Current air user requirements in meters

Phase

Catagory

Position

Height

En route

>= 100

>= 100

Approach

I

17.1

4.1

And

II

5.2

1.7

landing

III

4.0

0.6

Referrences:
[1] B. Hofmann-Wellenhof, H. Lichtenegger, and J. Collins « GPS – Theory and Practice« , Third, revised edition, 1994, Spring-Verlag Wien New York