While a PC pilot is in his battlemech, he is considered to have the ‘Toughness’ Advantage.
Toughness: The PC has a exceptional resistance to physical abuse. He makes Consciousness Rolls (both in personal combat and in Mech combat) with 3d6, using the best two. It might also help him withstand interrogation and such.
NPC and enemy Mech Pilots in battlemechs must make consciousness checks as do PC characters do to avoid passing out.