title-14-part-171-sec171-271

848

14 CFR Ch. I (1–1–24 Edition)

§ 171.267

achieved at an angle not less than 0.30

above the horizontal. However, if it is
achieved at an angle above 0.45

, the

DDM value may not be less than 0.22 at
least down to an angle of 0.45

[Doc. No. 14120, 40 FR 36110, Aug. 19, 1975; 40
FR 41093, Sept. 5, 1975; 40 FR 43719, Sept. 23,
1975]

§ 171.267 Glide path automatic mon-

itor system.

(a) The ISMLS glide path equipment

must provide an automatic monitor
system that transmits a warning to
designated local and remote control
points when any of the following oc-
curs:

(1) A shift of the mean ISMLS glide

path angle equivalent to more than
0.075

(2) For glide paths in which the basic

functions are provided by the use of a
single frequency system, a reduction of
power output to less than 50 percent.

(3) A change of the angle between the

glide path and the line below the glide
path (150 Hz predominating), at which a
DDM of 0.0875 is realized by more than

0.0375

(4) Lowering of the line beneath the

ISMLS glide path at which a DDM of
0.0875 is realized to less than 0.75

from

the horizontal.

(5) Failure of any part of the monitor

itself. Such failure must automatically
produce the same results as the mal-
functioning of the element being mon-
itored.

(b) At glide path facilities where the

selected nominal angular displacement
sensitivity corresponds to an angle
below the ISMLS glide path, which is
close to or at the maximum limits
specified, an adjustment to the mon-
itor operating limits may be made to
protect against sector deviations below
0.75

from the horizontal.

rence of any of the conditions pre-
scribed in paragraph (a) of this section,
including periods of zero radiation,
glide path signal radiation must cease.

§ 171.269 Marker beacon performance

requirements.

ISMLS marker beacon equipment

must meet the performance require-
ments prescribed in subpart H of this
part.

§ 171.271 Installation requirements.

(a) The ISMLS facility must be per-

manent in nature, located, con-
structed, and installed according to ac-
cepted good engineering practices, ap-
plicable electric and safety codes, FCC
licensing requirements, and paragraphs
(a) and (c) of § 171.261.

(b) The ISMLS facility must have a

reliable source of suitable primary
power, either from a power distribution
system or locally generated. Adequate
power capacity must be provided for
the operation of test and working
equipment of the ISMLS.

continuously engaged or floating bat-
tery power source for the ground sta-
tion for continued normal operation if
the primary power fails. A trickle
charge must be supplied to recharge
the batteries during the period of avail-
able primary power. Upon loss and sub-
sequent restoration of power, the bat-
teries must be restored to full charge
within 24 hours. When primary power is
applied, the state of the battery charge
may not affect the operation of the
ISMLS ground station. The battery
must permit continuation of normal
operation for at least two hours under
the normal operating conditions. The
equipment must meet all specification
requirements with or without batteries
installed.

(d) There must be a means for deter-

mining, from the ground, the perform-
ance of the equipment including anten-
nae, both initially and periodically.

(e) The facility must have, or be sup-

plemented by, ground-air or landline
communications services. At facilities
within or immediately adjacent to con-
trolled airspace and that are intended
for use as instrument approach aids for
an airport, there must be ground-air
communications or reliable commu-
nications (at least a landline tele-
phone) from the airport to the nearest
Federal Aviation Administration air
traffic control or communication facil-
ity. Compliance with this paragraph
need not be shown at airports where an
adjacent Federal Aviation Administra-
tion facility can communicate with
aircraft on the ground at the airport
and during the entire proposed instru-
ment approach procedure. In addition,
at low traffic density airports within

849

Federal Aviation Administration, DOT

§ 171.273

or immediately adjacent to controlled
airspace, and where extensive delays
are not a factor, the requirements of
this paragraph may be reduced to reli-
able communications (at least a
landline telephone) from the airport to
the nearest Federal Aviation Adminis-
tration air traffic control or commu-
nications facility, if an adjacent Fed-
eral Aviation Administration facility
can communicate with aircraft during
the proposed instrument approach pro-
cedure, at least down to the minimum
en route altitude for the controlled
area.

(f) Except where no operationally

harmful interference will result, at lo-
cations where two separate ISMLS fa-
cilities serve opposite ends of a single
runway, an interlock must ensure that
only the facility serving the approach
direction in use can radiate.

[Doc. No. 14120, 40 FR 36110, Aug. 19, 1975, as
amended by Amdt. 171–16, 56 FR 65665, Dec.
17, 1991]

§ 171.273 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
needed to maintain the facility, includ-
ing proficiency in maintenance proce-
dures and the use of specialized test
equipment.

(b) In the event of out-of-tolerance

conditions or malfunctions, as evi-
denced by receiving two successive
pilot reports, the owner must close the
facility be ceasing radiation, and issue
a ‘‘Notice to Airman’’ (NOTAM) that
the facility is out of service.

tain approval of, an operations and
maintenance manual that sets forth
mandatory procedures for operations,
periodic maintenance, and emergency
maintenance, including instructions on
each of the following:

(1) Physical security of the facility.
(2) Maintenance and operations by

authorized persons.

(3) FCC licensing requirements for

operations and maintenance personnel.

(4) Posting of licenses and signs.
(5) Relation between the facility and

FAA air traffic control facilities, with
a description of the boundaries of con-
trolled airspace over or near the facil-
ity, instructions for relaying air traffic
control instructions and information,
if applicable, and instructions for the
operation of an air traffic advisory
service if the facility is located outside
of controlled airspace.

(6) Notice to the Administrator of

any suspension of service.

(7) Detailed and specific maintenance

procedures and servicing guides stating
the frequency of servicing.

(8) Air-ground communications, if

provided, expressly written or incor-
porating appropriate sections of FAA
manuals by reference.

(9) Keeping of station logs and other

technical reports, and the submission
of reports required by § 171.275.

(10) Monitoring of the ISMLS facil-

ity.

(11) Inspections by United States per-

sonnel.

(12) Names, addresses, and telephone

numbers of persons to be notified in an
emergency.

(13) Shutdowns for periodic mainte-

nance and issue of ‘‘Notices to Airmen’’
for routine or emergency shutdowns.

(14) Commissioning of the ISMLS fa-

cility.

(15) An acceptable procedure for

amending or revising the manual.

(16) An explanation of the kinds of

activities (such as construction or
grading) in the vicinity of the ISMLS
facility that may require shutdown or
recertification of the ISMLS facility
by FAA flight check.

(17) Procedures for conducting a

ground check of the localizer course
alignment, width, and clearance, glide
path elevation angle and course width,
and marker beacon power, and modula-
tion.

(18) The following information con-

cerning the ISMLS facility:

(i) Facility component locations with

respect to airport layout, instrument
runways, and similar areas.

(ii) The type, make, and model of the

basic radio equipment that provides
the service.