A route assigned to pilots when any part of an airway or route is unusable because of NAVAID status. These routes consist of:
- Substitute routes which are shown on U.S. Government charts.
- Routes defined by ATC as specific NAVAID radials or courses.
- Routes defined by ATC as direct to or between NAVAIDs.
Source FAA Pilot/Controller Glossary · checked 2026-08-25