GEN 3.5  METEOROLOGICAL SERVICES

1  Responsible Meteorological Offices

1.1 The Meteorological Authority designated in accordance with ICAO Annex 3 para. 2.1.4 to provide the meteorological facilities and services for international air navigation covered by this AIP is the Hong Kong Observatory (HKO), a department of the Hong Kong Special Administrative Region Government, with its headquarters at Tsim Sha Tsui, Kowloon.
1.2 The Hong Kong Observatory operates an Airport Meteorological Office (AMO)1 at the Hong Kong International Airport (HKIA). Located at Level T3 of the South Aerodrome Control Tower (S-TWR), the South AMO (S-AMO) together with the Ancillary AMO (A-AMO) located at Level T2 of the North Aerodrome Control Tower (N-TWR), and the North AMO (N-AMO) at Level T2 of the New Air Traffic Control Tower (NAT) forms a resilient group of offices to provide aeronautical meteorological services. Weather observation and reporting, provision of forecast and warnings are undertaken by qualified aeronautical meteorological personnel meeting World Meteorological Organization (WMO) qualification, competencies, education and training standards.

Note

  1. When references are made to the Airport Meteorological Office (AMO) without mentioning the location, it refers to one or more of the three offices (S-AMO, A-AMO and N-AMO) depending on the activation status of the offices.
1.3 The service is provided in accordance with the provisions contained in the following ICAO documents

Differences from these provisions are detailed in GEN 1.7.

2  Area of Responsibility

2.1 The AMO serves as the meteorological watch office and maintains meteorological watch for the Hong Kong FIR and issues SIGMET information in respect of the occurrence or expected occurrence of specified en-route weather and other phenomena in the atmosphere which necessitate the issue of SIGMETs. The AMO also serves as the aerodrome meteorological office and aeronautical meteorological station for HKIA.

3  Meteorological Observations and Reports

3.1 Weather Observers are on duty H24 at the AMO to make routine meteorological observations and to issue reports at half-hourly intervals. Reports of routine observations are issued as local routine report for dissemination at the aerodrome and as METAR for dissemination beyond the aerodrome.
3.2 The Weather Observer also makes special meteorological observations and issue reports whenever changes meet any of the criteria specified in ICAO Annex 3, Appendix 3, Section 2.3 and when the crosswind components change through 20 kt. Reports of special observations are issued as local special report for dissemination at the aerodrome and as SPECI for dissemination beyond the aerodrome. The same set of criteria is adopted for the issuance of local special report and SPECI for mean surface direction, mean surface wind speed, variation from the mean surface wind speed (gusts), prevailing visibility, runway visual range, onset/cessation/change in intensity of weather phenomena, height of base of the lowest cloud layer, and amount of cloud layer below 1 500 ft. The detailed criteria for the issuance of local special report and SPECI are provided on the Aviation Meteorological Information Dissemination System (AMIDS) (see para. 10). 
3.3 The observing systems and sites, and operating procedures are described in more details in para. 3.6 and 4 below.

Table GEN 3.5.3 Meteorological Observations and Reports

Name of Station/Location Indicator Type and Frequency of Observations Type of MET Reports & Supplementary Information Included Observation System and Sites Hours of Operation Climatological Information
1 2 3 4 5 6
HONG KONG/ INTERNATIONAL

VHHH		 Half hourly plus special observations MET Report / Special Report Trend, Wind Shear Cup anemometers, RVR transmissometers and forward scatterers
(see chart page AD 2-VHHH-ADC-1).

See para. 3.6 below for sites of TDWRs, WTWS anemometers, weather buoys and wind profilers, Doppler LIDARs, short-range LIDAR, RVR transmissometers, forward scatterers and ceilometers.		 H24 Climatological tables AVBL
3.4 Owing to the variability of meteorological elements in space and time, limitations of observing techniques and limitations caused by the definitions of some of the elements, the specific value of any of the elements given in a report shall be understood to be the best approximation to the actual conditions at the time of the observation.
3.5 In local routine reports, present weather information is representative of conditions at the aerodrome, i.e. within a radius of approximately 8 km of the aerodrome reference point. In METAR, present weather information is representative of conditions at the aerodrome and, for certain specified weather phenomena, in its vicinity, i.e. the area that lies within a radius of approximately 8 km and 16 km of the aerodrome reference point.
3.6 Locations of the Terminal Doppler Weather Radars (TDWR), Windshear and Turbulence Warning System (WTWS) anemometers, weather buoys and wind profilers, Doppler LIDARs, short-range LIDARs, Runway Visual Range (RVR) transmissometers, forward scatterers and ceilometers are shown in GEN 3.5-HKO-EQ.

