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United Kingdom Overseas Territories Aviation Circular

0B

OTAC 39-17
91-12
121-17
125-15
135-17

Performance Based Navigation (PBN) Approvals

Issue 3.00
17 May 2024

Effective: On issue

GENERAL

Overseas Territories Aviation Circulars are issued to provide advice, guidance and information
on standards, practices and procedures necessary to support Overseas Territory Aviation
Requirements. They are not in themselves law but may amplify a provision of the Air Navigation
(Overseas Territories) Order or provide practical guidance on meeting a requirement contained
in the Overseas Territories Aviation Requirements.

PURPOSE

This Overseas Territories Aviation Circular provides information regarding Performance Based
Navigation and the requirements of both the AN(OT)O and OTAR Parts 121 and 135 for
obtaining an approval. This guidance is also intended to provide an indication of the level of
knowledge and investment in resources (both human and hardware) necessary before an
operator is ready to commence the process of applying for PBN approval.

RELATED REQUIREMENTS

This Circular relates to Part 8 (Height Keeping and Navigation) of the AN(OT)O 2013 and to
Part SPA (Specific Approvals, Section II – Operations in areas with specified navigational
performance) of OTAR Parts 39, 91, 125, 121 and 135.

CHANGE INFORMATION

Issue 3. Amendment to weblinks in Section 6.

ENQUIRIES

Enquiries regarding the content of this Circular should be addressed to Air Safety Support
International at the address on the ASSI website www.airsafety.aero or to the appropriate
Overseas Territory Aviation Authority.

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Contents

EXPLANATION OF TERMS ASSOCIATED WITH PERFORMANCE BASED NAVIGATION ....... 3

1 Introduction ..................................................................................................................4
2 Overview of Performance Based Navigation (PBN) .................................................... 4
3 PBN Operational approval requirements ..................................................................... 7
4 PBN Operational approvals .......................................................................................10
5 Obtaining an approval ...............................................................................................10
6 Further reading ..........................................................................................................11
APPENDIX A PBN CERTIFICATION STANDARDS ................................................................... 12

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EXPLANATION OF TERMS ASSOCIATED WITH PERFORMANCE BASED

NAVIGATION
Note: Not all of these terms are used in this OTAC.

Aircraft-based augmentation system (ABAS). An augmentation system that augments and/or

integrates the information obtained from the other GNSS elements with information available on
board the aircraft.
Note: The most common form of ABAS is receiver autonomous integrity monitoring (RAIM).
Approach procedure with vertical guidance (APV). An instrument procedure which utilizes
lateral and vertical guidance but does not meet the requirements established for precision
approach and landing operations.
Area navigation (RNAV). A method of navigation which permits aircraft operation on any
desired flight path within the coverage of ground or space-based navigation aids or within the
limits of the capability of self-contained aids, or a combination of these.
Global Navigation Satellite System (GNSS). The standard generic term for satellite navigation
systems that provide autonomous geo-spatial positioning with global coverage.
Navigation aid (NAVAID) infrastructure. NAVAID infrastructure refers to space-based and or
ground-based NAVAIDs available to meet the requirements in the navigation specification.
Navigation specification. A set of aircraft and aircrew requirements needed to support
Performance-based Navigation operations within a defined airspace. There are two kinds of
navigation specification:
RNAV specification. A navigation specification based on area navigation that does not
include the requirement for on-board performance monitoring and alerting, designated by
the prefix RNAV, eg RNAV 5, RNAV 1.
RNP specification. A navigation specification based on area navigation that includes the
requirement for on-board performance monitoring and alerting, designated by the prefix
RNP, eg RNP 4, RNP APCH.
Performance-Based Navigation (PBN). Area navigation based on performance requirements
for aircraft operating along an ATS route, on an instrument approach procedure or in a
designated airspace.
Note: Performance requirements are expressed in navigation specifications in terms of
accuracy, integrity, continuity and functionality needed for the proposed operation in the
context of a particular airspace concept. Availability of GNSS or some other NAVAID
infrastructure is considered within the airspace concept in order to enable the navigation
application.
Receiver Autonomous Integrity Monitoring (RAIM). A form of ABAS whereby a GNSS
receiver processor determines the integrity of the GNSS navigation signals using only GPS
signals or GPS signals augmented with altitude (baro-aiding). This determination is achieved by
a consistency check among redundant pseudo-range measurements. At least one additional
satellite needs to be available with the correct geometry over and above that needed for the
position estimation, for the receiver to perform the RAIM function.
RNAV operations. Aircraft operations using area navigation for RNAV applications.
RNAV system. A navigation system which permits aircraft operation on any desired flight path
within the coverage of station-referenced navigation aids or within the limits of the capability of
self-contained aids, or a combination of these. An RNAV system may be included as part of a
flight management system (FMS).
RNP operations. Aircraft operations using an RNP system for RNP navigation applications.
Satellite-based Augmentation System (SBAS). A wide coverage augmentation system in
which the user receives augmentation information from a satellite-based transmitter.
RNP system. An area navigation system which supports on-board performance monitoring and
alerting.

