851
Federal Aviation Administration, DOT
§ 171.303
keep the original of each form at the
facility and send a copy to the appro-
priate FAA Regional Office at the end
of each month in which it is prepared.
However, where an FAA approved re-
mote monitoring system is installed
which precludes the need for periodic
maintenance visits to the facility,
monthly reports from the remote mon-
itoring system control point must be
forwarded to the appropriate FAA Re-
gional 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 rep-
resentative shall keep the original of
each month’s record at the facility and
send a copy of the form to the appro-
priate FAA Regional Office.
Subpart J—Microwave Landing
System (MLS)
S
OURCE
: Docket No. 20669, 51 FR 33177,
Sept. 18, 1986, unless otherwise noted.
§ 171.301 Scope.
This subpart sets forth minimum re-
quirements for the approval, installa-
tion, operation and maintenance of
non-Federal Microwave Landing Sys-
tem (MLS) facilities that provide the
basis for instrument flight rules (IFR)
and air traffic control procedures.
§ 171.303 Definitions.
As used in this subpart:
Auxiliary data
means data trans-
mitted in addition to basic data that
provide ground equipment siting infor-
mation for use in refining airborne po-
sition calculations and other supple-
mentary information.
Basic data
means data transmitted by
the ground equipment that are associ-
ated directly with the operation of the
landing guidance system.
Beam center
means the midpoint be-
tween the
¥
3 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
¥
3 dB points and defined in angu-
lar units on the boresight, in the hori-
zontal plane for the azimuth function
and in the vertical plane for the ele-
vation function.
Clearance guidance sector
means the
volume of airspace, inside the coverage
sector, within which the azimuth guid-
ance information provided is not pro-
portional to the angular displacement
of the aircraft, but is a constant fly-
left or fly-right indication of the direc-
tion 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 ele-
vation 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 rel-
ative phase states of 0 degree or 180 de-
grees.
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 toler-
ances.
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 aver-
age time required to correct an equip-
ment failure over a given period, after
a service technician reaches the facil-
ity.
Mean course error
means the mean
value of the azimuth error along a
specified radial of the azimuth func-
tion.
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 equip-
ment failures over a given period.
852
14 CFR Ch. I (1–1–24 Edition)
§ 171.305
Microwave Landing System (MLS)
means the MLS selected by ICAO for
international standardization.
Minimum glidepath
means the lowest
angle of descent along the zero degree
azimuth that is consistent with pub-
lished approach procedures and obsta-
cle clearance criteria.
MLS Approach Reference Datum
is a
point at a specified height located
vertically above the intersection of the
runway centerline and the threshold.
MLS back azimuth reference datum
means a point 15 meters (50 feet) above
the runway centerline at the runway
midpoint.
MLS datum point
means a point de-
fined by the intersection of the runway
centerline with a vertical plane perpen-
dicular to the centerline and passing
through the elevation antenna phase
center.
Out of coverage indication (OCI)
means
a signal radiated into areas outside the
intended coverage sector, where re-
quired, to specifically prevent invalid
removal of an airborne warning indica-
tion in the presence of misleading guid-
ance information.
Path Following Error (PFE)
means the
guidance perturbations which could
cause aircraft displacement from the
desired course or glidepath. It is com-
posed of the path following noise and of
the mean course error in the case of
azimuth functions, or the mean glide-
path error in the case of elevation
functions. Path following errors are
evaluated by filtering the flight error
record with a second order low pass fil-
ter which has a corner frequency at 0.5
radian/sec for azimuth data or 1.5 radi-
ans/sec for elevation data.
Path following noise (PFN)
means that
portion of the guidance signal error
which could cause displacement from
the actual mean course line or mean
glidepath as appropriate.
Split-site ground station
means the
type of ground station in which the azi-
muth portion of the ground station is
located near the stop end of the run-
way, and the elevation portion is lo-
cated near the approach end.
Time division multiplex (TDM)
means
that each function is transmitted on
the same frequency in time sequence,
with a distinct preamble preceding
each function transmission.
§ 171.305 Requests for IFR procedure.
(a) Each person who requests an IFR
procedure based on an MLS facility
which that person owns must submit
the following information with that re-
quest:
(1) A description of the facility and
evidence that the equipment meets the
performance requirements of §§ 171.309,
171.311, 171.313, 171.315, 171.317, 171.319,
and 171.321 and is fabricated and in-
stalled in accordance with § 171.323.
(2) A proposed procedure for oper-
ating the facility.
(3) A proposed maintenance organiza-
tion and a maintenance manual that
meets the requirements of § 171.325.
(4) A statement of intent to meet the
requirements of this subpart.
(5) A showing that the facility has an
acceptable level of operational reli-
ability and an acceptable standard of
performance. Previous equivalent oper-
ational experience with a facility with
identical design and operational char-
acteristics will be considered in show-
ing compliance with this subparagraph.
(b) FAA inspects and evaluates the
MLS facility; it advises the owner of
the results, and of any required
changes in the MLS facility or in the
maintenance manual or maintenance
organization. The owner must then
correct the deficiencies, if any, and op-
erate the MLS facility for an in-service
evaluation by the FAA.
§ 171.307 Minimum requirements for
approval.
(a) The following are the minimum
requirements that must be met before
the FAA approves an IFR procedure for
a non-Federal MLS facility:
(1) The performance of the MLS facil-
ity, as determined by flight and ground
inspection conducted by the FAA, must
meet the requirements of §§ 171.309,
171.311, 171.313, 171.315, 171.317, 171.319,
and 171.321.
(2) The fabrication and installation of
the equipment must meet the require-
ments of § 171.323.
(3) The owner must agree to operate
and maintain the MLS facility in ac-
cordance with § 171.325.
(4) The owner must agree to furnish
operational records as set forth in
§ 171.327 and agree to allow the FAA to