open source information; FAM/FFDO program standards....
I can't speak for every post or topic related data listed here but the information I brought up is mostly from open sources & the media.
I can see how or why firearms qualifications are strict for FAMs or Flight Deck Officers. Being trained in the use of non-lethal weapons like EDWs(Tasers), OC spray & ASPs/PR24s may help a lot too.
A more common problem seems to be intoxicated or unstable airline passengers.
I do not travel by aircraft often but I was looking at the 2011 Safariland product catalog and put some thought to carrying a few compact zip-ties or "Flexi-cuffs"(the US Army term) if allowed by TSA/FAA regs. These strong, plastic ties could detain a subject(s) until the plane could land safely.
These safety & counter-terrorist issues are no joke. My sister's good friend worked as a flight attendant based in LA for Alaska Airlnes. He had to leave the airline position due to stress & mental health reasons. He said he worked on 2 different flights that had documented incidents of "suspicious" actions & possible terrorist activity. His fear & anxiety finally became to much.