All the discussion about 'seniority vs meritocracy' seems to revolve entirely around command upgrades. It appears very much that those getting their upgrades under the 'seniority' systems have to jump just as many grading and qualification hurdles (i.e. they need to merit their upgrade) as those in 'meritocracy' systems. So all the 'brown nosing' and unfair grading complaints that have been made are equally as possible under each system (you can be held back from an upgrade when your turn comes up under a seniority system by the same unfairness). So if you are concerned about unfair treatment then it is a risk under both systems.
But seniority based systems do not only regulate command upgrades, they strangle all sorts of other movement in airlines, such as base or fleet transfers, leave allocation, etc., etc.
Why is it right that if for example pilot A wants to transfer to XYZ fleet or base and has had an application in for it for over a year, yet two weeks before the vacancy that he/she has wanted becomes available, pilot B suddenly decides that he/she would like that fleet or base transfer and 'trumps' pilot A (who has really wanted that transfer for quite some time) solely because of their positions on a seniority list.
Likewise, why is it right that first officer C who is very well qualified and passes all the command criteria with very, very good marks but can't get an upgrade because things are moving a little slowly in that airline and has waited over a year since 'ticking all the boxes', then just as that much awaited command is almost there, first officer D who had joined with low hours and has just barely scraped through all the grades required finally manages the bare minimum hours for upgrade and 'trumps' first officer C solely because of their places on a seniority list.
Wouldn't a 'first-come-first-served' system be much fairer?
When pilot A puts in an application for that transfer to XYX fleet or base he/she goes on a waiting list. If pilot B decides a year later that he/she would like that same transfer he/she goes on that list behind everyone else who had already made their applications. When that vacancy becomes available then the pilot who applied first gets it first.
When first officer C 'ticks all the boxes' for a command upgrade, he/she goes on a waiting list and anyone who subsequently 'ticks the required boxes', such as first officer D (above), goes on that waiting list after first officer C. When a command vacancy is available first officer C, who has been qualified and waiting longest, gets that first opportunity.
(I cannot think of any other industry where a lower qualified person, like first officer D above with is 'only just good enough' grades and only just attained flying hours, gets promotion ahead of someone who is more able and better qualified simply because of their positions on some list.)
Why should a very competent and experienced captain whose airline has gone bust (due to something way out of his control, such as terrorist activity) be condemned to having to work as a first officer for the next decade or so simply because he is at the bottom of any seniority list in any other airline that he joins and is behind that cadet fresh out of flying school who joined the week before?
Seniority systems are simply a 'tyranny of the senior' and a tool of management to keep Ts & Cs down as pilots will be reluctant to leave to go elsewhere for a potentially better deal because they'll loose their precious place on that list (and possibly need to start on the bottom of someone else's list). It is amazing that such a modern industry (public air transport hasn't been around for a full century yet) is bedevilled by such archaic workplace practices.
And this is not a new problem: if you read Ernest K Gann's "Fate is the Hunter", which was first published closer to Bleriot's crossing of the Channel than to today, he refers to positions on a seniority list as "Those miserable numbers!".
The industry needs to be modernised and get rid of seniority lists. Fortunately it appears that some airlines are doing so.