Flights more "on time" -- maybe

AP would have you believe today that airplane flights in the United States are more on-time of late.

Actually, while that's likely true to some extent, the article doesn't have the data to show it.

The article rightly points to good weather in the last year and fewer flights due to the slow economy. So it's indeed extremely likely that things are better than they were a few years ago.

But doing a comparison of the official "on time" statistics? That's meaningless, because the airlines change the amounts of time scheduled for given flights.

For example, you could have a flight that was once schedule for 60 minutes now be scheduled for 80 minutes. And the average time for arrival could move from being 75 minutes after scheduled departure to 80 minutes after scheduled departure. Yet your "on time arrival" rate would still go up. The AP article actually notes that scheduled flight times have changed.

AP and other outlets should not do historical comparisons of on-time arrival statistics. If they want to do a historical comparison with any meaning, they need to build their own database of how long flights used to take and how long they take now.