3/3/3 is crap though that doesn't mean 6/4/7/4 is any better!!
6=3days + 3nights / 4 days off / 7= 3days +4nights / 4 days off
Those 4 days off aren't real off days since you finish at 0300hrs in the morning of day 1 and then you start again at 0900hrs on day 5.....in this short space of time you are trying to readjust your circadian rhythm only to throw it out again shortly there after.
The CAA was asked about the fact how healthy it is to interfere with one's circadian rhythm every three days......the answer was there haven't been no issues so far therefore carry on.
The old roster was fab instead of changing ones circadian rhythm every three days almost one changed it every 2 weeks, more healthier I would have thought???
I know for one thing a 747 captain wouldn't be allowed to work the NPAS roster that's for sure.