Formal attire and one part formal interview. Engineering manager was easy-going so it was rather easy to transition to a less-formal discussion. Questions ranged from expertise in engineering to overall likes and dislikes. Manager was trying to get a feel for my overall outlook on life, not just if I was knowledgeable in the subjects necessary for the position (It was in Navigation Department of Flight Design and Dynamics Division of Mission Operations Directorate for Shuttle Operations).