Aircraft allowed to fly despite volcanic ash

Date: 18/5/2010

Aircraft may be able to fly later today (May 18th) despite closures of airspace caused by volcanic ash, according to the UK Civil Aviation Authority (CAA).

Chief Executive Andrew Haines said: "The world's top scientists tell us that we must not simply assume the effects of this volcano will be the same as others elsewhere."

Mr Haines added that aircraft will now be able to travel in a new zone if they put forward a safety case to the CAA that incorporates an agreement between the manufacturer of the engine and the manufacturer of the aircraft.

Airplane and engine experts have deemed it safe to fly in a new zone for a set amount of time with higher ash densities.

The CAA stated a Time Limited Zone has been created between the black No Fly Zone and the red Enhanced Procedure Zone.

Volcanic ash is an abrasive substance that causes friction and wear on vanes and blades in an aircraft's engine.

This can then affect the aerodynamics of the compressor, ultimately causing it to lose thrust, which could cause the engine to stall.