So what are the arguments? The two largest pilot's unions, the Air Line Pilots Association (ALPA) and the Allied Pilots Association (APA), endorse the regulation as it stands. They cite medical reasons, or more specifically, the aging process. It is hard to dispute the fact that as we grow older so do our body parts. The major issue for airline pilots is our cardiac system. There seems to be no precise medical test to predict its functionality, but the odds of it deteriorating increase as we approach age 60. There seems to be no precise medical test to predict the functionality of other biological systems, either. There are just too many variables. Testing for cognitive functions is equally complicated. ALPA & APA agree that the FAA has supported an arbitrary number, but if it's not broke, why try to fix it?