What does the acronym PDA stand for in the aviation domain 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.
Pull-down apex. It's an additional attachment point in the center of the parachute. Putting force on it makes the parachute open up more like a half-donut, rather than a half-sphere. That provides more effective area for an annular parachute. That hole in the middle is needed for stability.



Link: one product of this type with a bit of explanation.