No, it's 12% of a much lower number. If I read you right, you are figuring b plan and 401k.
"The 401(a)(17) annual compensation limit applicable to retirement plans increased from $275,000 to $280,000."
So $33,600 from the company, $19,000 max from you towards the 56,000 limit. $3400 post tax if you want as a Capt. or make over $280,000.
The $5000 catch up over 50 doesn't affect these numbers