4  Observing Systems and Operating Procedures

4.1 ANEMOMETERS
4.1.1 Three sets of anemometers are installed near each of the three runways, i.e. the south runway (RWY 07R TDZ, RWY 07R/25L MID RWY and RWY 25L TDZ), the centre runway (RWY 07C TDZ, RWY 07C/25C MID RWY and RWY 25C TDZ), and the north runway (RWY 07L TDZ, RWY 07L/25R MID RWY and RWY 25R TDZ). Reports of observations made at the AMO from the records of the anemometer near RWY 07L/25R MID RWY constitute the official wind reports. Winds in aerodrome forecasts for the airport refer to this location.
4.1.2 In the event that records of the anemometer near RWY 07L/25R MID RWY are not available, wind information at RWY 25R TDZ, RWY 07L TDZ, RWY 25L TDZ, RWY 07R TDZ or RWY 07R/25L MID RWY, in that order, will be substituted.
4.2 CEILOMETERS
4.2.1 Cloud base is measured by ceilometers installed near the runway thresholds of RWY 07L, RWY 07C, RWY 07R, RWY 25L, RWY 25C and RWY 25R, and at Siu Mo To and Meteorological Garden adjacent to S-TWR.
4.3 RUNWAY VISUAL RANGE (RVR) AND VISIBILITY
4.3.1 Nine sets of transmissometers and forward scatterers are installed for observation of RVR and visibility along the runways. 
4.3.2 Whenever the RVR value and/or the visibility is observed to be less than 1 500 m, the RVR values observed at the thresholds are included in MET reports. These will be disseminated beyond the airport and used for meteorological broadcast (VOLMET) and for display to ATC as appropriate.
4.3.3 RVR values will be reported in the following scale:-
  1. from 50 m up to 400 m at increments of 25 m;
  2. from 400 m up to 800 m at increments of 50 m;
  3. from 800 m up to 1 500 m at increments of 100 m.
Note: Values between scale points are rounded down to the nearest lower scale point.
4.3.4 RVR values are updated every 10 seconds and averaged over a period of 60 seconds. 
4.3.5 RVR reports should be used by pilots in comparison with their weather minima. RVR values will be passed to aircraft whenever the reading is less than 1 500 m at the commencement of each approach for landing and before every take-off. Subsequent changes will also be passed.
4.3.6 When all three positions are reported, the values will be passed as three numbers relating to touchdown, mid-point and stop-end respectively, e.g. RVR 650, 600, 500. When only two values are reported, (touchdown and only one of the successive positions), the latter value will be prefixed with its position, e.g. RVR 650, stop-end 500 or RVR 650, mid-point 600.
4.3.7 Values in excess of 1 500 m will not be given, controllers shall report that the RVR as more than 1 500 m.
4.3.8 ATC will be notified by AMO of changes in serviceability status of the transmissometers. ATC will then inform pilots and notify the AIMC to issue a NOTAM.
4.4 TEMPERATURE AND PRESSURE
4.4.1 Digital thermometers are used to measure air temperature and wet-bulb temperature, and are installed in Meteorological Garden adjacent to S-TWR.
4.4.2 Digital barometers are used to measure atmospheric pressure, and are installed in Meteorological Garden adjacent to S-TWR.
4.5 WIND SHEAR AND TURBULENCE ALERTING SERVICE
4.5.1 The Wind Shear and Turbulence Warning System (WTWS) (see para. 5) continuously monitors low-level wind shear and turbulence within 3 NM of each runway threshold and over the runway to automatically provide concise alerts to ATC. The system will, however, not generate alerts out of 2 NM over the departure corridors except microburst alerts. An alert of wind shear, microburst and turbulence generated by WTWS over the runway or within 3 NM of touchdown is passed by ATC to landing aircraft. An alert of wind shear and turbulence generated by WTWS over the runway or within 2 NM over the departure corridor as well as microburst over the runway or within 3 NM over the departure corridor is passed by ATC to aircraft prior to departure.
4.5.2 The types of alerts provided by WTWS and passed by ATC are:
  1. Microburst Alert – when RWY orientated wind speed loss is 30 kt or greater and accompanied by precipitation,
  2. Wind Shear Alert – when RWY orientated wind speed gain is 15 kt or greater, or RWY oriented wind speed loss is between 15 kt and 29 kt, or RWY oriented wind speed loss is 30 kt or greater and not accompanied by precipitation,
  3. Turbulence Alert – when turbulence is of a moderate or severe intensity (as expected to be experienced by a HEAVY category aircraft).
4.5.3 A warning of wind shear and turbulence issued by AMO in respect of observed or expected occurrence of wind shear and turbulence below 1 600 ft on final approach or on departure is provided on Voice-ATIS and D-ATIS (see para. 7). In issuing the warning, AMO makes reference to weather sensors including: Terminal Doppler Weather Radar (TDWR), Doppler Light Detection and Ranging (LIDAR) systems and an extensive anemometer network on and in the vicinity of the airport, weather buoys as well as pilots’ reports.

