AIM 

4/20/23

 

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4

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8

Arrival Procedures

1.

Minimum altitude will be depicted with the altitude value underscored. Aircraft are required to maintain

altitude at or above the depicted value, e.g., 3000.

2.

Maximum altitude will be depicted with the altitude value overscored. Aircraft are required to maintain

altitude at or below the depicted value, e.g., 4000.

3.

Mandatory altitude will be depicted with the altitude value both underscored and overscored. Aircraft

are required to maintain altitude at the depicted value, e.g., 5000.

4.

Recommended altitude will be depicted with no overscore or underscore. These altitudes are depicted

for descent planning, e.g., 6000.

NOTE

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1.

Pilots are cautioned to adhere to altitudes as prescribed because, in certain instances, they may be used as the basis for

vertical separation of aircraft by ATC. When a depicted altitude is specified in the ATC clearance, that altitude becomes
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 clearance 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 complying with published altitudes
for any preceding stepdown fixes encountered during the subsequent  descent.

3.

Approaches used for simultaneous (parallel) independent and simultaneous close parallel operations procedurally

require descending on the glideslope from the altitude at which the approach clearance is issued (refer to 5

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4

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15 and

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4

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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 an MDA (H).

These altitude restrictions may be annotated with a note “LOC only” or “LNAV only.” 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 is 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.

The 

Minimum Safe Altitudes (MSA)

 is published for emergency use on IAP or departure procedure (DP)

graphic 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 or on a DP graphic 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 or DP
graphic chart is predicated, but may be based on the airport reference point (ARP) if no suitable facility is
available. For RNAV approaches or DP graphic charts, 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