
Weather Services for Aviation
Overview of the services:
Within the framework of the International Civil Aviation Organization (ICAO),
the Hong Kong Observatory (HKO) is the designated meteorological authority
in Hong Kong to provide weather services for international air navigation.
The provision of aviation weather services is to contribute towards the
safety, regularity and efficiency of international aircraft operations.
This is achieved by supplying the necessary meteorological information
to Air Traffic Services (ATS) units, airline operators, flight crew members,
airport management and others associated with international air navigation.
History:
The HKO's long association with aviation began in 1920 when proposals
for an aviation weather service were first discussed. Aviation forecasting
service began in 1937 and a forecaster was stationed at Kai Tak Aerodrome
on a part-time basis. The Airport Meteorological Office (AMO) at
the Kai Tak Terminal Building came into operation in 1939. After
the Second World War, the HKO resumed the provision of aviation weather
services in August 1947. In response to the rapid growth of air traffic
in the post-war years, a team of aviation forecasters was recruited in
1957 to man the AMO. Since then the AMO witnessed the continuous
growth in air traffic volume at Kai Tak.
With the opening of the new Hong Kong International Airport (HKIA) at Chek
Lap Kok in July 1998, the AMO carries on with its operations at the Air
Traffic Control Tower. New meteorological systems based on state-of-the-art
technologies were implemented to enable the AMO to cope with the increasing
demand.
Weather Observation
and Forecasting:
Weather observers and aviation forecasters work round-the-clock at the
AMO to take routine and special weather observations and to provide enroute
forecasts as well as aerodrome forecasts for the HKIA.
Fig. 1 Making weather observations
Six sets of anemometers are installed in the middle and at both ends of
the Northern and Southern Runways to measure the wind direction and speed
an aircraft will encounter during take-off and landing. There are
also six sets of Runway Visual Range (RVR) transmissometers to measure
visibility conditions along the two runways.
Fig. 2 An anemometer near the runway
Thermometers, barometers, raingauges and a ceilometer are set up in a meteorological
enclosure near the Air Traffic Control Tower to provide temperature, pressure,
rainfall and cloud base information for the aerodrome.
Additional ceilometers are installed at Siu Mo To and Tai O to assist the
observation of cloud base over the approach and departure areas.
Fig. 3 Locations of meteorological equipment around the airport
The
observations and forecasts are disseminated to ATS units for onward transmission
to aircraft pilots, to airline operators for pre-flight planning and to
local users operating helicopters and light aircraft. Such information
as well as weather reports from neighbouring aerodromes are included in
the regular broadcasts for aircraft in flight and for aircraft preparing
for landing at or taking off from the HKIA.
Aircraft observations of winds, air temperatures and special phenomena
are compiled by the AMO and disseminated as aircraft reports.
Warning Services:
The AMO is responsible for issuing warnings on hazardous weather which may affect the safety of aircraft operations within a designated airspace over the northern part of the South China Sea. The AMO also issues aerodrome warnings on adverse weather for protection of aerodrome facilities and aircraft on the ground.
To enhance the safety of aircraft landing at and taking off from the HKIA,
the AMO issues alerts of low-level windshear and turbulence. A Terminal
Doppler Weather Radar (TDWR), a network of over 20 anemometers and two
wind profilers are used to assist in the detection and warning of windshear
and turbulence.
Fig. 4 Terminal Doppler Weather Radar at Tai Lam Chung
Fig. 5 Schematic diagram of windshear caused by a microburst
Low-level windshear and turbulence alerts for the approach and departure
areas within 3 nautical miles of the runway thresholds are issued by the
AMO for relay by air traffic controllers to approaching and departing aircraft.
Service Delivery:
A meteorological data processing system acquires, processes and disseminates
meteorological information to support the operation of the HKIA. This system
is connected with the systems of the Civil Aviation Department (CAD) for
exchange of operational weather data with airports around the world, and
for display of meteorological information to air traffic services units.
This system also includes an on-line information service through which
airline companies can retrieve flight documentation including forecast
charts of en-route significant weather and wind/temperature data issued
by the World Area Forecast Centres at London and Washington, weather forecasts
for departure, destination and alternate aerodromes, as well as the latest
meteorological information of weather radar and satellite images, aerodrome
warnings, tropical cyclone information, etc. Weather briefings
are provided via telephone or video conferencing equipment to flight crew
members on request.
Fig. 6 A sample significant weather chart
New Development:
HKO will constantly use the latest technology to ensure efficient service
delivery. Improvement of various warning services including windshear
warnings will continue with a view to further increasing accuracy and reducing
false alarms. Following international trend, plan is in hand to develop
capabilities for real-time downlink of weather data obtained by aircraft
and uplink of weather information required in the cockpit.
For more information, please visit the Aviation Weather Services web page
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