I, John francis Mccormick, Director of Aviation Safety, on behalf of CASA, make this instrument under regulations 207 and 232A of the Civil Aviation Regulations 1988.
[Signed John F. McCormick]
John F. McCormick
Director of Aviation Safety
21 December 2011
Civil Aviation Order 20.18 Amendment Instrument 2011 (No. 1)
1 Name of instrument
This instrument is the Civil Aviation Order 20.18 Amendment Instrument 2011 (No. 1).
This instrument commences on the 28th day after registration.
3 Amendment of Civil Aviation Order 20.18
Schedule 1 amends Civil Aviation Order 20.18.
Schedule 1 Amendment
 Subsection 9A, the title
Directions relating to use of navigation computer systems
 Paragraph 9A.1
computers fitted in an aircraft for use with GPS
navigation computers in an aircraft for use with an RNAV system or GNSS
 Paragraph 9A.2, definitions
AIRAC cycle means the Aeronautical Information Regulation And Control cycle, in accordance with Annex 15, Aeronautical Information Services (AIS), of the Chicago Convention, which documents and defines a series of common dates, and an associated standard aeronautical information publication procedure, for each Convention State.
current, for a navigation database at a particular time, means updated in compliance with the requirements of the AIRAC cycle applying at the particular time.
GNSS means the Global Navigation Satellite System installed in an aircraft to continually compute the position of the aircraft by use of the GPS.
GPS means the Global Positioning System.
IRU or inertial reference unit is a type of inertial sensor which uses gyroscopes and accelerometers to determine a moving aircraft’s rotational attitude and translational position over a period of time.
MEL means an aircraft’s minimum equipment list, as approved by the State of registration of the aircraft.
navigation computer means a computer installed in, or carried on, an aircraft for the principal purpose of navigating, or assisting in the navigation of, the aircraft.
RNAV means a method of navigation which permits an aircraft to operate on any desired flight path within one or both of the following:
(a) the coverage of ground-based or space-based navigation aids;
(b) the limits of the capability of a self-contained navigation system with which the aircraft is equipped.
RNAV system means a navigation system using positioning inputs from GNSS or an inertial reference unit.
State means a nation state that is a signatory to the Chicago Convention.
 Paragraph 9A.3
 Paragraph 9A.4
Subject to paragraph 9A.4A, a navigation
 After paragraph 9A.4
9A.4A The reference in paragraph 9A.4 to currency does not apply to an aircraft (an exempted aircraft):
(a) during flight — if the navigation database expires because it has not been updated for the requirements of a new AIRAC cycle which commenced during the flight; or
(b) for a period of not more than 72 hours from the time the navigation computer database expires — but only if currency is not required under the MEL for the aircraft.
9A.4B If an aircraft’s navigation computer database is to be used for the navigation purposes of an exempted aircraft under paragraph 9A.4A, then:
(a) before each flight, the computer’s database navigation fixes, and the coordinates, frequencies, status (as applicable), and suitability of navigation facilities, required for the intended route must be verified by approved sources of navigation information other than the navigation computer database itself; and
(b) radio navigation aids that are used for departure, arrival and approach procedures must be tuned in to and identified; and
(c) despite paragraph 9A.4A, an RNAV departure, arrival or approach procedure must not be used if it is one that has been changed in the latest AIRAC cycle and the aircraft’s navigation computer database is not current for the change; and
(d) if an aircraft is to commence, or continue, a flight with a navigation computer database that is not current for the AIRAC cycle, the operator or the pilot in command must advise air traffic control before the flight commences, or on first contact during continued flight.
9A.4C For an aircraft:
(a) that is engaged in en route or terminal navigation; and
(b) whose navigation computer database complies with paragraphs 9A.3 and 9A.4; and
(c) that is not an exempted aircraft under paragraph 9A.4A;
each navigation computer database selected track and distance between way points is to be cross-checked for accuracy and reasonableness by reference to:
(d) current en route and area charts; or
(e) the flight plan; or
(f) the navigation log.
 Paragraph 9A.5
 Paragraph 9A.7
 Paragraph 9A.8
 Paragraph 9A.9
 Paragraph 9A.10
 Subsection 9A, renumbering
renumber the provisions mentioned in column A of the following table with the corresponding number in column B of the table
 Subsection 9A
9A.4A (wherever occurring)