5  Wind Shear and Turbulence Warning System (WTWS)

5.1 GENERAL 
5.1.1 WTWS processes and integrates data from weather sensors including the TDWR, LIDARs and an extensive anemometer network on and in the vicinity of the airport and weather buoys to detect wind shear and turbulence and generate alerts. The update rate of alerts is at least once every minute.
5.1.2 Wind shear and turbulence events can be of very small scale, sporadic and transient in nature and may affect successive aircraft differently. This is especially so when winds change rapidly, e.g. when winds blow across terrain and possibly buildings, especially during the passage of a tropical cyclone. As such, wind shear and turbulence experienced by an aircraft may at times differ from the alerts provided and from the conditions reported by preceding aircraft.
5.1.3 A Microburst Alert will be generated when TDWR indicates that RWY orientated wind speed loss is 30 kt or greater and accompanied by precipitation. The wind shear associated with this Microburst Alert may be caused by phenomena other than convection, e.g. terrain-induced wind disturbances. Microbursts may be asymmetric, having winds on one side stronger than the other. The column of downdraft from the microburst can hit the ground at an angle rather than vertically. Therefore, the sequence of events in traversing a microburst in the conventional sense (a gain of headwind followed by a downdraft and a loss of headwind) should not be expected to always occur when a Microburst Alert is in effect. 
5.1.4 When a Microburst Alert or Wind Shear Alert is in effect, particularly with wind speed gains or losses of 30 kt or greater, pilots are strongly advised to avoid entering the alert area.
5.1.5 Detailed information on the WTWS can be obtained from the HKO/IFALPA/The Honourable Company of Air Pilots booklet ‘Windshear and Turbulence in Hong Kong - Information for Pilots’. This may be viewed at the HKO website:
http://www.weather.gov.hk/en/aviat/articles/files/booklet_latest_edition.pdf
5.2 MICROBURST / WIND SHEAR ALERTS
5.2.1 The Microburst or Wind Shear Alert passed by ATC includes the type of alert (i.e. microburst or wind shear), the magnitude of the runway orientated wind speed difference and the location (final approach, departure or runway area as appropriate).
5.2.2 When more than one occurrence of wind shear is detected for a particular runway corridor, WTWS provides a consolidated Microburst or Wind Shear Alert for that particular runway corridor based on a priority system which takes into consideration the severity of the alerts and the confidence level of the different data sources which generate the alerts.
E.g. If a microburst with an intensity of minus 30 kt and a wind shear with an intensity of plus 15 kt are detected, only a Microburst Alert will be issued.
5.2.3 Detailed information on the priority system used when providing WTWS alerts can be obtained from the booklet and website given in para 5.1.5 above.
5.2.4 Gain and loss events can co-exist within the same runway corridor, particularly for terrain-induced wind shear. The WTWS is designed to assign a higher priority to a Wind Shear Alert of wind loss than a Wind Shear Alert of wind gain. If the former is issued, pilots are reminded that they may still encounter wind gain events.
5.3 TURBULENCE ALERTS
5.3.1 The Turbulence Alert passed by ATC includes the intensity and type of alert (i.e. moderate or severe turbulence), and the location (final approach, departure or runway area as appropriate). Severe turbulence will be alerted when the peak value of the cubic root of the eddy dissipation rate (EDR) equals or exceeds 0.5. The corresponding threshold for alerting moderate turbulence is 0.3.
5.4 MICROBURST / WIND SHEAR ALERT COMBINED WITH TURBULENCE ALERT
5.4.1 When a Microburst Alert or a Wind Shear Alert is given for a particular runway corridor and turbulence is also detected for that particular runway corridor, a Turbulence Alert will be passed by ATC together with the Microburst Alert or Wind Shear Alert.

6  Phraseology of Alerts Passed by ATC 

6.1 Alerts generated by the WTWS will be passed by ATC and preceded by the word ‘caution’. Examples of the phraseology used by ATC to pass wind shear and turbulence alerts are:
  1. ‘(call sign) caution microburst minus 30 kt on final approach’;
  2. ‘(call sign) caution wind shear plus 25 kt on departure’;
  3. ‘(call sign) caution wind shear plus 15 kt on the runway’;
  4. ‘(call sign) caution severe turbulence on final approach’;
  5. ‘(call sign) caution wind shear plus 20 kt and moderate turbulence on departure’.

7  Wind Shear and Turbulence Warnings on ATIS

7.1 Wind shear and turbulence warnings are given immediately after the runway-in-use at the beginning of the Voice-ATIS and D-ATIS.
7.2 The Arrival and Departure ATIS wind shear and turbulence warnings will be given as either ‘forecast’ when the information is predicted by the Aviation Meteorological Forecaster, or ‘forecast and reported’ when the information has been confirmed by pilot reports in the previous 30 minutes. When microburst is detected by the TDWR, a microburst and significant wind shear warning will be given on both the Arrival and Departure ATIS without indicating ‘forecast’ or ‘forecast and reported’. 
7.3 Wind shear and/or turbulence warnings may include the specific runway corridor(s) to which the information is applicable or  to all runway corridors. Examples of wind shear and turbulence warnings on Arrival and Departure ATIS are:
  1. Microburst and significant wind shear 07L and 07R;
  2. Significant wind shear forecast 07R;
  3. Significant wind shear forecast and reported 07L and 07R;
  4. Moderate turbulence forecast 25L and 25R;
  5. Moderate turbulence forecast and reported 25L and 25R.

(ICAO abbreviations, e.g. ‘MBST AND SIG WS’, ‘SIG WS FCST’ and ‘MOD TURB FCST AND REP’ are used for D-ATIS.)

7.4 As cumulonimbus (CB) is already reported on ATIS and it is commonly understood that turbulence may occur near CB, warning of turbulence in the vicinity of CB is not provided.

8  Pilot Reports of Wind Shear and Turbulence

8.1 For the benefit of subsequent aircraft and for validation and further enhancement of the low-level wind shear and turbulence alerting services, pilots are requested to inform ATC if they experience any microburst, wind shear or turbulence on arrival or departure, irrespective of whether an alert has been given. ATC will pass such reports to following aircraft.
8.2 Pilots may contact HKO via email to amo@hko.gov.hk to provide more detailed information about microburst, wind shear and turbulence encounters with reference to the template form available at the HKO website:
http://www.weather.gov.hk/aviat/amt_e/report_form.pdf

