Sec. 171.319 - Approach elevation monitor system
(a) The monitor system must act to
ensure that any of the following conditions do not persist for longer than
the periods specified when:
(1) There is a change in the ground
component contribution to the mean glidepath error component such that the
path following error on any glidepath exceeds the limits specified in
§171.317(d) for a period of more than one second.
Note: The above requirement and the requirement
to limit the ground equipment mean error to ±0.067 degree can be satisfied
by the following procedure. The integral monitor alarm limit should be set
to ±0.067 degree. This will limit the electrical component of mean
glidepath error to ±0.067 degree. The field monitor alarm limit should be
set such that with the mean glidepath error at the alarm limit the total
allowed PFE is not exceeded on any commissioned glidepath from the limit
of coverage to an altitude of 100 feet.
(2) There is a reduction in the radiated
power to a level not less than that specified in §171.317(a)(4) for a
period of more than one second.
(3) There is an error in the preamble
DPSK transmission which occurs more than once in any one second period.
(4) There is an error in the time
division multiplex synchronization of a particular elevation function such
that the requirement specified in §171.311(e) is not satisfied and this
condition persists for more than one second.
(5) A failure of the monitor is
(b) The period during which erroneous
guidance information is radiated must not exceed the periods specified in
§171.319(a). If the fault is not cleared within the time allowed,
radiation shall cease. After shutdown, no attempt must be made to restore
service until a period of 20 seconds has elapsed.