Originally Posted by LarryJ

That's not how it works. Rules for cockpit access will be those of the country under which the airline's operating authority is issued. It does not change based on the destination or the airspace through which the flight flies.

Countries can add most restrictive rules for airliners operating in their airspace but that is the exception, not the norm. The UK, I believe, is one country that has such a rule.

US airline cockpit access was locked down well before I started in the industry in 1990 and was tightened further after 9/11. Many non-US countries tightened their cockpit access rules after 9/11 as well. I have no specific knowledge of the current rules for non-US airlines so can't add anything to what requirements may be for TAP.