A PDRA, or Predefined Risk Assessment, is a ready-made EASA risk-assessment template for common specific-category operations. EASA has already analysed the typical scenario and written down the risks and their mitigations — PDRA-S01 is one example of such a template.
In practice this means an operator whose planned operation matches a PDRA can apply for an authorisation with a simplified dossier, instead of performing a full SORA assessment from scratch. That saves time for both the operator and the authority while keeping the same level of safety.