Document ID: chunk:federal_register_of_legislation:F2025C00187:reg:4:p5
Version: federal_register_of_legislation:F2025C00187
Segment Type: reg
Provision Reference: reg 4 (pt 5/6)
Character Range: 147549–150026

ft — the pilot in command may conduct a flight to the first point of landing where the accuracy of the second system can be rechecked; and
(c) if, on rechecking, the second system shows an error in excess of 60 ft — the pilot in command must consider the second system to be inoperative for further IFR flight.
       (3) If 1 pressure altitude system is required for the category of operation, but 2 are fitted, then:
(a) the pilot in command is permitted to conduct a flight if at least 1 system (the first system) reads the site elevation to within 60 ft; and
(b) if the other system (the second system) has an error in excess of 75 ft — the pilot in command must consider the second system to be inoperative for further IFR flight.
       (4) If 1 pressure altitude system is required for the category of operation, and 1 is fitted, then:
(a) if the system has an error between 60 ft and 75 ft — the pilot in command is permitted to conduct a flight to the first point of landing where the accuracy of the system can be rechecked; and
(b) if, on rechecking, the system shows an error in excess of 60 ft — the pilot in command must consider the system to be inoperative for further IFR flight.

10.05 Checking pressure altitude systems — VFR flight
       (1) A pressure altitude system with an accurate QNH is operative for a VFR flight only if the system reads site elevation to within:
(a) 100 ft; or
(b) at test sites above 3 300 ft — 110 ft.
      (2) If an aircraft that is fitted with 2 pressure altitude systems continues to conduct a flight under the VFR with 1 of the systems erroneously reading more than 100 ft (or 110 ft as the case may be), the pilot in command must consider the erroneous system to be inoperative for further VFR flight.
       (3) For an aeroplane operation conducted under the VFR involving flight above FL 200, the pressure altitude system used must be checked against the accuracy requirements for such system usage under the IFR.

10.06 Accurate QNH and site elevation
       (1) In this Chapter, a QNH is to be considered accurate only if it is provided by 1 of the following:
(a) AAIS;
(b) ATC;
(c) ATIS;
(d) AWIS;
(e) CA/GRS;
(f) WATIR.
       (2) QNH contained in an authorised weather forecast must not be used for checking the accuracy of a pressure altitude system.
       (3) Site elevation must be derived from aerodrome survey data that is:
(a) authorised in writing (as the case requires):
 (i) by CASA; or
 (ii) by an NAA; or