Legacy airlines? Seniority systems? Why does that imply better Ts&Cs?
Swissair was a 'legacy' airline with a seniority system (could someone confirm that last bit?). I wonder what their Ts&Cs were like on 1 April 2002?
Don't take anything for granted in this industry. Many, many, many top airlines are now 'has beens' with absolutely no Ts&Cs for their plots.
"What other systems are in use that do not use seniority?"
A first-come-first-served system.
If you bid for something and someone else bids for it a month (or even an hour) later, you are first and they are second. Once someone meets all the criteria for something (say a command) then they are on the list and someone who meets those criteria a month later, they are second on that list.
Let me give you some examples:
Pilot B is a junior pilot but is really keen on a base move, so he bids for it. It takes a year for a vacancy to come up and just before it does so Pilot A, who is an old timer in the company, decides to bid for that base. On the first-come-first-served system, Pilot B gets the base move. However, on a seniority system, Pilot A (who had absolutely no interest in that other base for all of the last year) can play his last-minute trump card of seniority and get that base that Pilot B had been longing for for the past year. Which one is fair?
Pilot B is very experienced and had a command (on the same aeroplane) in his previous airline but could only get a position as an FO in this airline; he meets every single criteria for a command but command vacancies are still a long way off. However, Pilot A is a newby straight out of flying school (and with a long career still ahead of him) is still a long way short of the hours for a command but meets all the other criteria. As a command becomes available, Pilot A just 'sneaks' over the barrier on the hours required. In the seniority system Pilot A has the trump card of seniority to take that vacancy In the first-come-first-served system Pilot B, with vastly more experience but has had to wait for ages, gets the command. Which one is fair?
I have seen exactly that base move 'seniority trump card' used in a previous airline. Everyone thought it was unfair.