---
kind: "section"
citation: "14 C.F.R. § 171.21"
title: "14"
number: "171.21"
heading: "Scope."
url: "https://uscodex.org/cfr/14/171.21"
---

# §171.21. Scope.

- (a) This subpart sets forth minimum requirements for the approval and operation of non-Federal, nondirectional radio beacon facilities that are to be involved in the approval of instrument flight rules and air traffic control procedures related to those facilities.
- (b) **A nondirectional radio beacon (“H” facilities domestically—** NDB facilities internationally) radiates a continuous carrier of approximately equal intensity at all azimuths. The carrier is modulated at 1020 cycles per second for station identification purposes.

## Notes

### Amendments

[Docket 5034, 29 FR 11337, Aug. 6, 1964, as amended by Amdt. 171-2, 31 FR 5408, Apr. 6, 1966; Amdt. 171-7, 35 FR 12711, Aug. 11, 1970]

### Authority

Authority: 49 U.S.C. 106(g), 40103-40107, 40109, 40113, 44502, 44701-44702, 44708-44709, 44711, 44719-44721, 45303, 46308.

### Source

Source: Docket 5034, 29 FR 11337, Aug. 6, 1964, unless otherwise noted.

### Amendments

[Docket 5034, 29 FR 11337, Aug. 6, 1964, as amended by Amdt. 171-2, 31 FR 5408, Apr. 6, 1966; Amdt. 171-7, 35 FR 12711, Aug. 11, 1970]