Student or Learner
' The missions are too contrived and you don't receive enough information to successfully carry out a mission. For example, one desert objective is to "fly around and home in on a radio signal" but there's no real way to gauge where the signal is coming from and you'll end up just flying around in a sandstorm and happening upon the enemy camps by luck alone.'
To happen upon is a set phrase and means to find unexpectedly.
happen upon - definition of happen upon by the Free Online Dictionary, Thesaurus and Encyclopedia.