PLB vs airbridge

PLB

airbridge

noun
  • Synonym of jet bridge: an elevated corridor connecting an airport to a plane. 

  • A conductor on an integrated circuit that crosses over other conductors with an air gap introduced between in the wafer manufacturing process. 

  • The route and aircraft used to deliver material by an airlift. 

How often have the words PLB and airbridge occurred in a corpus of books? (source: Google Ngram Viewer )