9  Additional Meteorological Information in ATIS Broadcasts

9.1 HILLTOP WINDS
9.1.1 To assist pilots in assessing possible wind changes that may be experienced during the final phase of approach under strong wind conditions, when the 2 minute mean wind measured at approximately 2 500 ft AMSL on Yi Tung Shan (primary) or Nei Lak Shan (backup) exceeds 35 kt, it will be given at the end of the Arrival ATIS (see GEN 3.5-HKO-EQ for the location of these anemometers.)
e.g. ‘2500 FT ESTIMATED WIND 160 DEG 40 KT’
9.1.2 Due to spatial variability of the wind and different geographical environment of the hilltop stations, the hilltop wind data may be different from the wind actually experienced by aircraft at 2 500 ft on the approach track.
9.2 PREVAILING VISIBILITY
9.2.1 Prevailing visibility is included in METAR/SPECI as described in Note 1) of para 13.1. To provide pilots with an overall picture of visibility, when any one of the nine RVR values is lower than 1 500 m or the prevailing visibility is lower than 3 000 m, the prevailing visibility will also be given on ATIS.
9.3 THUNDERSTORM ACTIVITY
9.3.1 Information on thunderstorm activities due to significant convection which are affecting or expected to affect the approach, departure or missed approach areas in one hour’s time will be included in the ATIS broadcast. The Arrival ATIS will give information relevant to the approach and missed approach areas and the Departure ATIS will give information relevant to the departure areas. 
9.3.2 The information will include the approximate distance and bearing from the airport, and the direction of movement, if possible.
e.g. ‘Thunderstorm 20 NM southwest moving northeast’.
e.g. ‘Widespread thunderstorm 20 NM northeast moving southeast.’
9.3.3 Considering the dynamic nature of convection, distance, bearing and/or movement information may be omitted.
e.g. ‘Thunderstorm to northwest moving southeast’.
e.g. ‘Scattered thunderstorm within 20 NM moving east.’
e.g. ‘Widespread thunderstorm within 20 NM.’
9.3.4 Time of occurrence of thunderstorms may be indicated if available.
e.g. ‘Thunderstorm from 0330 to 0430’.
9.4 SIGNIFICANT TAILWIND ON BASE LEG 
9.4.1 Unexpected significant tailwind on base leg can affect the descent profile of aircraft. This is particularly relevant to runway 07 operations because of the restricted airspace for base leg and short final approach which may result in a destabilised approach. When the reported tailwind on runway 07 base leg is 20 knots or greater, but is not anticipated from the surface wind velocity, the information will be included in the Arrival ATIS.
e.g. ‘Expect significant tailwind on base leg’.

