| Acronym |
Definition |
| NBAA |
National Business Aircraft Association, USA. |
| NDB |
Non-Directional Beacon. A medium-frequency navigational aid which transmits non-directional signals, superimposed with a Morse code identifier and received by an aircraft's ADF. |
| NM |
Nautical Mile. |
| NOE |
Nap Of Earth. Low flying, usually by the military, using contour-flying techniques and terrain-masking to avoid being seen. |
| NORDO |
No Radio (used on flight plan form). |
| NOSIG |
No Significant Change, term used on Met reports. |
| Notam |
Notices to Airmen, issued by the CAA (and equivalent authorities elsewhere) to inform pilots of new or changed aeronautical facilities, services, procedures or hazards, temporary or permanent. |
| NOTAR |
No Tail Rotor. A system patented by McDonnell Douglas for maintaining directional control of helicopters without use of an anti-torque tail rotor. |
| NPRM |
Notice of Proposed Rule-Making (USA). |
| NTSB |
National Transportation Safety Board (U.S. equivalent of UK AAIB). |
