The average flight today from Kennedy Airport to LAX is slower than it was in 1995 in every conceivable way. Planes face longer delays leaving the gate; take more time taxiing before taking off; and spend more time in the air.

But paradoxically, even with an average rise in travel time of 18 minutes, the percentage of flights on this route arriving after the scheduled arrival time has decreased. In 1995, the arrivals were behind schedule 51 percent of the time; today it’s just 37 percent.

Why do today’s flights arrive early more often, even though they’re slower? Airlines have extended their scheduled flight durations even more than the flights have lengthened in actual duration. The average scheduled duration from J.F.K. to Los Angeles has increased 23 minutes since 1995, according to an Upshot analysis of Bureau of Transportation Statistics data.

Thanks to those more forgiving schedules, a majority of domestic flights nationwide arrive early or on time. If your plane reaches the gate at exactly the estimated arrival time, you are actually on a plane that is running slower than usual.