10  Types of Services

10.1 GENERAL INFORMATION
10.1.1 Two  Aviation Forecasters are on duty H24 at the AMO to prepare weather forecasts, issue warning messages and provide weather briefings on weather impacting air traffic. Aerodrome forecasts (TAF) valid for 30 hours are issued every 3 hours. The 30-hour TAF includes forecast of the maximum and minimum temperatures within the validity period. A forecast valid for 9 to 12 hours is extracted from the 30-hour TAF for inclusion in the scheduled VOLMET broadcasts and D-VOLMET (see Table GEN 3.5.13 VOLMET Service). Landing forecast is issued in the form of a trend forecast appended to MET reports, and is updated with the issuance of MET reports.
10.1.2 The issue of a new forecast shall be understood to automatically supersede any forecast of the same type previously issued.
10.1.3 Telephone consultation can also be obtained from the following sources:
10.1.4 The latest meteorological information is displayed and made available to flight crew members and operators for self-briefing, flight planning and flight documentation purposes via the Aviation Meteorological Information Dissemination System (AMIDS), including,
  1. forecasts of
    1. upper wind and upper-air temperature;
    2. flight level and temperature of tropopause;
    3. direction, speed and flight level of maximum wind; and
    4. SIGWX phenomena;
  2. METAR or SPECI (including trend forecasts as issued in accordance with regional air navigation agreement) for the aerodromes of departure and intended landing, and for take-off, en-route and destination alternate aerodromes;
  3. TAF or amended TAF for the aerodromes of departure and intended landing, and for take-off, en-route and destination alternate aerodromes;
  4. forecasts for take-off;
  5. SIGMET information and appropriate special air-reports, relevant to the whole route;
  6. volcanic ash and tropical cyclone advisory information relevant to the whole route;
  7. aerodrome warnings for HKIA;
  8. meteorological satellite images;
  9. ground-based weather radar information; and
  10. space weather advisory information relevant to the whole route. 
10.1.5 For aircraft take-off and landing, aerodrome forecast and actual reports are disseminated to ATC for onward transmission to pilots and operators.
10.1.6 Owing to the variability of meteorological elements in space and time, limitations of forecasting techniques and limitations caused by the definitions of some of the elements, the specific value of any of the elements given in a forecast shall be understood by the recipient to be the most probable value which the element is likely to assume during the period of the forecast. Similarly, when the time of occurrence or change of an element is given in a forecast, this time shall be understood to be the most probable time.
10.1.7 Forecasts of weather phenomena in TAF and landing forecast are for the area at the aerodrome, within a radius of approximately 8 km of the aerodrome reference point. Forecasts of cloud are for the aerodrome and its vicinity, i.e. the area within a radius of approximately 16 km of the aerodrome reference point.
10.2 INFORMATION FOR OPERATORS FOR PRE-FLIGHT PLANNING AND FOR IN-FLIGHT RE-PLANNING 
10.2.1  Information for pre-flight planning such as copies of the latest prognostic significant weather chart, forecast upper wind and upper-air temperature charts for standard flight levels, flight level of tropopause, direction, speed and flight level of maximum wind and selected meteorological information can be obtained by operators via AMIDS no later than three hours prior to departure. Forecast for take-off within the next three hours is available on the AMIDS and is also provided upon request.
10.2.2 Flight documentation for each flight is made available on the AMIDS two hours before its departure and is updated as new information is received. Messages will pop up on the AMIDS whenever the weather conditions included in the flight documentation differ materially from that already made available earlier. Operators are advised to retrieve the flight documentation two hours before departure of the flight and then retrieve updated information closer to the departure time.
10.2.3 Information, including METAR/SPECI and TAF for selected aerodromes and SIGMET and volcanic ash and tropical cyclone advisory information as well as those listed in para 10.2.1 may be obtained at any time via AMIDS and upon request for in-flight re-planning by operators.
10.3 INFORMATION FOR USE BY FLIGHT CREW BEFORE DEPARTURE FROM HONG KONG
10.3.1 Flight documentation for all flights leaving Hong Kong is made available on the AMIDS two hours before departure. On request, flight documentation can also be sent by fax. Pre-departure amendment to flight documentation and aerodrome forecasts supplied as part of the flight documentation will be made available normally by pop up messages on AMIDS.
10.3.2 The documentation normally contains a selection of fixed time prognostic charts of significant weather and upper wind and upper-air temperature data appropriate to the cruising level (normally one or more of FL180, FL300, FL340 and FL390 charts), METAR/SPECI, aerodrome forecasts, SIGMETs and special air-reports, volcanic ash and tropical cyclone advisory information from the information specified in para. 10.1.4 a) i) and iv), b), c), e) and f), covering the flight concerned in respect of time, altitude and geographical extent. In general, the information provided relates to appropriate fixed times, or periods of time, and extends to the aerodrome of intended landing, also covering the meteorological conditions expected between the aerodrome of intended landing and alternate aerodromes designated by the operator.
10.3.3 For long haul flights, one or more High Level Significant Weather (SWH) prognostic chart(s) and Wind/Temp chart(s) from World Area Forecast Centres (WAFCs) are supplied to high level flights. A Medium Level Significant Weather (SWM) prognostic chart from the AMO plus Wind/Temp prognostic chart(s) from WAFCs appropriate to the cruising level are supplied to medium level flights. A SWM prognostic chart from the AMO plus one or more SWM prognostic charts from WAFCs, if necessary, are also supplied to EDTO flights.
10.3.4 Aerodrome forecasts from other meteorological offices and forecast charts from WAFCs are normally included in flight documentation without modification.
10.3.5 In order to obtain the latest information including those from the meteorological satellites and weather radars, flight crews are advised to make use of the AMIDS or consult the Aviation Forecaster by telephone before departure.
10.3.6 In case of prolonged failure of the AMIDS, flight documentation and other meteorological information may be made available via fax to the operators. The operators will be advised by fax when the above arrangement is activated.
10.3.7 Information supplied to flight crew members are retained for a period of at least 30 days from the date of issue. This information is available on request, for inquiries or investigations and, for these purposes, shall be retained until the inquiry or investigation is completed.
10.4 INFORMATION FOR AIRCRAFT IN FLIGHT
10.4.1 Meteorological reports issued by the AMO together with those received from a selection of neighbouring aerodromes are disseminated by means of scheduled VOLMET broadcasts or D-VOLMET (see Table GEN 3.5.13 VOLMET Service). Additional meteorological information will be issued to the pilot-in-command on request (see also VHHH AD 2.18 for information on ATIS Broadcast).
10.5 INFORMATION TO AIR TRAFFIC SERVICES UNITS
10.5.1 Routine, special and extra MET reports, trend-type landing forecasts, aerodrome forecasts, SIGMET information, wind shear and turbulence alerts, aerodrome warnings, assessment on significant convection affecting air traffic, weather briefings and other relevant supplementary information are provided to the air traffic services units.
10.5.2 Displays related to data from the equipment listed under para. 4 above are also provided to Air Traffic Services in real-time to support approach, landing and take-off operation.
10.5.3 Provision of meteorological services to the Air Traffic Services (ATS) units and coordination arrangements between the Meteorological Authority and the ATS Authority are documented in the “Agreed Coordination Arrangements between the Hong Kong Observatory and Hong Kong Civil Aviation Department in Respect of the Provision of Meteorological Service for International Air Navigation”, as per the guidelines in ICAO Doc 9377 “Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services”.
10.6 INFORMATION FOR SEARCH AND RESCUE SERVICES UNITS
10.6.1 The AMO maintains liaison with the search and rescue services units and supplies all the meteorological information to the Rescue Co-ordination Centre as and when required.

11  Notification Required from Operators

11.1 Operators requiring meteorological service or changes in existing meteorological service shall notify, sufficiently in advance, the HKO or the AMO in accordance with ICAO Annex 3, para. 2.3.
11.2 Operators requiring meteorological service shall notify the HKO and shall supply all details necessary for the planning of appropriate arrangements by HKO, at least one month in advance, when:
  1. new routes or new types of operations are planned;
  2. changes of a lasting character are to be made in scheduled operations;
  3. other changes, affecting the provision of meteorological service, are planned.
11.3 Operators or their flight crew members shall notify the AMO, as soon as the following information becomes available :
  1. change of flight schedules;
  2. when non-scheduled flights are to be operated; and
  3. when flights are delayed, advanced or cancelled.

Unless otherwise notified, AMO will utilize the information available on the Airport Operational Database (AODB) operated by the Airport Authority Hong Kong.

