Grounding jets due to ash cloud 'was correct'

Aviation authorities were right to ground commercial jets for seven days after last year's volcanic eruption in Iceland, a study has found.

Safety fears led to the action as fine ash from the Eyjafjallajokull volcano blew into the path of aircraft over the UK and continental Europe.

The decision disrupted travel for about ten million passengers and cost as much as 2.2 billion, leading some critics to question whether it was justified.

But a scientific report published today in the journal Proceedings of the National Academy of Sciences concludes it was.

Researchers analysed samples of ash from the volcano and found they were capable of causing an air disaster.

The fragments remained "sharp and abrasive" even after attempts to blunt the particles by stirring them in water. They would have sandblasted aircraft windows, making them impossible to see through, and had the potential to stall engines.

The explosive nature of the eruption on 14 April last year was caused by glacial meltwater coming into contact with hot volcanic magma. Tiny pieces of extremely hard, abrasive material were ejected to heights of more than 9km (about 5.5 miles) and carried as far as Russia.

Fears over volcanic ash arose from an incident in 1982 when a British Airways 747 flew through debris from the erupting Mount Galunggung in Indonesia.

The pilot reported sparks from the windows and wings, and all four engines failed when melted ash coated their interior.

Laboratory tests carried out on the Icelandic ash suggested that a similar event could have happened again.