Tracking ash the new old fashioned way: MOCCA

A  purpose-equipped aircraft for tracking and measuring atmospheric volcanic ash in northern Europe has just been approved for operation on behalf of the UK Met Office.

Known as the Met Office Civil Contingency Aircraft (MOCCA), it is a specially equipped twin-engine Cessna 421C, piston-powered to give it greater resilience when it encounters ash that would damage turbines. 

It has been fitted out by Cranfield Aerospace with an array of different sensor devices that will enable it to "see" ash concentrations at different levels, but also take measurements of actual atmospheric contaminants for analysis.

This multi-purpose sensor mounted under the starboard wingtip is not exactly aerodynamic, but it detects, measures, identifies and samples particles of all types - and gases - in the atmosphere. 

Below, there's a Brechtel probe on the right of the nose looking like an oversized pitot tube...

The aircraft, G-HIJK built in 1977, is pressurised for high altitude flight and powered by two Teledyne Continental turbocharged engines. It is so packed with onboard specialist equipment that there is room only for a maximum crew of three, but the operator, special missions company DO Systems based at Bournemouth, UK, says a typical mission crew would be a single pilot and a Met Office systems operator.

Data on ash and other atmospheric pollutants is gathered and transmitted in frequent bursts by satellite communications to receivers on the ground managed by the London Volcanic Ash Advisory Centre, which is a Met Office responsibility.

Managing Director of Cranfield Aerospace David Gardner emphasised that the aircraft, while primarily intended to contribute to multinational efforts to enable safe aviation operations when volcanic ash is affecting Europe's airspace, it can also detect and monitor other atmospheric pollutants, hence the Cessna's generic description as a "civil contingencies" aircraft.

Under the port wingtip is a probe that measures position, altitude (by differential GPS), pressure, temperature, humidity and atmospheric behaviour - like turbulence - which puts in context all the other measurements.

As regards other environmental tasks that the MOCCA aircraft can undertake, Gardner cites the example of the Buncefield oil storage site conflagration a few years ago. The aircraft's sensors can identify atmospheric pollution levels that result from such an event, the locations that will be affected, and the risks involved.