Route reliability record
CMH→IAD
Columbus to Washington
- Flights
- 1,061
- Period
- July 2025 to June 2026
- Distance
- 299 mi
- Carriers
- 2
This route earns a B. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 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 1,061 CMH to IAD flights, of which Republic Airways flew 673 at 86.9% on time.
Best time to fly CMH to IAD: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 94.2% of the time and Saturday flights 91.4%, against 84.3% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.6%. That gap is worth roughly 67 fewer late arrivals for every thousand flights.
Key figures
On time
84.3%
Arrivals under 15 minutes late, of 1,044 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
1.60%
National rate is 1.81%
Best carrier
Republic
86.9% on time across 673 flights
These figures cover 1,061 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 CMH to IAD
The choice of carrier is not cosmetic here. Republic Airways arrives on time 86.9% of the time; United Airlines manages 79.7%. Sample sizes sit next to every figure, because a two-point gap across 388 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airways | 673 | 86.9% | 73 min | 2.08% | A |
| United Airlines | 388 | 79.7% | 87 min | 0.77% | B+ |
Republic leads United by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on CMH to IAD
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 Columbus to Washington
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. 3 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. CMH → BWIColumbus to Baltimore | Southwest Airlines | 85.7% | 87.4% | 1.90% | 5am–8am, Tue | — |
| 2. CMH → IADColumbus to Washington | Republic Airways | 85.1% | 86.9% | 2.08% | 5am–8am, Thu | YX 3430 06:00 |
| 3. CMH → IADColumbus to Washington | United Airlines | 79.1% | 79.7% | 0.77% | 8am–11am, Sat | — |
| 4. CMH → DCAColumbus to Washington | Republic Airways | 65.4% | 67.8% | 3.60% | 8am–11am, Sat | — |
| 5. CMH → DCAColumbus to Washington | PSA Airlines | 60.8% | 65.0% | 6.46% | 5am–8am, Tue | — |
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 25 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am348 flights94.2%
- 8am–11am198 flights87.2%
- 11am–2pm22 flights—
- 2pm–5pm217 flights69.2%
- 5pm–8pm123 flights74.6%
- 8pm–5am153 flights84.8%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 94.2% of the time, against 69.2% for the afternoon window. That is 25 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 348 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 21 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.
July is the worst month at 74.0% on time, 21 points below April, the best at 95.3%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. September was the busiest month here, with 136 flights.
Across the week, Saturday is the strongest day at 91.4% on time and Monday the weakest at 75.3%. 16 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 43% of the 13,000 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.
- 43%Late-arriving aircraft
- 38%Carrier
- 15%National Airspace System
- 4%Extreme weather
43% 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 13,000 reported delay minutes here, that single category outweighs weather by 11 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 13,026 reported delay minutes.
The largest share of delay minutes, 38%, 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 4,902 of the 13,000 delay minutes reported here.
Cancellations sit at 1.60% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here actually costs
5.7% 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 a little over an hour, which a normal layover absorbs.
At 299 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 5am–8am window matters as much as it does.
The return leg runs 82.1% on time across 1,061 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. 1,061 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 IAD after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,061 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 84.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,044 completed flights over 12 months sit behind that.
Common questions
CMH to IAD questions
How often is CMH to IAD delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 15.7% of the 1,061 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on CMH to IAD?
Republic Airways leads at 86.9% on time across 673 flights. United Airlines is at the other end on 79.7%, a gap of 7 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 CMH to IAD?
The 5am–8am departure window is the strongest at 94.2% on time. The 2pm–5pm window is the weakest at 69.2%, 25 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 July delays on CMH to IAD?
July is the weakest month at 74.0% on time, compared with 95.3% in April. Across the year that is 21 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
- IAD to CMH — the return legseparate record
- John Glenn Columbus International (CMH) delay statistics
- Washington Dulles International (IAD) delay statistics
- Republic Airways on CMH to IAD86.9%
- United Airlines on CMH to IAD79.7%
- CMH to ORD, a related route74.5%
- ATL to IAD, a related route76.5%
- CMH to ATL, a related route85.9%
- Republic Airways on-time record86.9%
- United Airlines on-time record79.7%
- 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. CMH to IAD and IAD to CMH 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.