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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