12  Aircraft Reports

12.1 SPECIAL AND OTHER NON-ROUTINE AIRCRAFT REPORTS
12.1.1 Further to the pilot reporting of low-level wind shear and turbulence at HKIA (see Section 8 above), pilots are requested to pass special aircraft observations as soon as possible to the appropriate ATS unit by voice communications whenever any of the following conditions are encountered or observed:

moderate or severe turbulence;
moderate or severe icing;
severe mountain wave;
thunderstorms, without hail (obscured, embedded, widespread or in squall lines);
thunderstorms, with hail (obscured, embedded, widespread or in squall lines);
heavy dust storm or heavy sandstorm;
volcanic ash cloud;
pre-eruption volcanic activity or a volcanic eruption.
12.1.2 When other meteorological conditions not listed under 12.1.1 are encountered and which, in the opinion of the pilot-in-command, may affect the safety or markedly affect the efficiency of other aircraft operations, the pilot-in-command shall advise the ATC as soon as practicable.
12.1.3 For flights operating on routes which could be affected by volcanic ash clouds, pilots are also requested to record special aircraft observations of pre-eruption volcanic activity, a volcanic eruption or volcanic ash cloud, on the special air-report of volcanic activity form (Ref ICAO PANS-ATM (Doc 4444) Appendix 1), which is supplied with the flight documentation for routes which could be affected by volcanic ash clouds, and send the completed form to the aerodrome meteorological office without delay upon arrival at an aerodrome. This form is also available at the HKO website
http://www.weather.gov.hk/aviat/amt_e/vareport.pdf
12.1.4 Aircraft observations shall be reported as air-reports following the instructions in ICAO PANS-ATM (Doc 4444) Appendix 1.

13  VOLMET Service

13.1 VOLMET broadcast in English on designated HF and VHF channels is available on regular schedules throughout the day. D-VOLMET is also available to suitably equipped aircraft. Details of these meteorological broadcasts are given in the following table:

Table GEN 3.5.13 VOLMET Service

Name of Station CALL SIGN Identification (EM) Frequency Broadcast Period
(UTC)		 Hours of Service Aerodromes Included Contents & format of REP and FCST & Remarks
1 2 3 4 5 6 7
Hong Kong Hong Kong VOLMET 128.875 MHZ Continuous H24 ZGSZ Shenzhen METAR/SPECI
VMMC
Macao		 METAR/SPECI & Trend FCST
RCTP
Taibei		 METAR/SPECI & Trend FCST
RCKH
Gaoxiong		 METAR/SPECI & Trend FCST
Hong Kong Hong Kong VOLMET D-VOLMET
(See Note 3))		 As requested H24 VHHH
HONG KONG/ INTERNATIONAL		 HKG SIGMET (if any)
Hong Kong Hong Kong VOLMET 6679 KHZ
8828 KHZ
13282 KHZ		 H+15 to H+20
and
H+45 to H+50		 H24 VHHH
HONG KONG/ INTERNATIONAL
(See Note 1) and 2))		 METAR/SPECI & Trend FCST
ZGGG
Guangzhou/Baiyun		 METAR/SPECI & Trend FCST
ROAH
Naha		 METAR/SPECI
RCTP
Taibei International		 METAR/SPECI & Trend FCST
RCKH
Gaoxiong		 METAR/SPECI & Trend FCST
RPLL
Manila International		 METAR/SPECI & Trend FCST
RPVM
Mactan		 METAR/SPECI & Trend FCST
VHHH
HONG KONG/ INTERNATIONAL		 FCST / Amend FCST 

Notes

  1. VHHH METAR/SPECI and Forecasts, wind information refers to the mid anemometer of RWY 07L/25R and the visibility refers to the prevailing visibility observed by the Weather Observer at one or more of the locations including S-AMO at Level T3 of S-TWR, A-AMO at Level T2 of N-TWR, and N-AMO at Level T2 of NAT or at the ground level of the respective offices when deemed necessary, making reference to the measurements of the nine forward scatterers along the north, centre and south runways. 
  2. All METAR/SPECI are the latest available, however, if the latest available METAR/SPECI would be more than two hours old at broadcast time, it is not transmitted.
  3. Special air-reports not covered by a SIGMET will be included as the last item in the D-VOLMET.

14  SIGMET and Aerodrome Warning Services

14.1 GENERAL
14.1.1 For the safety of air traffic, the AMO serves as the meteorological watch office and provides round the clock meteorological watch service for the Hong Kong FIR. This service consists of a continuous weather watch within the Hong Kong FIR and the issuance of SIGMET information for this area.
14.1.2 The AMO also provides an aerodrome warning service for the Hong Kong International Airport (HKIA). This service provides aerodrome warnings giving concise information of meteorological conditions which could adversely affect aircraft on the ground, including parked aircraft, and the aerodrome facilities and services at HKIA.

Table GEN 3.5.14 SIGMET Service

Name of MWO/Location Indicator Hours FIR served Type of SIGMET/Validity Specific Procedures ATS Unit Served Additional Information
1 2 3 4 5 6 7
Hong Kong / VHHH H24 Hong Kong FIR SIGMET / up to 6 hours Tropical Cyclone SIGMET valid for up to 6 hours

