Airlines are getting better at delivering passengers to their destinations on time - an encouraging trend for travelers hoping for disruption-free holiday flights. But at least some of that improvement is attributable to a bookkeeping trick that adds extra minutes to published flight schedules to provide a cushion for an on-time-arrival, experts say.

The Department of Transportation's latest report on air travel on Monday shows that the 13 reporting U.S. air carriers posted an overall on-time arrival rate of 87.0 percent in October, up from both the 80.0 percent on-time rate in October 2014 and an 86.5 percent rate in September of this year.