You basically have two choices. You can wait until the older craft are replaced in your squadron, or you can use the "ME" java mod to allocate your pilot a new aircraft.
"ME" has a lot of capabilities so it would be worthwhile to read through the "ReadMe" file that accompanies it. There are lots of inherent goodies in that mod.
Question about this having been a “victim” of what the OP describes.
Since mission results are saved to your career (some of it anyway) do you have to do the plane switch every mission or is the changed aircraft saved to your career via mission results and now permanent?