NAS
National Airspace System
NAV
Navigation receiver
NAVCOMM
Navigation and Communications equipment or receiver
NAVSTAR-GPS
The formal name for the space-borne or satellite navigation system
NCATT
National Center for Aircraft Technician Training
ND
Navigation Display
NDB
Non-Directional radio Beacon
NDB
Non-Directional Beacon
NFF
No Fault Found
NM or NMI
Nautical Mile
NPA
Non-Precision Approach
Navaid
Navigational Aid