Airports Company South Africa (ACSA) is in the process of replacing the meteorological instrumentation at Johannesburg, Cape Town, Durban, Port Elizabeth, George, East London and Pilanesberg airports with state of the art automated weather observing systems. These systems use latest technology initiatives and will be commissioned and operational in July 2006.
“ACSA has procured the services of a contractor for the supply and installation equipment. The system will be managed by ACSA who have also entered into a maintenance agreement with the equipment contractor on a three-year renewable contract basis. The equipment, worth R25 million, is presently being manufactured by Vaisala, a Finland-based global market leader in aviation weather systems, under contract to Siemens Southern Africa,” says John Neville, ACSA’s acting Group Executive: Aviation Services.
“In conditions of adverse weather, such as those of low cloud, mist and heavy thunderstorms we have been experiencing lately, this equipment is mission critical. As a company that firmly believes in providing world-class standards, we are pleased with this equipment as it will go a long way in ensuring the continued safety at our airports,” Neville added.
As per International Civil Aviation Organisation (ICAO) requirements, ACSA will feed the “raw” data from the field sensors to the weather services, who will verify the data. The weather services will then feed the data to the air traffic control (managed by Air Traffic and Navigation Services Company), who activates, amongst others, the necessary airfield lighting category and instrument landing system category and informs the pilot of the weather conditions.
Civil aviation standards require that observations of meteorological conditions are conducted at airports. The objective of these observations is to contribute towards the safety, regularity and efficiency of aircraft operations during takeoff and landing.
This objective is achieved by supplying the necessary meteorological information to air traffic service units, who provide the information to flight crew members, search and rescue services units and others concerned with the conduct or development of air navigation.
The observation of meteorological conditions is made by means of field instruments, which are strategically located on the airfield in relation to the runway. The type and number of sensors that are installed at an airport, depend on the prevailing weather conditions.
For example, weather conditions at Cape Town International Airport, are such that at times the airport operates under zero visibility conditions (ie due to fog, mist, clouds, etc). While on the other hand, weather conditions at Pilanesberg International Airport, is generally good visibility conditions. More sensors are required for operations in poor visibility conditions.
Typical field instruments located on the airfield include:
Runway Visual Range Sensors: These sensors measure visibility and are located parallel to the runway edge.
Ceilometer Sensors: These sensors measure cloud height and are located at the runway thresholds.
Other sensors include: wind speed and wind direction sensors, temperature and humidity sensors, pressure sensors, rain gauge and solar radiation sensors.