Section 171.301

14 CFR Ch. I (1-1-19 Edition)

keep the original of each form at the
facility and send a copy to the appropriate FAA Regional Office at the end
of each month in which it is prepared.
However, where an FAA approved remote monitoring system is installed
which precludes the need for periodic
maintenance visits to the facility,
monthly reports from the remote monitoring system control point must be
forwarded to the appropriate FAA Regional Office, and a hard copy retained
at the control point.
(c) Technical Performance Record (FAA
Form 418). FAA Form 418 contains a
record of system parameters, recorded
on each scheduled visit to the facility.
The owner or his maintenance representative shall keep the original of
each month-s record at the facility and
send a copy of the form to the appropriate FAA Regional Office.

Subpart J - Microwave Landing
System (MLS)
SOURCE: Docket No. 20669, 51 FR 33177,
Sept. 18, 1986, unless otherwise noted.

Section 171.301 Scope.
This subpart sets forth minimum requirements for the approval, installation, operation and maintenance of
non-Federal Microwave Landing System (MLS) facilities that provide the
basis for instrument flight rules (IFR)
and air traffic control procedures.
Section 171.303 Definitions.
As used in this subpart:
Auxiliary data means data transmitted in addition to basic data that
provide ground equipment siting information for use in refining airborne position calculations and other supplementary information.
Basic data means data transmitted by
the ground equipment that are associated directly with the operation of the
landing guidance system.
Beam center means the midpoint between the Section3 dB points on the leading
and trailing edges of the scanning
beam main lobe.
Beamwidth means the width of the
scanning beam main lobe measured at
the Section3 dB points and defined in angular units on the boresight, in the horizontal plane for the azimuth function

and in the vertical plane for the elevation function.
Clearance guidance sector means the
volume of airspace, inside the coverage
sector, within which the azimuth guidance information provided is not proportional to the angular displacement
of the aircraft, but is a constant flyleft or fly-right indication of the direction relative to the approach course
the aircraft should proceed in order to
enter the proportional guidance sector.
Control Motion Noise (CMN) means
those fluctuations in the guidance
which affect aircraft attitude, control
surface motion, column motion, and
wheel motion. Control motion noise is
evaluated by filtering the flight error
record with a band-pass filter which
has corner frequencies at 0.3 radian/sec
and 10 radians/sec for azimuth data and
0.5 radian/sec and 10 radians/sec for elevation data.
Data rate means the average number
of times per second that transmissions
occur for a given function.
Differential Phase Shift Keying (DPSK)
means differential phase modulation of
the radio frequency carrier with relative phase states of 0 degree or 180 degrees.
Failure means the inability of an
item to perform within previously
specified limits.
Guard time means an unused period of
time provided in the transmitted signal
format to allow for equipment tolerances.
Integrity means that quality which
relates to the trust which can be placed
in the correctness of the information
supplied by the facility.
Mean corrective time means the average time required to correct an equipment failure over a given period, after
a service technician reaches the facility.
Mean course error means the mean
value of the azimuth error along a
specified radial of the azimuth function.
Mean glide path error means the mean
value of the elevation error along a
specified glidepath of the elevation
function.
Mean-time-between-failures
(MTBF)
means the average time between equipment failures over a given period.

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