I will admit that I am not a pilot, so forgive me if the following question is a simple one.
I know that there many different kinds of approaches (such as ILS approach, RNAV approach, NDB approach, VOR/DME approach, and visual approach). I'm still trying to learn the differences between these types of approaches. But what I'd like to focus on is the "RNAV Approach".
I understand that RNAV stands for "aRea NAVigation". When a terminal controller that manages aircraft arrivals to the airport, he/she will say to the pilot "you are cleared for the RNAV (insert runway #) approach".
Recently in Ottawa (CYOW), I have heard ATC tell pilots that they are cleared for the "RNAV Z" or "RNAV Y" approach (RNAV Zulu and RNAV Yankee, respectively).
The question is: what is the difference between an RNAV Z/RNAV Y approach versus an actual RNAV approach?