Look in CFR 49 chapter XII. under flight deck privileges.
§*1544.237***Flight deck privileges.
(a) For each aircraft that has a door to the flight deck, each aircraft operator must restrict access to the flight deck as provided in its security program.
Every 121 carriers security program has to follow TSA mandates and guidelines. You won't find any specifics on what is included because as a 121 pilot you're not allowed to talk publicly about it. Trust me though, it's SOP to never allow a single pilot in a cockpit while an aircraft is in the air.
Aussie, everything changed after 9/11 as far as 121 security is concerned. I've just returned to Oz after 10 years of flying 121 in the US.
Last edited by Kenny; 28th Feb 2012 at 11:11.
Reason: Found the correct reference.