Global and local shocks such as COVID-19 or the Russian attack on Ukraine have influenced European air transport, and other shocks will appear in the future. The subsequent traffic shifts affect one bottleneck candidate of the system: the Air Navigation Service Providers (ANSP). In this paper, we apply productivity metrics and Malmquist Data Envelopment Analysis to examine how the ANSP related performance of the air transport system has changed between 2008 and 2020. By considering different levels of granularity we demonstrate the tremendous influence that shocks may have on demand figures and, subsequently, on performance metrics. As an example we show that the Corona pandemic had disparate impacts on various units, resulting in notable efficiency losses in 2020, however, with a strong variation between ANSPs. The findings of our study can be utilized in a subsequent root-cause analysis to quantify the impacts of both endogenous and exogenous factors on performance. This in turn will provide valuable insights for policymakers and industry stakeholders in managing air transport during and after such shocks, and to create a more resilient air traffic management system.