Schedule padding effects following airport slot reforms: A synthetic difference-in-differences procedure

The regulatory change in takeoffs and landings at Newark Liberty Airport offers a unique opportunity to examine the impacts of a potentially exogenous shock on airline schedule padding practices. In 2016, the Federal Aviation Administration reclassified Newark from a Level 3 to a Level 2 airport, signifying a less restrictive operational environment. Using a Synthetic Difference-in-Differences (SDID) methodology, we compare Newark flights with a synthetic control group of flights from other airports, isolating the effect of the slot control removal on schedule padding. We find that the regulatory change led to a reduction in schedule padding, particularly for flights arriving at Newark, where the reduction ranged from 2.35 to 2.85 min. This reduction is considerable, especially when considered in the context of the average schedule padding of 7.5 min, representing a 31–38 % decrease in padding for Newark-related flights. • Newark’s 2016 slot removal enables analysis of airline schedule padding after a policy-driven shock. • This study uses SDID to estimate slot deregulation effects by comparing Newark flights to a synthetic group. • The policy cut padding by 2.35–2.85 minutes—a 31–38% drop from Newark’s pre-policy 7.5-minute average. • Reducing slot limits boosts scheduling efficiency and guides congestion and regulatory policy at busy airports.