TK MAXX-421 said:
I wonder how many Rebel pilots followed Biggs’ plan of attending the imperial academy and then defecting to the alliance? Sounds like Luke was planning on doing the same, is it a common? Surely the empire had measures in place to mitigate this?
Based on the dialogue of that scene, the academy is in some ways a separate entity from the actual Imperial army, given Biggs says that one becomes eligible for being drafted after completing the academy course.
The radio drama also has Biggs saying that a friend of his from the academy was suspected for Rebel sympathies and died in interrogation. Sounds like at least in Legends they made mention of some pretty severe measures in place to curb desertion, although our known canon defectors (Hobbie, Biggs, Wedge, and Bodhi) also seem to have had a tough time.