am–8am departure window is the strongest at 91.9% on time. The 5pm–8pm window is the weakest at 63.5%, 28 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 September delays on CLT to BOS?

September is the weakest month at 60.1% on time, compared with 83.7% in November. 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.

Where to go next

Direction matters. CLT to BOS and BOS to CLT 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.

Key figures