Question: I am an instrument pilot in training at an airport that has two RNAV approaches for the same runway. One is labeled RNAV (GPS) Y RWY 16; the other is RNAV (GPS) Z 16. Why would the FAA create two GPS approaches to the same runway?
Answer: Broadly speaking, the Y approach is more geared toward single-engine, piston-powered aircraft, and the Z approach more appropriate for jets.
Put the approach plates side by side and you’ll note the Z has lower weather minimums than the Y. They may also require different aircraft equipment and pilot certification, step-down fixes, and altitudes. The devil can be in the details, as a side-by-side comparison may reveal different missed approach instructions and one with a virtual glideslope that is not coincident with the RNAV glide path. One may allow circling, while the other does not.
When requesting an approach at an airport with both the Z and Y variant, make sure you ask for the one most appropriate for your aircraft and pilot qualifications. If you (or your aircraft) don’t meet the approach criteria, be sure to tell ATC “unable.”