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817 

Federal Aviation Administration, DOT 

§ 171.11 

(c) The monitor is checked periodi- 

cally, during the in-service test evalua-
tion period, for calibration and sta-
bility The tests are made with a stand-
ard ‘‘Reference and variable phase sig-
nal generator’’ and associated test 
equipment, including an oscilloscope 
and portable field detector. In general, 
the ground check is conducted in 
accord- ance with section 8.4 of FAA 
Handbook AF P 6790.9 ‘‘Maintenance 
Instruction for VHF Omniranges’’, 
adapted for the facility concerned. 

(d) Flight tests to determine the fa-

cility’s adequacy for operational re-
quirements and compliance with appli-
cable ‘‘Standards and Recommended 
Practices’’ are conducted in accordance 
with the ‘‘U.S. Standard Flight Inspec-
tion Manual’’, particularly section 201. 

(e) After January 1, 1975, the owner of 

the VOR shall modify the facility to 
perform in accordance with paragraph 
3.3.5.7 of Annex 10 to the Convention on 
International Civil Aviation within 180 
days after receipt of notice from the 
Administrator that 50 kHz channel 
spacing is to be implemented in the 
area and that a requirement exists for 
suppression of 9960 Hz subcarrier 
harmonics. 

[Doc. No. 5034, 29 FR 11337, Aug. 6, 1964, as 
amended by Amdt. 171–7, 35 FR 12711, Aug. 11, 
1970; Amdt. 171–9, 38 FR 28557, Oct. 15, 1973] 

§ 171.9 Installation requirements. 

(a) The facility must be installed ac-

cording to accepted good engineering 
practices, applicable electric and safe-
ty codes, and the installation must 
meet at least the Federal Communica-
tion Commission’s licensing require-
ments. 

(b) The facility must have a reliable 

source of suitable primary power, ei-
ther from a power distribution system 
or locally generated, with a supple-
mental standby system, if needed. 

(c) Dual transmitting equipment 

with automatic changeover is preferred 
and may be required to support certain 
IFR procedures. 

(d) There must be a means for deter-

mining, from the ground, the perform-
ance of the equipment, including the 
antenna, initially and periodically. 

(e) A facility intended for use as an 

instrument approach aid for an airport 
must have or be supplemented by (de-

pending on circumstances) the fol-
lowing ground-air or landline commu-
nications services: 

(1) At facilities outside of and not im-

mediately adjacent to controlled air-
space, there must be ground-air com-
munications from the airport served by 
the facility. Separate communications 
channels are acceptable. 

(2) At facilities within or imme-

diately adjacent to controlled airspace, 
there must be the ground-air commu-
nications required by paragraph (e)(1) 
of this section and reliable communica-
tions (at least a landline telephone) 
from the airport to the nearest FAA 
air traffic control or communication 
facility. 

Paragraphs (e) (1) and (2) of this sec-
tion are not mandatory at airports 
where an adjacent FAA facility can 
communicate with aircraft on the 
ground at the airport and during the 
entire proposed instrument approach 
procedure. In addition, at low traffic 
density airports within or immediately 
adjacent to controlled airspace and 
where extensive delays are not a fac-
tor, the requirements of paragraphs (e) 
(1) and (2) of this section may be re-
duced to reliable communications (at 
least a landline telephone) from the 
airport to the nearest FAA air traffic 
control or communication facility, if 
an adjacent FAA facility can commu-
nicate with aircraft during the pro-
posed instrument approach procedure, 
at least down to the minimum en route 
altitude for the controlled airspace 
area. 

[Doc. No. 5034, 29 FR 11337, Aug. 6, 1964, as 
amended by Amdt. 171–7, 35 FR 12711, Aug. 11, 
1970; Amdt. 171–16, 56 FR 65664, Dec. 17, 1991] 

§ 171.11 Maintenance and operations 

requirements. 

(a) The owner of the facility must es-

tablish an adequate maintenance sys-
tem and provide qualified maintenance 
personnel to maintain the facility at 
the level attained at the time it was 
commissioned. Each person who main-
tains a facility must meet at least the 
Federal Communications Commission’s 
licensing requirements and show that 
he has the special knowledge and skills