Introduction
Danger of Volcanic Ash Clouds
Volcanic ash clouds are a serious hazard to aviation. They can cause damage to aircraft engines, reduce visibility, and pose a threat to flight safety. We provide real-time information on volcanic ash activity, allowing pilots to avoid dangerous areas and make informed decisions about their flight paths.
The nine VAACs (Volcanic Ash Advisory Centres), have been designated by the International Civil Aviation Organization to provide their expertise to civil aviation in case of significant volcanic eruptions.
The nine VAACs
This is an experimental feature, currently limited to the VAACs highlighted in green above. If there is sufficient interest from the community, we will expand it to cover the rest of the world.
Effects of Volcanic Ash
Source: skybrary.aero
Volcanic Ash encounter can result in engine damage and malfunction:
- Engine Malfunction. The principal risk to continued safe flight, arising from flight through high concentrations of volcanic ash, is the melting within the engine of ash particles, which are predominantly composed of silicates with a melting point of 1100°C. This melting point is considerably less than the core operating temperature of high by pass turbine engines which, at normal thrust settings, is at least 1400°C; there will be a trend for the core temperature to increase as engine design focuses on improved specific fuel consumption. Ingested silicate ash melts in the hot section of the engine and then fuses onto the high pressure turbine blades and guide vanes. This drastically reduces the throat area and both static burner and compressor discharge pressures rapidly increase and cause engine surge. Transient and possibly terminal loss of thrust can occur in the most severe cases with a successful engine re-start only possible if clear air can be regained. If present at sufficient densities, ash particles can also contribute to engine malfunction by simple deposition. In either case, the added debris clogs up the engine airflow and is likely to initially lead to engine surging and ultimately to a Flame Out. Reducing the thrust setting quickly to idle may lower the core temperature enough to prevent silicates melting.
- Long Term Engine Damage. The abrasive effect of volcanic ash particle impact can cause surface roughness inside turbine engines which, whilst it will not affect their continued normal operation, will result in a reduced specific fuel consumption. It is impossible to repair such damage, so the life of an affected engine could be considerably reduced.
- External Surface Corrosion. Ash can cause significant damage to the exposed surface of the aircraft skin and to the outer ply of windscreens. If the ash encounter is severe, the latter may become sufficiently abraded to be difficult to see through.
Bristish Airways BA-9 - Engine damage due to volcanic ashes from Galunggung volcano on 24 June 1982