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Performance Based Navigation (PBN) Approvals Issue 3.00 OTAC 39-17, 91-12, 121-17, 125-15, 135-17

1 Introduction
1.1 The Air Navigation (Overseas Territories) Order requires that a Territory-registered
aircraft must not fly in areas with specified performance navigation unless it is
equipped with navigation equipment that complies with published requirements
and the operator has been approved by the Governor.

1.2 OTAR Parts 91, 125, 135 & 121, (Part SPA Section II, Operations in areas with
specified navigational performance), requires that the operator satisfies the
following in order to gain such an approval:

a) demonstrate that the navigation equipment meets the required performance

in terms of navigation functionality, accuracy, integrity, availability and
continuity; and

b) establish and maintain a training programme for the flight crew involved in
these operations; and

c) establish operating procedures specifying:

(i) the equipment to be carried, including its operating limitations and

appropriate entries in the Minimum Equipment List (MEL);
(ii) flight crew composition and experience requirements;
(iii) normal procedures;
(iv) contingency procedures;
(v) incident reporting;
(vi) navigation database integrity.

2 Overview of Performance Based Navigation (PBN)

2.1 Conventional navigation is dependent upon ground-based radio navigation aids,
which have been the mainstay of aviation for the last seventy years, and pilots,
operators, manufacturers and Air Navigation Service Providers (ANSPs) are all
familiar with the associated technology, avionics, instrumentation, operations,
training and performance.

2.2 Performance-based navigation (PBN) detailed in the International Civil Aviation

Organisation’s (ICAO) ‘Performance-based Navigation (PBN) Manual (ICAO Doc
9613), is based upon area navigation principles. While various methods of area
navigation have been in existence for many years, the widespread use of area
navigation as a primary navigation function is a more recent phenomenon. The
PBN concept is intended to better define the use of area navigation systems and is
expected to replace many of the existing conventional navigation routes in the
future.

2.3 The fundamentals of PBN operations are relatively straightforward; however, the
transition to new technology, new navigation and new operational concepts and
the dependence on data-driven operations require careful management. The PBN
operational approval process is intended to ensure that the appropriate level of
implementation and oversight is provided for all PBN operations and the benefits of
PBN are achieved consistently and safely.

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2.4 There are 3 components to PBN:

a) Navigation Specifications

A navigation specification details the performance required of the RNAV or

RNP system in terms of accuracy, integrity, and continuity; which navigation
functionalities the RNAV or RNP system must have; which navigation
sensors must be integrated into the RNAV or RNP system; and which
requirements are placed on the flight crew. An RNP specification includes a
requirement for on-board performance monitoring and alerting, while an
RNAV specification does not. On-board performance monitoring and alerting
is the main element that determines whether the navigation system complies
with the necessary safety level associated with an RNP application; whether
it relates to both lateral and vertical navigation performance; and whether it
allows the aircrew to detect that the navigation system is not achieving, or
cannot guarantee with 10–5 integrity, the navigation performance required for
the operation.

b) Navigation Applications

A navigation application is the use of a navigation specification and associated

NAVAID infrastructure to ATS routes, instrument approach procedures and/or
defined airspace. An RNP application is supported by an RNP specification; an
RNAV application is supported by an RNAV specification.

c) RNP/RNAV Designations

RNP and RNAV designations are based upon lateral accuracy in nautical
miles. An aircraft must remain + or – the numerical value stated (in nautical
miles) for 95% of the total flight time:

