Route reliability record
IAD→CHS
Washington to Charleston
- Flights
- 761
- Period
- July 2025 to June 2026
- Distance
- 442 mi
- Carriers
- 2
This route earns an A. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 761 IAD to CHS flights, with a median arrival 7 minutes early.
Best time to fly IAD to CHS: a 8am–11am departure, ideally on a Wednesday. Flights in that window arrived on time 93.6% of the time and Wednesday flights 91.7%, against 86.8% for the route overall.
Set against the rest of the country, this route's record is 9 points better than the US average of 77.6%. That gap is worth roughly 92 fewer late arrivals for every thousand flights.
Key figures
On time
86.8%
Arrivals under 15 minutes late, of 752 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
1.18%
National rate is 1.81%
Best carrier
United
89.5% on time across 463 flights
These figures cover 761 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 IAD to CHS
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 |
|---|---|---|---|---|---|
| United Airlines | 463 | 89.5% | 88 min | 0.86% | A+ |
| Republic Airwaysthin sample | 298 | 82.6% | 58 min | 1.68% | B |
Best ways to make this trip
The most reliable ways to fly Washington to Charleston
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 4 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. IAD → CHSWashington to Charleston | United Airlines | 88.7% | 89.5% | 0.86% | 8am–11am, Thu | — |
| 2. BWI → CHSBaltimore to Charleston | Southwest Airlines | 79.5% | 80.6% | 1.38% | 8am–11am, Wed (route) | — |
| 3. DCA → CHSWashington to Charleston | Republic Airways | 77.9% | 80.7% | 3.47% | 8pm–5am, Tue | — |
| 4. DCA → CHSWashington to Charleston | PSA Airlines | 65.6% | 68.6% | 4.35% | 8am–11am, Sat | — |
| 5. DCA → CHSWashington to Charleston | American Airlines | 63.6% | 65.0% | 2.19% | 8am–11am, Sat | — |
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 27 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–11am281 flights93.6%
- 11am–2pm360 flights86.8%
- 2pm–5pm—
- 5pm–8pm88 flights66.7%
- 8pm–5am32 flights81.2%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 93.6% of the time, against 66.7% for the evening window. That is 27 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 360 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 19 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 75.0% on time, against 94.0% 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. March was the busiest month here, with 92 flights.
Across the week, Wednesday is the strongest day at 91.7% on time and Friday the weakest at 80.2%. 12 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 50% of the 7,196 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%Late-arriving aircraft
- 30%Carrier
- 18%National Airspace System
- 2%Extreme weather
50% 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 7,196 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 7,196 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 93.6% on time here.
Cancellations sit at 1.18% 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.
At 442 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 8am–11am window matters as much as it does.
The return leg runs 84.8% on time across 759 flights, within 2 points 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. 761 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 CHS after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 761 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 86.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 752 completed flights over 12 months sit behind that.
Common questions
IAD to CHS questions
How often is IAD to CHS delayed?
About one flight in eight arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 13.2% of the 761 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
How reliable is IAD to CHS compared with the rest of the country?
86.8% of flights arrive on time here against a national 77.6%, a difference of 9 points in its favour. That is worth a A on this site's grading scale.
What time of day has the fewest delays on IAD to CHS?
The 8am–11am departure window is the strongest at 93.6% on time. The 5pm–8pm window is the weakest at 66.7%, 27 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 IAD to CHS?
December is the weakest month at 75.0% on time, compared with 94.0% in September. Across the year that is 19 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 IAD — the return legseparate record
- Washington Dulles International (IAD) delay statistics
- United Airlines on IAD to CHS89.5%
- Republic Airways on IAD to CHS82.6%
- IAD to ATL, a related route79.2%
- ATL to CHS, a related route83.7%
- IAD to DEN, a related route81.7%
- United Airlines on-time record89.5%
- Republic Airways on-time record82.6%
- 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. IAD to CHS and CHS to IAD 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.