Lasers and satellites track ash cloud

According to the UK's Met Office, the eruption of Iceland's Eyjafjallajoekull volcano is "weakening", but weather patterns, for the time being, continue to blow volcanic ash towards the UK.

Nats, the UK's air traffic control authority, described the current situation as "continuously improving" but added that it was difficult to forecast.

David Shukman reports on the different methods experts are using to track the course of the ash cloud.