copilot vs disembark

copilot

verb
  • To serve as relief or assistant pilot. 

noun
  • A backup or assistant pilot of an aircraft. 

disembark

verb
  • To go ashore out of a ship or boat; to leave a train or aircraft. 

  • To remove from on board a vessel; to put on shore 

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