DLATL→IAD

Delta flew 2,219 of the 3,979 flights on ATL to IAD, most of the route. Its 77.8% on time is about level with the route as a whole at 76.5%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Republic at 85.7% to Frontier at 63.0%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. United Airlines arrives on time 81.4% of the time; Frontier Airlines manages 63.0%. Sample sizes sit next to every figure, because a two-point gap across 640 flights means less than a ten-point one.

8.2% 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.

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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg is a different operation and performs like one: it runs 81.0% on time across 2,219 flights, 3 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 3 points of difference.

The sample behind these figures is 2,219 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.