From Elsmar Cove Quality Assurance and Business Standards Wiki
Layered Process Audit - A Layered Process Audit (both DCX and GM/Delphi have used them) is a check by 'layers' of management to see if work instructions are being followed (mainly since DCX, the loudest proponent of LPA's) don't utilize Control Plans as their suppliers do. The focus is getting 'issues' escalated to higher management to get them resolved.
Also see Process Audit
Elsmar Cove Forum Layered Process Audit discussion threads.