Is experience not roughly defined as total hours?
If Pilot A has more hours than Pilot B, he's more experienced, right?
This measure being adjustable for other helpful ratings such as TRI, TRE etc, and to an extent by command hours.
With the argument further up the thread regarding pilots being required to do identical jobs with identical performance in mind, and thus given that there are no variables, surely experience (and therefore seniority) can be mathematically calculated by formula?
Something like (thumbsuck here)
Experience = TT + (PIC/3) + (TRE*1000)
results of formula then defining where in new airline applicant fits in. If it's DEC above existing FO, then FO accepts DEC is more experienced. If it's FO below more experienced FO's, applicant accepts the existing FO's are more experienced.
If applied globally, would be a fair system.