AIM

8/15/19

5

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3

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23

En Route Procedures

cannot be determined, start timing when turn to
outbound is completed.

5. Distance Measuring Equipment (DME)/

GPS Along

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Track Distance (ATD). 

DME/GPS

holding is subject to the same entry and holding
procedures except that distances (nautical miles) are
used in lieu of time values. The outbound course of
the DME/GPS holding pattern is called the outbound
leg of the pattern. The controller or the instrument
approach procedure chart will specify the length of
the outbound leg. The end of the outbound leg is
determined by the DME or ATD readout. The holding
fix on conventional procedures, or controller defined

holding based on a conventional navigation aid with
DME, is a specified course or radial and distances are
from the DME station for both the inbound and
outbound ends of the holding pattern. When flying
published GPS overlay or stand alone procedures
with distance specified, the holding fix will be a
waypoint in the database and the end of the outbound
leg will be determined by the ATD. Some GPS
overlay and early stand alone procedures may have
timing specified. (See FIG 5

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3

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5, FIG 5

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3

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6 and

FIG 5

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3

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7.) See Paragraph 1

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1

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17, Global Position-

ing System (GPS), for requirements and restriction
on using GPS for IFR operations.

FIG 5

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3

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5

Inbound Toward NAVAID

NOTE

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When the inbound course is toward the NAVAID, the fix distance is 10 NM, and the leg length is 5 NM, then the end of the
outbound leg will be reached when the DME reads 15 NM.

FIG 5

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3

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6

Inbound Leg Away from NAVAID

NOTE

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When the inbound course is away from the NAVAID and the fix distance is 28 NM, and the leg length is 8 NM, then the end
of the outbound leg will be reached when the DME reads 20 NM.