Plain English Meaning

When the same airport runway has more than one instrument approach of the same kind (say, two ILS approaches to the same runway), each one is given a different letter at the end of its name so pilots and controllers can tell them apart.

Full Definition

A naming convention used when more than one instrument approach procedure of the same type serves a single runway end. To distinguish them on charts and in clearances, each procedure is identified by a letter suffix in alphabetical order from the end of the alphabet backward — for example, ILS Z RWY 13L, ILS Y RWY 13L, ILS X RWY 13L. The suffix letter has no operational meaning; it is only a label that keeps the procedures from being confused with one another.

Context Anchor

Seen on instrument approach chart titles, such as RNAV () Z RWY 27 and RNAV (GPS) Y RWY 27.