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VA (1)
- Usado para
- volcanic ash
- Fonte1
- WORLD METEOROLOGICAL ORGANIZATION. Manual on codes: international codes: volume I.2: annex II to the WMO technical regulations: parte B: binary codes. parte C: common features to binary and alphanumeric codes. Geneva, 2015. (WMO, n.306).
- Definição2
- Volcanic Ash is comprised of minerals unique to the volcanic eruption. Minerals common to most volcanic ash are silica together with smaller amounts of the oxides of aluminium, iron, calcium and sodium. The glassy silicate material is very hard and extremely abrasive. Its melting point is below jet engine burner temperature which introduces additional hazards. (refer section 2.1 of ICAO Manual on Volcanic Ash, Radioactive Material and Toxic Chemical Clouds - Doc 9691).
- Fonte2
- INTERNATIONAL CIVIL AVIATION ORGANIZATION. Flight safety and volcanic ash: risk management of flight operations with known or forecast volcanic ash contamination. Advance edition (unedited). Montreal, 2012. (Doc. 9974)
- Fonte3
- WORLD METEOROLOGICAL ORGANIZATION. Manual on codes: international codes: volume I.2: annex II to the WMO technical regulations: parte B: binary codes. parte C: common features to binary and alphanumeric codes. Geneva, 2015. (WMO, n.306).
- Fonte4
- INTERNATIONAL CIVIL AVIATION ORGANIZATION. Manual on Volcanic Ash, Radioactive Material and Toxic Chemical Clouds. Third edition. Montreal, 2015. (Doc. 9691).
- Contexto
- Volcanic ash (VA), when expected, is always forecast regardless of visibility.
- In addition to volcanic ash, volcanic eruption columns also contain many gases including water vapour, sulphur dioxide, chlorine, hydrogen sulphide and oxides of nitrogen. While the proportion of each of these gases in particular volcanic eruptions varies widely, the predominant constituent gases are water vapour, sulphur dioxide and chlorine. In their gaseous form these constituents of the volcanic ash cloud are not thought to cause significant harmful effects to aircraft.
- Engines are very slow to accelerate to idle at high altitude, especially in volcanic ash — this may be interpreted as a failure to start or as a failure of the engine to accelerate to idle or as an engine malfunction;
- Português
- cinza volcânica