It's really to do more with the bonehead things we see on a regular basis. You mention the FOM. It seems some of you are not familiar with certain procedures in the FOM which can make some people like FFDO's very jumpy.
This is an incident recently reported
"Another Eastie story.
Flying today and we had an Eastie FO on the JS. Did a lav break and he went first. See the lav light go out and get up waiting for him to call to be let back in. Nope! the moron uses the key pad and we get the warning beeps. Captain calls back and 1st had no idea he used the pad as her back was turned. I let him in with a "we don't do that here" comment and go do my thing. When back up front _____ has been given him an ass chewing and he uses the excuse that he doesn't know how to work the phone intercom from the back, despite being on the bus. The rookie chick's enlightened him."
"The stories are true. This stuff is happening back there as they seem to think it is ok to make up their own procedures."
"I have had easties tell me the way we do the bathroom breaks is not how they do it in the east. That was totally unacceptable. Good job educating him."
"Same thing happened to me a few years back except the Capt. and I went first and used proper procedure to let back onto the flight deck, then the east hole went back and used the same procedure you just described, used the key pad to try to let him self in. They're nothing but a bunch of jerk off's pretending they're the most professional aviators in the business."
