What does it mean when I hear a pilot say, for example, “decending to 2000 Sierra” What does the “Sierra” mean? I know it stands for “S”, but what does that indicate? I hear any range of phonetics.
Thanks.
Most likely the ATIS information they have.
It can be ATIS information or it is in this case the indicated waypoint Sierra where the aircraft has to be at 2000 ft.
In aviation the NATO phonetic spelling alphabet is used
This ensures that the spelling is done the same world wide and pronounced the same way.
Some deviations are present, the article on wikipedia is quite complete
1 Like
Waypoints are given a 5 letter, pronounceable name-code.
Most of the time that is a five letter designation yes.
Attached a VFR approach chart with 7, 6, 5 and 4 letter designators for reporting points as they officially are called. 
All in single ctr on 2 different arrival routes (mandatory reporting points are black triangles and non mandatory reporting points are white triangles)
1 Like