AIM

8/15/19

5

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8

Arrival Procedures

altitude is specified in the ATC clearance, that altitude be-
comes mandatory as defined above.

2.

The ILS glide slope is intended to be intercepted at the

published glide slope intercept altitude. This point marks
the PFAF and is depicted by the ”lightning bolt” symbol
on U.S. Government charts. Intercepting the glide slope
at this altitude marks the beginning of the final
approach segment and ensures required obstacle clear-
ance during descent from the glide slope intercept altitude
to the lowest published decision altitude for the approach.
Interception and tracking of the glide slope prior to the
published glide slope interception altitude does not
necessarily ensure that minimum, maximum, and/or
mandatory altitudes published for any preceding fixes
will be complied with during the descent. If the pilot
chooses to track the glide slope prior to the glide slope
interception altitude, they remain responsible for comply-
ing with published altitudes for any preceding stepdown
fixes encountered during the subsequent  descent.

3.

Approaches used for simultaneous (parallel) independ-

ent and simultaneous close parallel operations
procedurally require descending on the glideslope from the
altitude at which the approach clearance is issued (refer to
5-4-15 and 5-4-16). For simultaneous close parallel
(PRM) approaches, the Attention All Users Page (AAUP)
may publish a note which indicates that descending on the
glideslope/glidepath meets all crossing restrictions.
However, if no such note is published, and for simultaneous
independent approaches (4300 and greater runway
separation) where an AAUP is not published, pilots are
cautioned to monitor their descent on the glideslope/path
outside of the PFAF to ensure compliance with published
crossing restrictions during simultaneous operations.

4.

When parallel approach courses are less than 2500 feet

apart and reduced in-trail spacing is authorized for
simultaneous dependent operations, a chart note will
indicate that simultaneous operations require use of
vertical guidance and that the pilot should maintain last
assigned altitude until established on glide slope.  These
approaches procedurally require utilization of the ILS
glide slope for wake turbulence mitigation. Pilots should
not confuse these simultaneous dependent operations with

(SOIA) simultaneous close parallel PRM approaches,
where PRM appears in the approach title.

5.

Altitude restrictions depicted at stepdown

fixes within the final approach segment are
applicable only when flying a Non

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Precision

Approach to a straight

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in or circling line of minima

identified as a MDA(H). Stepdown fix altitude
restrictions within the final approach segment do not
apply to pilots using Precision Approach (ILS) or
Approach with Vertical Guidance (LPV, LNAV/
VNAV) lines of minima identified as a DA(H), since
obstacle clearance on these approaches are based on
the aircraft following the applicable vertical
guidance. Pilots are responsible for adherence to
stepdown fix altitude restrictions when outside the
final approach segment (i.e., initial or intermediate
segment), regardless of which type of procedure the
pilot is flying. (See FIG 5

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4

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1.)

c. Minimum Safe Altitudes (MSA)

 are published

for emergency use on IAP charts. MSAs provide
1,000 feet of clearance over all obstacles, but do not
necessarily assure acceptable navigation signal
coverage. The MSA depiction on the plan view of an
approach chart contains the identifier of the center
point of the MSA, the applicable radius of the MSA,
a depiction of the sector(s), and the minimum
altitudes above mean sea level which provide
obstacle clearance. For conventional navigation
systems, the MSA is normally based on the primary
omnidirectional facility on which the IAP is
predicated, but may be based on the airport reference
point (ARP) if no suitable facility is available. For
RNAV approaches, the MSA is based on an RNAV
waypoint. MSAs normally have a 25 NM radius;
however, for conventional navigation systems, this
radius may be expanded to 30 NM if necessary to
encompass the airport landing surfaces. A single
sector altitude is normally established, however when
the MSA is based on a facility and it is necessary to
obtain relief from obstacles, an MSA with up to four
sectors may be established.