While reading an article about Hang Gliding reserve parachutes, I came across the acronym "PDA". The article seemed to imply that this is a type of parachute and a further google search seems to confirm that.
What I haven't been able to find is a source explaining what this acronym stands for. Wikipedia disambiguation offers no help and neither do several aviation glossaries I a familiar with. Lastly, a search for "PDA" in this forum provides no results.