Originally Posted by
PanAmWT
This was happening today. He was No.4 in a waitlist without instrument (a CPU flight). When I applied my +P, he dropped to No.6. I removed my +P, he is now back to No. 4 again.
Is this because a GS without instrument is ahead of others who use instruments, including those sponsored by GS points or miles. But when a GS using instruments from another GS, the rank dropped because the passenger GS now falls into the category of being sponsored by a (different) GS..
My guess is that "supported by a GS instrument" and "GS CPU" have identical priority as they are WLPA waitlisted for PN. Adding the Plus Points reset the time of request and Numbers 5 and 6 are GS with a same fare class who bought their tickets later.
Just a guess though - it does require a rather improbably set of circumstances.