firebomber vs pilot light

firebomber

noun
  • One who carries out a firebombing attack. 

pilot light

noun
  • A small, persistent flame used to ignite gas. 

  • A small telltale lamp on a dynamo or battery circuit whose brightness indicates the voltage of the current. 

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