Route reliability record
IAD→CMH
Washington to Columbus
- Flights
- 936
- Period
- September 2025 to August 2026
- Distance
- 299 mi
- Carriers
- 2
This route lands a B, 5 points better than the national rate of 77.3%. 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 rests on 936 IAD to CMH flights, of which United Airlines flew 409 at 83.0% on time.
Best time to fly IAD to CMH: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 90.1% of the time and Tuesday flights 87.9%, 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 77.3%. That gap is worth roughly 48 fewer late arrivals for every thousand flights.
Key figures
On time
82.1%
Arrivals under 15 minutes late, of 924 completed flights
Avg delay
74 min
Across delayed arrivals only, not all flights
Cancelled
1.18%
National rate is 1.89%
Best carrier
United
83.0% on time across 409 flights
These figures cover 936 flights between September 2025 and August 2026. The median arrival is 9 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.
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Carrier by carrier
Which airline is most reliable on IAD to CMH
The two carriers here are closely matched: 2 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 | 409 | 83.0% | 69 min | 0.24% | B+ |
| Republic Airways | 527 | 81.4% | 77 min | 1.90% | B |
No carrier stands out. United tops the table at 83.0%, 2 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.
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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 | 82.8% | 83.0% | 0.24% | 11am–2pm, Wed | — |
| 2. IAD → CMHWashington to Columbus | Republic Airways | 79.9% | 81.4% | 1.90% | 11am–2pm, Tue | YX 3646 22:10 |
| 3. DCA → CMHWashington to Columbus | Republic Airways | 78.0% | 80.1% | 2.63% | 5am–8am, Sat | — |
| 4. BWI → CMHBaltimore to Columbus | Southwest Airlines | 76.7% | 77.9% | 1.52% | 8am–11am, Tue | — |
| 5. DCA → CMHWashington to Columbus | PSA Airlines | 67.2% | 73.7% | 8.79% | 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 14 points, against 2 points between the best and worst carrier.
- 5am–8am—
- 8am–11am175 flights90.1%
- 11am–2pm188 flights87.2%
- 2pm–5pm22 flights—
- 5pm–8pm239 flights76.1%
- 8pm–5am312 flights81.2%
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 90.1% of the time, against 76.1% 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 312 flights scheduled in it.
Explore
Filter IAD to CMH by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On IAD to CMH, the best departure window is 8am–11am at 90.1% on time and the worst is 5pm–8pm at 76.1%, a wide gap of 14.0 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am—
- 8–11am90.1%
- 11am–2pm87.2%
- 2–5pm—
- 5–8pm76.1%
- 8pm–5am81.2%
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 27 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.
August is the worst month at 69.8% on time, 27 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, Tuesday is the strongest day at 87.9% on time and Sunday the weakest at 76.5%, a spread of 11 points.
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 12,000 reported delay minutes.
- 41%Late-arriving aircraft
- 38%Carrier
- 17%National Airspace System
- 3%Extreme weather
41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 12,000 reported delay minutes here, that single category outweighs weather by 14 to one. The split is drawn from 12,185 reported delay minutes.
The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 4,664 of the 12,000 delay minutes reported here.
Cancellations sit at 1.18% against a national 1.89%, which is ordinary. Diversions add another 0.11%.
Connections and stage length
What a delay here actually costs
6.9% of arrivals land an hour or more late, close to the national 8.3%, so 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 84.9% on time across 935 flights, within 3 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. 936 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. 936 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. 924 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 936 flights in this analysis, against 22.7% 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 83.0% on time across 409 flights. Republic Airways is at the other end on 81.4%, a gap of 2 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 90.1% on time. The 5pm–8pm window is the weakest at 76.1%, 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 August delays on IAD to CMH?
August is the weakest month at 69.8% on time, compared with 96.5% in April. Across the year that is 27 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 CMH83.0%
- Republic Airways on IAD to CMH81.4%
- IAD to ATL, a related route78.0%
- ORD to CMH, a related route73.5%
- IAD to DEN, a related route83.1%
- United Airlines on-time record83.0%
- Republic Airways on-time record81.4%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.