RNP Designations
(requires on-board performance monitoring and alerting)
RNP 0.3
(Helicopter
Operations) En-Route and terminal
RNP 1 navigation applications
RNP 2 Oceanic and remote
navigation applications
RNP 4 Oceanic and remote
navigation applications
A-RNP
RNP APCH En-Route and terminal
navigation applications
RNP AR APCH

RNAV Designations
(no requirement for on-board performance monitoring and alerting)
RNAV 1
En-Route and terminal
RNAV 2
navigation applications
RNAV 5
RNAV 10 Oceanic and remote
navigation applications

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RNP Approach Designations

(i) Non-Precision or 2D Approaches

LNAV (Lateral Navigation): This is a Non-Precision or 2D Approach

with Lateral only navigation guidance provided by GNSS.
LP (Localiser Performance): This is a Non-Precision or 2D Approach
with Lateral only navigation guidance provided by GNSS.

(ii) APV 3D Approaches

(Note: VNAV (Vertical Navigation). APV (Approach with Vertical

Guidance): defined as an instrument procedure which utilises lateral and
vertical guidance but does not meet the requirements established for
precision approach and landing operations.)

LNAV/VNAV (also known as APV/Baro VNAV): This is a 3D Approach

Procedure with Vertical Guidance. The lateral navigation
guidance is provided by GNSS. The vertical guidance is provided
by a Barometric Altimeter.
LPV (Localiser Performance with Vertical Guidance): This is a 3D
Approach Procedure with both the Lateral and Vertical guidance
provided by GNSS.

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d) Navaid Infrastructure

The NAVAID infrastructure refers to ground- or space-based NAVAIDs.

Ground-based NAVAIDs include DME and VOR. Space-based NAVAIDs
include GNSS elements.

2.5 PBN requires that aircraft meet certain airworthiness certification standards,
including the necessary navigation system performance and functionality, as well
as development of the operator’s flight operations procedures and flight crew
training/competency requirements:

a) Airworthiness: The airworthiness element ensures that the aircraft meets

aircraft eligibility and safety requirements for the functions and performance
defined in the navigation specifications. The installation will need to meet the
relevant airworthiness standards, eg US 14 CFR Part 25/EASA CS-25 and
the applicable AC/AMC. The AC/AMC may also include other non-navigation
equipment required to conduct the operation such as communications and
surveillance equipment.

b) Continued Airworthiness: The operator is expected to demonstrate that the

navigation system will be maintained compliant with the type design. For
navigation system installations there are few specific continued airworthiness
requirements other than database and configuration management, systems
modifications and software revisions.

c) Flight Operations: The flight operations element considers the operator’s

infrastructure for conducting PBN operations, including flight crew operating
procedures, training (to include classroom and flight training, initial and
recurrent, and competency demonstrations). This element also considers the
operator’s Minimum Equipment List (MEL), Operations Manual (OM),
checklists, instrument flight procedure approval processes, navigation
database validation procedures, flight planning and dispatch procedures, etc.

3 PBN Operational approval requirements

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3.1 AIRWORTHINESS

a) Airworthiness Approval

(i) An aircraft is eligible for a particular PBN application provided there is

a clear statement of its PBN capability in the TC (Type Certificate),
the STC (Supplemental Type Certificate), or the associated
documentation — AFM or equivalent document; or a compliance
statement from the manufacturer, which has been approved by the
State of Design. The operator must have a configuration list detailing
the pertinent hardware and software components and equipment
used for the PBN operation.
(ii) The aircraft shall be required to hold an airworthiness approval or
have been modified in accordance with approved data (often a
Supplemental Type Certificate), for the type of envisaged PBN, for its
navigation system operations.
(iii) Guidance on the certification standards that are often referenced in
the AFM/RFM sections associated with PBN is given in Appendix A.

b) Continued Airworthiness

(i) Procedures shall be in place to maintain the aircraft to conform to its

type design and with the requirements for all navigation approvals held.
(ii) The aircraft maintenance programme must take account of all
operational approvals and maintain navigation systems so that they are
compliant with navigation approvals.
(iii) The continuing airworthiness management organisations and their
contracted maintenance organisation shall ensure that staff have
received PBN training.

