Not sure what you mean by "average" or how a static list harms one group but helps another when they both start out in the same relative slot. For this population a modal average means nothing and an arithmetic mean yields the same mid-point result as an median so we are talking about pilots who are right in the middle of the population. If the denominator remains static such that people who exit the list for whatever reason are replaced by someone with a lower number than they hold, then they either retain the same seniority they had (person exiting below their position so no gain) or they move up because the vacancy was created above them. Thus pilots with seniority numbers 2400 and 2401 by way of example either stay right where they are or they both move up to fill a vacancy. Neither pilot gains faster than the other. Both will stay at number 2400/2401 or they will both move up to 2401/2402 or whatever. This will remain the case until one or both of those pilots exits the list themselves at which point seniority becomes a non-issue for the terminated pilot unless they are going to harbor bad feelings for years post termination.
