Route reliability record
IAD→CMH
Washington to Columbus
- Flights
- 1,061
- Period
- July 2025 to June 2026
- Distance
- 299 mi
- Carriers
- 2
This route lands a B, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,061 IAD to CMH flights, of which United Airlines flew 389 at 85.0% on time.
Best time to fly IAD to CMH: a 8am–11am departure, ideally on a Saturday. Flights in that window arrived on time 89.8% of the time and Saturday flights 86.7%, against 82.1% for the route overall.
Set against the rest of the country, this route's record is 5 points better than the US average of 77.6%. That gap is worth roughly 45 fewer late arrivals for every thousand flights.
Key figures
On time
82.1%
Arrivals under 15 minutes late, of 1,045 completed flights
Avg delay
78 min
Across delayed arrivals only, not all flights
Cancelled
1.41%
National rate is 1.81%
Best carrier
United
85.0% on time across 389 flights
These figures cover 1,061 flights between July 2025 and June 2026. The median arrival is 8 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 CMH
The two carriers here are closely matched: 5 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 |
|---|---|---|---|---|---|
| United Airlines | 389 | 85.0% | 64 min | 0.26% | A+ |
| Republic Airways | 672 | 80.4% | 84 min | 2.08% | B |
No carrier stands out. United tops the table at 85.0%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on IAD to CMH
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 Washington to Columbus
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. IAD → CMHWashington to Columbus | United Airlines | 84.8% | 85.0% | 0.26% | 8am–11am, Wed | — |
| 2. IAD → CMHWashington to Columbus | Republic Airways | 78.7% | 80.4% | 2.08% | 8am–11am, Sat | YX 3646 22:10 |
| 3. DCA → CMHWashington to Columbus | Republic Airways | 78.5% | 80.7% | 2.68% | 5am–8am, Tue | YX 4700 10:00 |
| 4. BWI → CMHBaltimore to Columbus | Southwest Airlines | 77.3% | 78.9% | 2.08% | 8am–11am, Tue | — |
| 5. DCA → CMHWashington to Columbus | PSA Airlines | 67.3% | 71.2% | 5.49% | 8am–11am, 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 14 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am199 flights89.8%
- 11am–2pm216 flights86.6%
- 2pm–5pm22 flights—
- 5pm–8pm277 flights75.5%
- 8pm–5am347 flights81.9%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 89.8% of the time, against 75.5% for the evening window. That is 14 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 347 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 31 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 65.8% on time, 31 points below April, the best at 96.5%. 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 86.7% on time and Sunday the weakest at 77.6%. 9 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 49% of the 15,000 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.
- 49%Late-arriving aircraft
- 33%Carrier
- 15%National Airspace System
- 3%Extreme weather
49% 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 15,000 reported delay minutes here, that single category outweighs weather by 15 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 14,575 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 89.8% on time here.
Cancellations sit at 1.41% against a national 1.81%, which is ordinary. Diversions add another 0.09%.
Connections and stage length
What a delay here actually costs
6.8% 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 8am–11am window matters as much as it does.
The return leg runs 84.3% 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 CMH 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 82.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,045 completed flights over 12 months sit behind that.
Common questions
IAD to CMH questions
How often is IAD to CMH 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 17.9% 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 IAD to CMH?
United Airlines leads at 85.0% on time across 389 flights. Republic Airways is at the other end on 80.4%, a gap of 5 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 IAD to CMH?
The 8am–11am departure window is the strongest at 89.8% on time. The 5pm–8pm window is the weakest at 75.5%, 14 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 IAD to CMH?
July is the weakest month at 65.8% on time, compared with 96.5% in April. Across the year that is 31 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
- CMH to IAD — the return legseparate record
- Washington Dulles International (IAD) delay statistics
- John Glenn Columbus International (CMH) delay statistics
- United Airlines on IAD to CMH85.0%
- Republic Airways on IAD to CMH80.4%
- IAD to ATL, a related route79.2%
- ORD to CMH, a related route73.1%
- IAD to DEN, a related route81.7%
- United Airlines on-time record85.0%
- Republic Airways on-time record80.4%
- 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 CMH and CMH 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.