AIM

8/15/19

5

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26

En Route Procedures

(5)

Some RNAV systems compute the

holding pattern based on the aircraft’s altitude and
speed at a point prior to entering the hold. If the
indicated airspeed is not reduced to comply with the
maximum holding speed before this point, the
computed pattern may exceed the protected airspace.
Loading or executing a holding pattern may result in
the speed and time limits applicable to the aircraft’s
current altitude being used to define the holding
pattern for RNAV lateral guidance. This may result in
an incorrect hold being flown by the RNAV system.
For example, entering or executing the holding
pattern above 14,000 feet when intending to hold
below 14,000 feet may result in applying 1 

½

  minute

timing below 14,000 feet.

NOTE

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Some systems permit the pilot to modify leg time of  holding
patterns defined in the navigation database; for example,
a hold

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in

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lieu of procedure turn. In most RNAV systems,

the holding pattern time remains at the pilot

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modified time

and will not revert back to the coded time if the aircraft
descends to a lower altitude where a shorter time interval
applies.

(b)

RNAV systems are not able to alert the

pilot for excursions outside of holding pattern
protected airspace since the dimensions of this
airspace are not included in the navigation database.
In addition, the dimensions of holding pattern
protected airspace vary with altitude for a charted
holding pattern, even when the hold is used for the
same application. Close adherence to the pilot actions
described in this section reduce the likelihood of
exceeding the boundary of holding pattern protected
airspace when using RNAV lateral guidance to
conduct holding.

(c)

Holding patterns may be stored in the

RNAV system’s navigation database and include
coding with parameters defining how the RNAV
system will conduct the hold. For example, coding
will determine whether holding is conducted to
manual termination (HM), continued holding until
the aircraft reaches a specified altitude (HA), or
holding is conducted until the holding fix is crossed
the first time after entry (HF). Some systems do not
store all holding patterns, and may only store patterns
associated with missed approaches and hold

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in

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lieu

of procedure turn (HILPT). Some store all holding as
standard patterns and require pilot action to conduct
non

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standard holding (left turns).

(1)

Pilots are cautioned that multiple

holding patterns may be established at the same fix.
These holding patterns may differ in respect to turn
directions and leg lengths depending on their
application as an en route holding pattern, a holding
pattern charted on a SID or STAR, or when used on
an instrument approach procedure. Many RNAV
systems limit the database coding at a particular fix to
a single holding pattern definition. Pilots extracting
the holding pattern from the navigation database are
responsible for confirming that the holding pattern
conforms to the assigned charted holding pattern in
terms of turn direction, speed limit, timing, and
distance.

(2)

If ATC assigns holding that is not

charted, then the pilot is responsible for programming
the RNAV system with the assigned holding course,
turn direction, speed limit, leg length, or leg time.

(3)

Changes made after the initial execu-

tion may not apply until the next circuit of the holding
pattern if the aircraft is in close proximity to the
holding fix.

8. Pilot Action.

 The following actions are

recommended to ensure that the aircraft remains
within holding protected airspace when holding is
performed using either conventional NAVAID
guidance or when using RNAV lateral guidance.

(a)

Speed. When ATC furnishes advance

notice of holding, start speed reduction to be at or
below the maximum holding speed allowed at least 3
minutes prior to crossing the holding fix. If advance
notice by ATC is not provided, begin speed reduction
as expeditiously as practical. It is acceptable to allow
RNAV systems to determine an appropriate decelera-
tion point prior to the holding fix and to manage the
speed reduction to the RNAV computed holding
speed. If the pilot does not permit the RNAV system
to manage the deceleration from the computed point,
the actual hold pattern size at holding entry may differ
from the holding pattern size computed by the RNAV
system.

(1)

Aircraft are expected to enter holding at

or below the maximum holding speed established in
paragraph 5

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3

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8 j 2(a) or the charted maximum

holding speed.

[a]

All fixed wing aircraft conducting

holding should fly at speeds at or above 90 KIAS to
minimize the influence of wind drift.