in transit vs on board

in transit

prep
  • In the process of being transported. 

on board

adv
  • Agreeing or supporting; having been taken on board. 

  • On a vehicle or vessel; aboard. 

adj
  • On or in a means of transportation. 

  • Agreeing or supporting. 

  • Joining in or participating. 

  • Into itself or oneself. 

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