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AIM

10/12/17

5

−4−51

Arrival Procedures

operational procedures (e.g., GPS inoperative, use of
flight director vice autopilot).

2. Curved path procedures.

Some RNP ap-

proaches have a curved path, also called a
radius

−to−a−fix  (RF) leg. Since not all aircraft have

the capability to fly these arcs, pilots are responsible
for knowing if they can conduct an RNP approach
with an arc or not. Aircraft speeds, winds and bank
angles have been taken into consideration in the
development of the procedures.

3. RNP required for extraction or not.

Where required, the missed approach procedure may
use RNP values less than RNP

−1. The reliability of

the navigation system has to be very high in order to
conduct these approaches. Operation on these
procedures generally requires redundant equipment,
as no single point of failure can cause loss of both
approach and missed approach navigation.

4. Non

−standard speeds or climb gradients.

RNP AR approaches are developed based on standard
approach speeds and a 200 ft/NM climb gradient in
the missed approach. Any exceptions to these
standards will be indicated on the approach
procedure, and the operator should ensure they can
comply with any published restrictions before
conducting the operation.

5. Temperature Limits.

For aircraft using

barometric vertical navigation (without temperature
compensation) to conduct the approach, low and
high

−temperature limits are identified on the

procedure. Cold temperatures reduce the glidepath
angle while high temperatures increase the glidepath
angle. Aircraft using baro VNAV with temperature
compensation or aircraft using an alternate means for
vertical guidance (e.g., SBAS) may disregard the
temperature restrictions. The charted temperature
limits are evaluated for the final approach segment
only. Regardless of charted temperature limits or
temperature compensation by the FMS, the pilot may
need to manually compensate for cold temperature on
minimum altitudes and the decision altitude.

6. Aircraft size.

The achieved minimums may

be dependent on aircraft size. Large aircraft may
require higher minimums due to gear height and/or
wingspan. Approach procedure charts will be
annotated with applicable aircraft size restrictions.

b. Types of RNP AR Approach Operations

1. RNP Stand

−alone Approach Operations.

RNP AR procedures can provide access to runways
regardless of the ground

−based NAVAID infrastruc-

ture, and can be designed to avoid obstacles, terrain,
airspace, or resolve environmental constraints.

2. RNP Parallel Approach (RPA) Opera-

tions. 

RNP AR procedures can be used for parallel

approaches where the runway separation is adequate
(See FIG 5

−4−26). Parallel approach procedures can

be used either simultaneously or as stand

−alone

operations. They may be part of either independent or
dependent operations depending on the ATC ability
to provide radar monitoring.

FIG 5

−4−26

3. RNP Parallel Approach Runway Transi-

tions (RPAT) Operations.

RPAT approaches begin

as a parallel IFR approach operation using
simultaneous independent or dependent procedures.
(See FIG 5

−4−27). Visual separation standards are

used in the final segment of the approach after the
final approach fix, to permit the RPAT aircraft to
transition in visual conditions along a predefined
lateral and vertical path to align with the runway
centerline.

3/29/18

AIM