An open letter to Bozeman Tower/Serco
From email of 29 June 2007
To: KBZN Tower Manager
Greetings —
There is a recurring event with Computer Navigation Fixes (CNFs) which is incorrect procedure and establishing bad habits amongst area pilots.
CNFs exist for the purpose of database management and can be identified by the name being enclosed by parentheses. For example, on BZN’s VOR/DME or GPS 12 approach, several CNFs are published: (NUHRE), (CFKSH), (EHUTU), and (MADSE).
Tower and pilots have been incorrectly referring to these CNFs by trying to pronounce the enclosed name, such as “…report EHUTU….,” rather than the standard phraseology, “…report 6 DME…” or “…report FAF….”.
Per AIM 1-1-19 j. Waypoints,
2. …. A point used for the purpose of defining the navigation track for an airborne computer system (i.e., GPS or FMS) is called a Computer Navigation Fix (CNF). CNFs include unnamed DME fixes, beginning and ending points of DME arcs and sensor final approach fixes (FAFs) on some GPS overlay approaches. To aid in the approach chart/database correlation process, the FAA has begun a program to assign five-letter names to CNFs and to chart CNFs on various National Oceanic Service aeronautical products. These CNFs are not to be used for any air traffic control (ATC) application, such as holding for which the fix has not already been assessed. CNFs will be charted to distinguish them from conventional reporting points, fixes, intersections, and waypoints. The CNF name will be enclosed in parenthesis, e.g., (MABEE), and the name will be placed next to the CNF it defines. If the CNF is not at an existing point defined by means such as crossing radials or radial/DME, the point will be indicated by an “X.” The CNF name will not be used in filing a flight plan or in aircraft/ATC communications. Use current phraseology, e.g., facility name, radial, distance, to describe these fixes.
This has been an ongoing point of discussion amongst clients and visitors. It dawned on me that you might not have been made aware of the problem.