Charleston and Jacksonville airports: rarely late, but late for long

When a flight out of Charleston runs late, it runs very late. Over September 2025 to August 2026, late departures from Charleston International averaged 86 minutes behind schedule, and late departures from Jacksonville 85. Of the 60 airports on this site, the two longest averages belonged to Charleston (CHS) and Jacksonville (JAX). The national figure is 73 minutes.

That would be alarming if these flights were often late. They are not. Charleston (CHS) put 78.9% of its departures on time, rank 27 of 60, and Jacksonville (JAX) 79.6%, rank 19, both above the national 77.3%. Both airports are late less often than most; when they are late, it is more likely to be a lost afternoon than a lost half-hour. That combination changes how I would plan a connection from either one more than the headline rate does. As everywhere on this site, the figures are for departures, scored on arrival.

Why the delays run long

The pattern has a likely explanation in how the two airports are served. Neither is a hub. Both are served mostly by the big network airlines flying a handful of daily trips to their hubs, often on regional jets, plus Southwest and JetBlue. When an aircraft breaks down in Charleston or a crew runs out of duty time, there is rarely a spare on the ground; the fix is another aircraft flown in from Atlanta, Charlotte or Chicago, and that takes hours rather than minutes. A Southwest-heavy airport, by contrast, turns a short delay into another short delay. The carrier averages at the two airports fit.

The regional operators, PSA in particular, posted some of the longest delays at both, and even Delta's and American's late flights averaged well over an hour at Charleston. Southwest is the exception at both airports. Its late flights were far shorter than the network carriers', the usual Southwest profile of many small delays and few long ones, so a Southwest delay here is an inconvenience while a regional-jet delay can cost the connection.

The share of late flights that ran an hour or more behind was 40.3% at Charleston and 39.7% at Jacksonville, against 36.6% nationally. The how late do late flights run guide sets that tail against every other airport.

Charleston: Delta's Atlanta run and not much else

American and Delta each run about a fifth of Charleston's departures, with Southwest, United and Republic behind. Delta was the most punctual of the big carriers in this period; JetBlue and Spirit trailed. The standout is a single route: Charleston to Atlanta, flown almost entirely by Delta, ran 88.9% on time, rank 95 of 2,978 routes on this site. Its dawn departure, Delta 3055, was one of the most punctual flight numbers in the country. Charleston to Charlotte, American's hub run, ran 82.7%.

{
 "flights": 3234,
 "completed": 3172,
 "onTimePct": 88.9,
 "veryLatePct": 5.1,
 "avgDelayMin": 78.6,
 "medianArrDelay": -12,
 "cancelPct": 1.73,
 "divertPct": 0.19,
 "causes": {
  "carrier": 0.2947,
  "weather": 0.0488,
  "nas": 0.2202,
  "security": 0.001,
  "lateAircraft": 0.4353
 },
 "byHourBlock": [94.1, 93.2, 90.7, 83.9, 81.5, 75.4 ],
 "byMonth": [91.2, 93, 86.9, 91.1, 87.1, 91.4, 76.8, 81.4, 96.2, 92.1, 92.2, 90 ],
 "byDow": [88.7, 91.1, 94.2, 90.6, 87.5, 88.8, 82 ]
}

This is the file my pipeline writes for the Atlanta route; every Charleston figure above is recomputed from files like it each month.

The Northeast is where Charleston struggles. Charleston to Boston ran 69.5%, to Reagan National 71.8% with 4.98% cancelled, and to LaGuardia cancelled 6.53%, most of it on Republic's LaGuardia flights. On the Washington route, PSA's flights cancelled far more than American's own.

Jacksonville: a more even field

American at Jacksonville is the largest carrier, with Delta, Southwest and United close behind; the four together fly about three flights in four. Delta and United led on punctuality; the low-cost carriers, Allegiant and Frontier, trailed well behind, and JetBlue cancelled more than any big carrier at the airport.

Jacksonville to Atlanta is the busiest route and ran 83.8%, with Delta on the route far ahead of Frontier's. Jacksonville to Dulles was the best big route at 88.8%; Jacksonville to Reagan National the worst at 73.1%. The Dallas route shows the direction effect: Jacksonville to DFW ran 79.3%, but DFW to Jacksonville only 64.8%, because the southbound flights leave a hub that was one of the least punctual in the country. The two directions of a route are separate records in the data, and this pair is a good reminder to check the direction you are actually flying. The best single flights were the dawn departures, among them United 2673 to Newark and Delta 2722 to Atlanta.

The same day at both airports

Both airports have strong mornings and weak nights. Before 8am, Charleston ran 91.6% and Jacksonville 91.8%. After 8pm those fell to 62.5% and 65.2%, the weakest window at each. Jacksonville's morning-to-evening gap of 24.0 points is wider than the national 21.3. The mechanism is the coastal Southeast's summer weather layered on top of aircraft rotation: afternoon thunderstorms here and at the hubs they feed arrive just as the evening departures are loading.

The calendar agrees. July 2026 was the worst month at both: Charleston in July ran 71.6% and Jacksonville in July 71.2%. September 2025 was the best at both, 84.5% and 85.0%, which also means the hurricane season's peak passed without disrupting either airport this year. January 2026 at Charleston had the year's worst cancellation rate at either airport, spread across the Charlotte, Washington, New York and Dallas routes rather than Atlanta, consistent with winter storms at the northern and western ends of the network. It matches the national month: January 2026 had the year's highest cancellation rate, and it was concentrated at Charlotte, Dallas-Fort Worth and Washington National rather than in the snow belt: three of the hubs Charleston's cancelled flights were bound for. One year is one sample; a hurricane landfall on this stretch of coast would dominate any year it happened in.

Sunday is the weakest day at both, 72.5% at Charleston and 73.6% at Jacksonville. Leisure traffic leaving on Sunday afternoon fills the flights that the weather is most likely to hit.

What causes the delay

Late-arriving aircraft account for 45% of Charleston's delay minutes and 43% of Jacksonville's, against 40% nationally. Charleston carries more air traffic delay, 25% against 20% at Jacksonville, consistent with more of its schedule running to the flow-controlled airports of the Northeast. Neither airport's own airspace is the problem.

How I would fly out of Charleston or Jacksonville

Fly the first bank to a hub. A dawn departure to Atlanta from either airport is among the most reliable flying in the Southeast, and it leaves the rest of the day to recover if the connection goes wrong.

Budget time, not just probability. Because late flights here run long, a 60-minute connection that would usually hold elsewhere is riskier from these two airports. Use the connection risk tool and add margin.

Avoid the last flights of the day, especially in summer. After 8pm is the weakest window at both, and a cancelled last departure means a night in town. The summer thunderstorm guide covers June to August.

For Washington, fly to Dulles. From both cities the Dulles route beat the Reagan National route by a wide margin on punctuality: Charleston to Dulles ran 84.7% and Jacksonville's Dulles flights 88.8%. With 4.98% of Charleston's National flights cancelled, I would not put anything time-critical on that route.

Compare the fields: Charleston (CHS) · Jacksonville (JAX) · Atlanta (ATL) · Charlotte (CLT) · Compare any US route