REFRESHERS · RULES · 3 MINUTES · AUSTRALIA
Altimeter setting wording updated.
CASA reworded the VFRG's altimeter setting text in August 2024. The rule behind it, in the Part 91 MOS, gives you two choices at or below the transition altitude.
Step 1 of 4
What changed, and when
In version 8.1 of the VFRG, CASA amended its altimeter setting text. CASA says the amendment reflects the unlimited option to use the current forecast area QNH, and improves readability. Sources: VFRG v8.1 history
Limits of this refresher The VFRG says to use 1,013.2 hPa at or above the transition altitude. The MOS rule quoted here sets a QNH at or below it. So exactly at the transition altitude, the two texts differ.
Step 2 of 4
What it means in practice
PREDICT FIRST
Section 11.02 of the Part 91 MOS sets the transition altitude. What altitude does it give?
Skip the question and read on
The transition altitude is 10,000 ft. At or below it, set either a current local QNH from a station along your route within 100 NM of the aircraft, or the current forecast area QNH. Sources: MOS 11.02 (2), MOS 11.02 (5)
The local QNH may be an accurate QNH or a forecast QNH. A station's QNH counts only if the station is along your route and within 100 NM of the aircraft. Sources: MOS 11.02 (5)
You can get a QNH from a reporting station such as an ATIS or AWIS, from a TAF, from the area QNH forecast, or from ATS. Sources: VFRG, altimeter setting
Each chip after a paragraph jumps to the words it rests on.
Step 3 of 4
The source, word for word
Quoted from the Australian sources we hold, with the date we checked them.
Version 8.1 August 2024 | Details Chapter 3 – Flying your aircraft page 218/219 | Changed two bullet points at the top of page 219 to read: If you are flying below the transition altitude, set your altimeter using either: > the current local QNH (either an accurate QNH or forecast QNH) of a station along the route within 100 NM of the aircraft > the current forecast area QNH. Added note: Note: QNH is available from a reporting station (AAIS, ATIS, AWIS, CA/GRS, VOLMET or WATIR), a TAF, the area QNH forecast, or from ATS (ATC or FIS). Amended graphic on page 218 to reflect the amended text. Amendment reflects the unlimited option to use the current forecast area QNH, and improves readability.
If you are flying below the transition altitude, set your altimeter using either: › the current local QNH (either an accurate QNH or forecast QNH) of a station along the route within 100 NM of the aircraft › the current forecast area QNH. Note: QNH is available from a reporting station (AAIS, ATIS, AWIS, CA/GRS, VOLMET or WATIR), a TAF, the area QNH forecast, or from ATS (ATC or FIS). If you are flying at, or above, the transition altitude, you must use an altimeter setting of 1,013.2 hPa.
(2) The transition altitude is 10 000 ft.
(5) For an operation at or below the transition altitude, an aircraft’s altimeter setting must be: (a) the current local QNH (either an accurate QNH as defined in section 10.06 or a forecast QNH) of a station along the route within 100 NM of the aircraft; or (b) the current forecast area QNH.
Step 4 of 4
Practise this
1 question from our bank test this change. Each one quotes the rule it rests on, and the ones you miss come back sooner.
That is all we ask on this change so far. New questions are added only after they pass a source check and an independent review.
SOURCES FOR THIS REFRESHER
- CASA Visual Flight Rules Guide v8.3 (CC BY-NC 4.0), Version history, version 8.1 (August 2024)
- CASA Visual Flight Rules Guide v8.3 (CC BY-NC 4.0), Transition altitude, transition layer and transition level (CASR 91 MOS 11.02)
- Part 91 (General Operating and Flight Rules) Manual of Standards 2020, Compilation No. 8, Subsection 11.02 (2)
- Part 91 (General Operating and Flight Rules) Manual of Standards 2020, Compilation No. 8, Subsection 11.02 (5)
Practice questions: Source-checked, awaiting pilot review. Learning only. Your instructor and the current rules come first. Sources and licences