Master and Weapon Arm should both be up, correct?
If I'm not mistaken Weapon Arm is only for Jettison.
So, no -- Master Arm UP - weapon arm Down.
(If I'm wrong I'm sure one of the vets will correct me.)
I turn it on as a leave the base, along with flicking on master arm and setting up my CM program.
Don't you lose a lot of info from the HUD when you activate Master Arm? Do you just fly by the analog instruments?
Edit: Never mind -- I was mistaken there, Master Arm doesn't change the HUD - I must have been thinking of uncageing the Shkval.