3.2 FLIGHT OPERATIONS

a) Minimum Equipment List (MEL)

The MEL should identify the minimum equipment necessary to satisfy the
intended navigation function required.

b) Electronic Navigation Data Management

Procedures shall be in place for electronic navigation data products, that are
for use in the air and on the ground, to ensure:

(i) acceptable standards of data integrity and compatibility with the

intended function;
(ii) continual monitoring of the related data processes and the products; and
(iii) the timely distribution and insertion of electronic navigation data.

In accordance with ICAO Doc 9613 databases for RNAV 1, RNAV 2, RNP 2,
RNP 1, RNP 4, RNP APCH, RNP AR APCH, A-RNP and RNP 0.3 operations
should have a Type 2 Letter of Acceptance (LoA) issued to the database
suppler from the appropriate regulatory authority.

A copy of this LoA should be provided to the operator.

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The LoA confirms the database meets the data quality requirements of RTCA
DO200A/EUROCAE document ED 76, Standards for Processing
Aeronautical Data.

A Type 2 LoA permits a databases supplier to deliver a Navigation database

product to end users.

c) Flight Crew composition and experience requirements

The Operations Manual should contain details of the crew composition

required for PBN operations, the qualifications required and the experience
required to obtain those qualifications.

d) Standard operating procedures (SOPs)

Standard operating procedures (SOPs) must be developed to cover both

normal and non-normal (contingency) procedures for the systems used in the
PBN operation. The SOPs must be documented in the OM and address the
following:

(i) preflight planning requirements, including the MEL, appropriate navaids,

the navigation database, and, where appropriate, RNP/RAIM prediction;
(ii) actions to be taken prior to commencing the PBN operation;
(iii) actions to be taken during the PBN operation;
(iv) actions to be taken in the event of a contingency (e.g. equipment failures
and/or weather conditions) that could affect the aircraft’s ability to
maintain navigation accuracy. These procedures would also require the
flight crew to state their intentions, coordinate a plan of action and obtain
a revised ATC clearance in case of contingencies, including the
reporting to the operator and to the Overseas Territory Aviation Authority
(OTAA) of significant incidents.

e) Monitoring and incident reporting

Flight crew responsibilities must be laid down in SOPs, with respect to the
performance monitoring and alerting provided by the navigation system,
together with reporting to the operator and OTAA of significant incidents such
as:

(i) navigation errors not associated with transitions from an inertial

navigation mode to a radio navigation mode;
(ii) unexpected deviations in lateral or vertical flight path attributed to
incorrect navigation data;
(iii) significant misleading information without failure warning;
(iv) total loss or multiple failures of the PBN navigation equipment; or
(v) problems with ground navigation facilities leading to significant
navigation errors.

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e) Training programme

Each pilot must receive appropriate training, briefings and guidance material
in order to safely conduct any operation. The training programme needs to
cover both ground training and flight training and to cover the following areas:

(i) Area navigation principles;

(ii) Navigation system principles;
(iii) Equipment operation and functionality;
(iv) Flight planning;
(v) Operating procedures;
(vi) Performance monitoring and alerting.

f) Recurrent Training

The flight crew training programme must include provision for the
management of recurrent training and the demonstration of competency.

4 PBN Operational approvals

Operational Approvals, in accordance with the AN(OT)O, are stated on the Operation
Specifications section of the Air Operator Certificate and detail the PBN approvals that
an operator has been granted and, therefore, the PBN operations they are authorised
to conduct:

RNP & APV 3D Approach RNAV & Non-Precision 2D

Designations Approach Designations

RNP 0.3 * RNAV 1

RNP 1 RNAV 2

RNP 2 RNAV 5

RNP 4 RNAV 10

RNP APCH (LNAV) LNAV

RNP APCH (LPV) LP

RNP APCH (LNAV/VNAV)

* RNP 0.3 is intended for helicopter operations

5 Obtaining an approval
For details on the process for applying for a PBN approval, operators/owners will need
to contact the relevant OTAA.

