Nuclear emergency warning issued for 10 airspace regions
Concern over a possible radioactive hazard from Japan's damaged Fukushima nuclear power plant has prompted a formal warning from airspace monitors.
London Volcanic Ash Advisory Centre has issued a nuclear emergency message covering 10 flight information regions.
Among them are airspace zones in China, Korea, Russia and the USA.
The emergency message is timed at 03:00UTC on 15 March, and is open-ended.
It identifies the affected flight information regions as Fukuoka - the extensive region which encompasses Japanese airspace - plus Manila, Taibei, Shanghai, Incheon, Pyongyang, Vladivostok, Khabarovsk, Yuzhno-Sakhalinsk and Anchorage.
London VAAC handles advisories linked to the threat of volcanic eruption and was heavily involved in co-ordination efforts during the Icelandic ash crisis last year.
At a meeting of the International Airways Volcano Watch operations group in Bangkok, in 2007, the London centre was invited to be the "focal point" for notifying en route air traffic control centres of International Atomic Energy Agency warnings over accidental release of radioactive material.