Route reliability record
IAD→ATL
Washington to Atlanta
- Flights
- 4,003
- Period
- September 2025 to August 2026
- Distance
- 534 mi
- Carriers
- 4
This route lands a B, level with the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 4,003 IAD to ATL flights, of which Delta Air Lines flew 2,233 at 79.9% on time.
Best time to fly IAD to ATL: a 8am–11am departure, ideally on a Thursday. Flights in that window arrived on time 86.4% of the time and Thursday flights 82.3%, against 78.0% for the route overall.
Delta Air Lines is the most reliable of the three carriers covered here at 79.9% on time across 2,233 flights.
Key figures
On time
78.0%
Arrivals under 15 minutes late, of 3,895 completed flights
Avg delay
86 min
Across delayed arrivals only, not all flights
Cancelled
2.32%
National rate is 1.89%
Best carrier
Delta
79.9% on time across 2,233 flights
These figures cover 4,003 flights between September 2025 and August 2026. Beyond the headline rate, 9.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on IAD to ATL
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 79.9% of the time; Frontier Airlines manages 68.0%. Sample sizes sit next to every figure, because a two-point gap across 660 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 2,233 | 79.9% | 94 min | 2.82% | B |
| United Airlines | 1,090 | 79.9% | 78 min | 0.73% | B+ |
| Republic Airwaysthin sample | 20 | 78.9% | 41 min | 5.00% | B− |
| Frontier Airlines | 660 | 68.0% | 78 min | 3.18% | C− |
Frontier Airlines cancels 3.2% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Flight by flight
Flights on IAD to ATL
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 Atlanta
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. BWI → ATLBaltimore to Atlanta | Delta Air Lines | 84.2% | 86.0% | 2.11% | 5am–8am, Wed | DL 2950 06:00 |
| 2. IAD → ATLWashington to Atlanta | United Airlines | 79.3% | 79.9% | 0.73% | 8am–11am, Sat | UA 2739 08:15 |
| 3. IAD → ATLWashington to Atlanta | Delta Air Lines | 77.6% | 79.9% | 2.82% | 5am–8am, Thu | DL 2127 06:00 |
| 4. DCA → ATLWashington to Atlanta | Delta Air Lines | 77.2% | 79.2% | 2.55% | 5am–8am, Sat | DL 410 06:00 |
| 5. DCA → ATLWashington to Atlanta | Southwest Airlines | 76.9% | 78.9% | 2.51% | 5am–8am, Wed | — |
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 20 points, against 12 points between the best and worst carrier.
- 5am–8am846 flights79.0%
- 8am–11am760 flights86.4%
- 11am–2pm840 flights82.1%
- 2pm–5pm376 flights77.8%
- 5pm–8pm955 flights69.4%
- 8pm–5am226 flights66.0%
Scale runs 60% to 90%.
Book the morning departure. Flights leaving between 8am–11am arrive on time 86.4% of the time, against 66.0% for the overnight window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 955 flights scheduled in it.
Explore
Filter IAD to ATL 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 ATL, the best departure window is 8am–11am at 86.4% on time and the worst is 8pm–5am at 66.0%, a wide gap of 20.4 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am79.0%
- 8–11am86.4%
- 11am–2pm82.1%
- 2–5pm77.8%
- 5–8pm69.4%
- 8pm–5am66.0%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 25 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 63.0% on time, 25 points below September, the best at 88.2%. 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. May was the busiest month here, with 405 flights.
Across the week, Thursday is the strongest day at 82.3% on time and Sunday the weakest at 72.5%, a spread of 10 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 74,000 reported delay minutes.
- 39%Late-arriving aircraft
- 35%Carrier
- 21%National Airspace System
- 5%Extreme weather
- 0%Security
39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 74,000 reported delay minutes here, that single category outweighs weather by 7 to one. The split is drawn from 73,830 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 26,000 of the 74,000 delay minutes reported here.
Cancellations sit at 2.32% against a national 1.89%, which is ordinary. Diversions add another 0.37%.
Connections and stage length
What a delay here actually costs
9.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 534 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg runs 76.4% on time across 4,005 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.
The sample behind these figures is 4,003 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in ATL after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 88.2% on time and July 63.0%, a swing of 25 points. If the dates move at all, move them out of July before you think about anything else. 3,895 completed flights over 12 months sit behind that.
Common questions
IAD to ATL questions
How often is IAD to ATL delayed?
Roughly one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.0% of the 4,003 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on IAD to ATL?
Delta Air Lines leads at 79.9% on time across 2,233 flights. Frontier Airlines is at the other end on 68.0%, a gap of 12 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 ATL?
The 8am–11am departure window is the strongest at 86.4% on time. The 8pm–5am window is the weakest at 66.0%, 20 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 ATL?
July is the weakest month at 63.0% on time, compared with 88.2% in September. Across the year that is 25 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
- ATL to IAD — the return legseparate record
- Washington Dulles International (IAD) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Delta Air Lines on IAD to ATL79.9%
- United Airlines on IAD to ATL79.9%
- Frontier Airlines on IAD to ATL68.0%
- IAD to DEN, a related route83.1%
- LGA to ATL, a related route75.5%
- IAD to SFO, a related route77.5%
- Delta Air Lines on-time record79.9%
- United Airlines on-time record79.9%
- Republic Airways on-time record78.9%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. IAD to ATL and ATL 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.