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6 Further reading
Skybrary:
https://www.skybrary.aero/index.php/Performance_Based_Navigation_(PBN)

Doc 9613: Performance-Based Navigation Manual:

Available at the above Skybrary link

Eurocontrol:
https://www.eurocontrol.int/concept/performance-based-navigation
END

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APPENDIX A

PBN Certification Standards

This Appendix provides an overview of the certification requirements associated with the
various PBN Specifications. It is intended to assist OTAAs in determining the compliance
status of the installed systems on the aircraft. Usually this will be accomplished by reviewing
the AFM supplement and assessing the compliance declarations in the Limitations section,
together with the STC drawings and data.

The PBN specification is given in the left column, the European and FAA requirements are in
the centre columns. Additional information such as required input sensors and the application
use of the PBN specification are given in the right column.

For background information, regarding the European standards, the JAA then EASA initially
used JAA TGLs as the certification basis for some RNAV applications. Then as EASA
progressed from 2003 it produced AMC20 documents to address some more of the
applications. In 2019 EASA created a dedicated Certification Specification CS-ACNS to
address all the applicable PBN Specifications. The CS-ACNS document will be used for new
PBN related STCs and Design Changes. In the OTAA’s it is more likely that for the present,
the compliance will be against the older standards (ie TGLs and EASA AMC 20 documents).

PBN Spec European FAA Other Information

Certification
Requirements
RNAV 5 AMC 20-4A; JAA 20-138D App, Can use VOR/DME;
TGL 2; CS-ACNS AC90-96A DME/DME; GNSS and/or INS
Subpart C Sub 2; sensors. Was known as Basic
RNAV. Used Continental En-
Route
RNAV 1 JAA TGL 10; CS- AC20-138D DME/DME; DME/DME/IRU or
ACNS Subpart C AC90-100A GNSS. Used En-Route
Sub 2 Continental, arrival, and
departure and Intermediate
Approach.
Database requires a LoA.
RNAV 2 CS-ACNS Subpart AC-20-138D DME/DME; DME/DME/IRU or
C Sub 2; ICAO 90-100A GNSS. Used En-Route
Doc 9613 Continental, arrival, and
departure.
Database requires a LoA.
RNAV 10 AMC 20-12; CS- FAA Order least two independent and
ACNS Subpart C 8400.12a, serviceable LRNSs
Sub 2 AC20-138D & comprising an INS, an IRS
Appendix 1 FMS or a GNSS. Used in
AC90-105A Oceanic/Remote.
Database requires a LoA.
RNP 1 CS-ACNS Subpart AC20-138D GNSS. Used for arrival and
C Sub 1,2 AC90-105A departure.
Database requires a LoA.
RNP 2 CS-ACNS Subpart AC20-138D GNSS. Used Oceanic, En-
C Sub 1,2 AC90-105A Route Continental and
Remote Operations
Database requires a LoA.

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RNP 4 ICAO Doc 9613; AC20-138D & 2 Independent LRNs with

CS-ACNS Subpart Appendix 1; GNSS. Used
C Sub 1,2,10 FAA Order Oceanic/Remote.
8400.33 Database requires a LoA.
AC90-105A
RNP APCH with AMC20-27A; CS- AC20-138D Tends to be installed on Large
Baro VNAV ACNS Subpart C AC90-105A aircraft (Airbus/Boeing).
Sub 1,2, 3, 5 GNSS and Baro VNAV.
Database requires a LoA.
LPV Approach AMC20-28; CS- AC20-138D Small Business jet and
using SBAS ACNS Subpart C AC90-105A Retrofit applications. GNSS
Sub 1,2,3, 5 Augmented with
WAAS/EGNOSS. Database
requires a LoA.
RNP AR APCH AMC-26A; CS- AC20-138D & GNSS and Baro VNAV.
ACNS Subpart C Appendix 2 Database requires a LoA.
Sub 1,2,3,4, 5,6, 8 Requires a TAWS and AP/FD
coupling
A-RNP CS-ACNS Subpart AC20-138D & GNSS Based, Covers RNAV 5
C Sub 1,2,3,5, 7, Appendix 3 RNAV 1 RNAV 2 RNP 2 RNP
8, 10 AC90-105A 1 RNP APCH. Database
requires a LoA
RNP 0.3 CS-ACNS Subpart AC20-138D GNSS based. Used for
C Sub 1,2 AC90-105A Helicopters only. Requires
Database requires a LoA.
Requires AP/FD coupling

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