VHHH (香港) 既 transition altitude 同 transition level 係咩?

Reference: ENR 1.7 ALTIMETER SETTING PROCEDURES

1.2 The transition altitude (TA) is 9 000 ft.
1.3 The transition level is FL110.

下面一堆字既小總結:

1. 除左好特殊情況, 離港既過左 TA climb 就轉1013.2 ; 到港既過左FL110 descent 緊就轉QNH
2. 任何時間不應該在TA 到 FL120 呢個layer 到cruise –  一係climb, 一係descent!

Note:
i) When the QNH value at Hong Kong International Airport is 979 hPa or below ATC will inform pilots of the transition level by Arrival ATIS broadcast or voice communication.
ii) The lowest QNH value recorded by the Hong Kong Observatory to date is 953.2 hPa

(Wanda sets the record. As the eye of Wanda passed over the territory, the barometer plunged to the all-time low of 953.2 hPa on 1 September 1962.)

Also ref: Tropical Cyclones necessitating the issuing of the Hurricane Signal No.10 ｜Hong Kong Observatory(HKO)｜Tropical Cyclone

Transition altitude: the altitude at or below which the vertical position of an aircraft is controlled by reference to altitudes.
Transition layer: the airspace between the transition altitude and the transition level.
Transition level : the lowest flight level available for use above the transition altitude.

2 Basic Altimeter Setting Procedures
2.1 Procedures
2.1.1 Aircraft operating beyond a range of 50 NM from Hong Kong International Airport, AND those within 50 NM of the airport but at or above the transition level will use an altimeter setting of 1013.2 hPa.
2.1.2 Aircraft operating within 50 NM of Hong Kong International Airport at or below the transition altitude (9 000 ft) will use the local QNH setting supplied by ATC.
2.1.3 Aircraft wishing to operate within 50 NM of Hong Kong International Airport shall not flight plan to cruise at levels between the transition altitude and FL120.

2.2 Change of Settings

到港既 (Arriving)

2.2.1 Arriving aircraft at Hong Kong International Airport will change from an altimeter setting of 1013.2 hPa to the local QNH setting :-

• a) When 50 NM from the airport, if at or below the transition altitude (9 000 ft), or
• b) When vacating the transition level on a descent, if within 50 NM of the airport.

Note: Aircraft approaching at or below 9 000 ft may be instructed by ATC to use the local QNH setting before reaching 50 NM from the airport, if it is considered necessary in the interest of flight safety.

離港既 (Departing)

2.2.2 Departing aircraft from Hong Kong International Airport will change from the local QNH setting to an altimeter setting of 1013.2 hPa:
a) When 50 NM from the airport, if at or below the transition altitude (9 000 ft).
b) When vacating the transition altitude on a climb, if within 50 NM from the airport.