American Airlines is doing a bit of housekeeping at Philadelphia International Airport (PHL). In an effort to reduce layover durations and eliminate the need for very early morning departures, the world’s largest airline is re-banking its flights at its fourth largest hub.

What does banking (or re-banking) flights mean? A bank of flights is essentially a wave of multiple flights that arrive ar an airport in a specified time frame. Currently, American Airlines (AA) has eight of these waves arriving to PHL on any given day. Beginning January 1, 2017, this number of waves will be reduced to six.

Why is AA making these changes? It will tighten the duration of many layovers for passengers transiting at PHL when flying on American. It will also help to do away with very early departures in the morning (5:00 AM departures out of PHL will now depart 90 minutes later, at 6:30 AM). The hope is that more favorable departure times will entice passengers to choose AA over its competition out of Philadelphia. And the final reason American is re-banking PHL? Because it’s worked before! PHL is the fourth hub to be re-banked since American merged with US Airways. Chicago, Dallas/Fort Worth, and Miami have already undergone successful re-banking efforts.