Volcanic ash SIGMET valid for up to 6 hours

See also para 14.2.1 and 14.2.2		 Hong Kong ACC and RCC Nil 
14.2 METEOROLOGICAL WATCH SERVICE
14.2.1 As the meteorological watch office for the Hong Kong FIR, the AMO issues SIGMET information concerning the occurrence and/or expected occurrence of specified en-route weather and other phenomena in the atmosphere, which may affect the safety of aircraft operations, and of the development of those phenomena in time and space, in the Hong Kong FIR. The specified en-route weather and other phenomena in the atmosphere are as follows:
  1. Obscured thunderstorms with/without hail
  2. Embedded thunderstorms with/without hail
  3. Frequent thunderstorms with/without hail
  4. Squall line with/without hail
  5. Tropical cyclone with 10-minute mean surface wind speed of 34 kt or more
  6. Severe turbulence
  7. Severe icing
  8. Severe icing due to freezing rain
  9. Severe mountain wave
  10. Heavy sandstorm
  11. Heavy duststorm
  12. Volcanic ash
  13. Radioactive cloud
14.2.2 Volcanic ash SIGMET messages issued are based on advisory information provided by Volcanic Ash Advisory Centres.
14.2.3 Tropical cyclone (TC) SIGMET messages issued are based on TC forecast issued by HKO, advisory information provided by Tropical Cyclone Advisory Centres and local weather observations.
14.2.4 SIGMET information is disseminated via the AFTN and broadcast in VOLMET service during the period of validity of the SIGMET information (see Table GEN 3.5.13 VOLMET Service).
14.3 AERODROME WARNING SERVICE
14.3.1 The AMO issues aerodrome warnings for HKIA in both abbreviated plain language and plain language if one or several of the following phenomena are occurring or expected to occur at the airport:
  1. Tropical cyclone (if the 10-minute mean surface wind speed at the aerodrome is 34 kt or more);
  2. Thunderstorm;
  3. Hail;
  4. Snow;
  5. Freezing precipitation;
  6. Hoar frost or rime;
  7. Sandstorm;
  8. Duststorm, rising sand or dust;
  9. Strong surface wind and gusts (if the 10-minute mean surface wind speed exceeds 21 kt or the gusts exceed 31 kt at the aerodrome);
  10. Squall;
  11. Frost;
  12. Volcanic ash;
  13. Tsunami;
  14. Volcanic ash deposition;
  15. Toxic chemicals;
  16. Tornado and waterspout.
14.3.2 See para. 4.5 - para. 7 for the low-level wind shear and turbulence warning services provided for HKIA.

15  Other Automated Meteorological Services

15.1 AVIATION METEOROLOGICAL DATA PROCESSING SYSTEM (METPS)
15.1.1 The Aviation Meteorological Data Processing System (METPS) is operated by the AMO to provide meteorological information to operators as well as the Airport Authority and ATC units. Meteorological information is made available to operators via a sub-system of METPS, viz. the Aviation Meteorological Information Dissemination System (AMIDS).
15.2 DATA LINK-ATIS (D-ATIS) AND DATA LINK-VOLMET (D-VOLMET)
15.2.1 Data link-ATIS (D-ATIS) and Data link-VOLMET (D-VOLMET) services are provided by CAD. They comply with the Airlines Electronics Engineering Committee (AEEC) Specifications 618, 620, 622 and 623. Aircraft equipped with ACARS meeting these AEEC specifications and with connectivity to the SITA Aircom network can request and obtain D-ATIS and D-VOLMET messages. There is inter-networking arrangement between SITA and ARINC to exchange D-ATIS and D-VOLMET messages from one network to the other. Operators should check with their service providers for further details.
15.2.2 The airport ID for the Hong Kong D-ATIS and D-VOLMET is VHHH.

16  Tropical Cyclones and Strong Monsoon Winds

16.1 TROPICAL CYCLONES
16.1.1 Tropical cyclones may occur over the South China Sea at any time of the year, but have only produced persistent winds of gale force or over (mean wind speed exceeding 33 kt) in the Airport area during the months of May to November. On one occasion (during the passage of Super Typhoon Mangkhut in 2018), the mean hourly wind speed reached 61 kt at HKIA and gusts of up to 84 kt were recorded.
16.1.2 Warnings issued by the Hong Kong Observatory: 
  1. SIGMET messages
    SIGMETs for tropical cyclones within the Hong Kong FIR are issued by the AMO for dissemination beyond the aerodrome and broadcast to aircraft in flight (see GEN 3.5 para. 14).
  2. Hong Kong's Tropical Cyclone Warning Signals
    For tropical cyclones that may pose a threat to the territory, warnings are also issued by the HKO to a number of addressees including the Air Traffic Services Units, the Rescue Co-ordination Centre and to the Airport Terminal Building Information Office. In addition, the HKO passes the information to the Information Services Department for dissemination to the public through the press, radio and television. The following signals are used in Hong Kong:
    SignalsMeaning
    No. 1 (Standby Signal)A tropical cyclone is centred within about 800 km (432 NM) of Hong Kong and may affect the territory
    No. 3 (Strong Wind Signal)Strong wind is expected or blowing generally in Hong Kong near sea level, with a sustained speed of 41-62 km/h (22-33 kt), and gusts which may exceed 110 km/h (59 kt), and the wind condition is expected to persist
    No. 8 NW
    No. 8 SW
    No. 8 NE
    No. 8 SE
    (Gale or Storm Signal)    		Gale or storm force wind is expected or blowing generally in Hong Kong near sea level, with a sustained wind speed of 63-117 km/h (34-63 kt) from the quarter indicated and gusts which may exceed 180 km/h (97 kt), and the wind condition is expected to persist
    No. 9 (Increasing Gale or Storm Signal)Gale or storm force wind is increasing or expected to increase significantly in strength 
    No. 10 (Hurricane Signal)Hurricane force wind is expected or blowing with sustained speed reaching upwards from 118 km/h (64 kt) and gusts that may exceed 220 km/h (119 kt)
  3. Tropical Cyclone Warning Bulletins
    Tropical Cyclone Warning Bulletins issued by the HKO are disseminated to the various addressees and broadcast by all radio and television stations and given in the HKO website.
  4. Further information on the signals and warning services provided are available from the HKO website.
16.1.3 Precautions
16.2 STRONG MONSOON WINDS
16.2.1 Introduction
When strong to gale force winds which are not associated with tropical cyclones are occurring or expected to occur in Hong Kong, the HKO will issue the Strong Monsoon Signal. This signal is used mainly in winter in connection with winter monsoon winds from the northeast quadrant and occasionally in summer when the southwest monsoon is strong.
16.2.2 Warnings issued by the HKO
Warnings for strong monsoon winds are issued by the HKO whenever the mean wind speed near sea level anywhere in Hong Kong exceeds, or is forecast to exceed, 21 kt. These winds may sometimes reach 38 kt or more in very exposed places.
16.2.3 Owners of aircraft are advised to take early actions to safeguard their equipment by carrying out precautions which may appear necessary. Owners may be held responsible for any damage caused by their equipment.

