Aircraft passed within a few feet of each other when a helicopter crew lost awareness which pilot had control of their aircraft and which had approaching aircraft traffic in sight.

Narrative

A VFR helicopter crew was checking all mission equipment for proper operation before overseas deployment. Pilot flying was in the starboard seat; Pilot not flying in port seat with head down energizing and programming gear. Were cleared to cross below the N to S ILS approach path from W to E and 'report traffic on final in sight'. Pilot flying asked pilot not flying; 'You got the aircraft'? Pilot not flying; lacking situational awareness; 'UHH; yeah' and took over flight controls. A Cessna 412 broke out of the overcast; could not see helicopter. Helicopter pilot took no evasive action. Cessna cleared top of helicopter by just a few feet. Starboard-seat pilot remarked; 'Wow that was close.' Port-seat pilot responded; 'What was close?' I was in the port seat. I never saw the Cessna. I thought the starboard-seat pilot wanted me to take control for some reason. He thought I saw the conflicting aircraft and would take evasive action. Lesson learned: 'I have control' and 'You have control' are MAGIC WORDS. Never say 'You got the aircraft?'