It used to be that no middle marker gave you a 50 foot penalty. That
went away back in the late eighties. If they still talk about that, they
need to remove that.

I hate to sound stupid, but what exactly is this 50' penalty for a middle
marker--either now or in the past?

Kobra





The outer marker is specifically required by regulation. You can
substitute another fix that happens to be in the same place. Our local
TERPS expert can get into the why, but there's no particularly strong
reason other than the regs say it is a component of an ILS.