17  Local Wind Effects on the Approach to and Departure from Hong Kong International Airport

17.1 GENERAL WARNING
17.1.1 Due to the proximity of the hilly terrain of Lantau Island to the south and east of Hong Kong International Airport, significant low-level windshear and moderate to severe turbulence can be expected along the approaches to and departures from the runways when winds blow off these hills, i.e. from east through southwest at about 15 kt or more. As the hills to the north are further away, they play a less significant role, but nonetheless can create local wind effects when strong winds blow off these hills, i.e. from northwest through northeast, at about 20 kt or more.
17.1.2 The terrain induced wind disturbances from nearby hills can be of very small scale, sporadic and transient in nature. Whilst these wind disturbances may be small in physical dimension and correspond to only several seconds of flight time, significant headwind changes (i.e. runway orientated wind speed losses and/or gains being 15 kt or greater), can be expected as the aircraft flies through them. The sporadic and transient nature of the terrain-induced wind disturbances results in some aircraft experiencing windshear and/or turbulence, whilst others do not, even though the broad meteorological conditions are the same. Successive aircraft which experience wind shear and/or turbulence may also encounter a different sequence of events.
17.1.3 Surface winds at the airport are generally not good indicators of the wind that may be experienced during the final phase of the approach. Winds at approximately 2 000 ft may be a better representation of the prevailing wind conditions in the region. Generally, mean wind speed should decrease towards lower altitudes but isolated strong gusts may be expected. Wind direction would also change with altitude due to blocking of the general wind flow by nearby hills or in the presence of low-level temperature inversion which occurs mostly in the cool season (about half of the time or more from November to April). It is possible for the magnitude of wind shear and turbulence to increase towards final approach, resulting in deteriorating rather than improving conditions prior to touchdown.
17.2 EASTERLY THROUGH SOUTHWESTERLY WINDS
17.2.1 When prevailing winds are from the east through southwest and with a speed in excess of 15 kt, significant wind shear and moderate turbulence can be expected on the approaches to or on departure from the runways. Larger magnitude wind shear and turbulence is possible when the wind speed is in excess of 30 kt. Because of the proximity to the hills of Lantau, wind shear and turbulence are more significant over the south runway (RWY 07R/25L).
17.2.2 Low-level wind shear and turbulence are expected to be more significant when the wind is from the direction 130° - 210°, especially in the presence of low-level temperature inversion or when the wind speed is more than 30 kt.
17.3 NORTHWESTERLY THROUGH NORTHEASTERLY WINDS
17.3.1 Significant low-level wind shear and moderate turbulence can be expected when wind speeds exceed 20 kt, especially for approaches to RWY 25 and along the departure and missed approach corridors from RWY 07 as these approach/departure corridors are closer to the hills to the north as compared with approaches to RWY 07 or departure from RWY 25. Larger magnitude wind shear and turbulence over these approach and departure corridors is possible if the wind speed exceeds 30 kt, especially around the last 15 NM from the threshold when on final approach to RWY 25.
17.4 LAND-SEA BREEZE
17.4.1 Land-sea breeze is not a strong wind phenomenon but it can create a complex wind field in the vicinity of the airport and it can cause a significant change in wind direction within a distance of a few kilometres along the approach/departure areas. If the sea breeze opposes the prevailing wind flow it can result in significant wind shear even in fine weather conditions. 
17.5 LOW-LEVEL JETSTREAM IN COOL SEASON
17.5.1 During a surge of the winter monsoon, strong low-level jets of northeasterly wind with speeds up to 50 kt occasionally affect the airport. Under such circumstances significant windshear along the departure corridors of RWY 07 can be expected.
17.6 LOW-LEVEL WIND EFFECTS
17.6.1 Pilots should be aware of the possibility of building-induced mechanical turbulence and wind shear effects when landing on Hong Kong International Airport’s
  1. RWY 25L in strong northwesterly / northerly winds;
  2. RWY 25C in strong southwesterly / southerly / southeasterly winds;
  3. RWY 25C in northwesterly / northerly / northeasterly winds with a background speed of about 15 knots or more;
  4. RWY 25R in strong southerly winds; and
  5. RWY 07R touch down zone in northwesterly / northerly winds with a background speed of about 15 knots or more.
17.6.2 Pilots should be aware of the possibility of building-induced mechanical turbulence and wind shear effects when taking off beyond the mid-point of Hong Kong International Airport’s RWY 07C in northwesterly / northerly / northeasterly winds with a background speed of about 15 knots or more. 
Charts
Page Chart name PDF
GEN 3.5-HKO-EQ Location of HKO Equipment
PDF ../pdf/VH-GEN-3.5-HKO-EQ.pdf