![]() ![]() The plume hight has been confirmed by aircraft to 12 km or higher. Europe's Central Flow Management Unit (CFMU) said on May 21st: "CFMU had been adviced by Icelandic met office that there has been a volcanic eruption of volcano Grimsvotn in Iceland at 20110521 1900Z. Rather than the current undefined approach of delineating areas with “no ash”, the team felt that there was a need to delineate an area in which existed a significant risk of a substantive adverse safety outcome." ICAO has followed with a recommendation for rule makers - national Civil Aviation Authorities - and operators - airlines - how to deal with the threat of ashes in principle enabling operators under supervision of civil aviation authorities to decide themselves to fly or not to fly after conducting and documenting mandatory risk assessments. As a result, ICAO recommends that aircraft avoid exposure to volcanic ash, regardless of the ash concentration latterly, this has been termed the avoidance of 'visible ash'" and continued: "As a consequence of the lack of clarity as to what level of ash constitutes an unsafe level, the team also noted that there was no clear specification from the aviation community to the VAACs as to the level of ash contamination to be depicted on VAAC products. ICAO said: "ICAO Doc 96913 acknowledges that there is, as yet, no agreement as to the ash concentration level that would constitute a hazard to aircraft engines. According to NOAA's GFS weather data there are no significant high level winds above or around Iceland, high level wind directions are varying and wind speeds mainly computed below 20 knots, at the northern coast of Iceland up to 40 knots. In the afternoon of May 25th they reported that the eruption was much stronger and had produced substantially more ashes than Eyjafjoll's eruption last year. Starting around 03:00Z May 25th there has been no new output of volcanic material. The Icelandic Meteorologic Institute reported in the morning of May 25th that there is clear evidence that the eruption of Grimsvotn has stopped. Only "old" ashes already in the air still hamper air traffic. The scientists are hopeful by comparing the eruption with previous events, that by weekend the eruption might cease. The Icelandic Meteorologic Institute reported late May 24th that the plume of new ashes has reduced to about 2000 meters of height no longer posing a danger for aviation. About one hour after the begin of the eruption the ash cloud however had already reached 11,000 meters (F元60), the Icelandic Meteorologic Institute reported. Scientists said on May 21st, that it was unlikely the eruption would cause similiar disruption to European Air Traffic like Eyjafjoll last year (see: Icelandic volcano disrupted aviation in Europe, Europe returning to normality). People in the Scottish Highlands reported finding their cars covered with volcanic ash Tuesday Morning (May 24th). On May 23rd 19:00Z most of the Icelandic Airspace opened again for IFR traffic including Keflavik Airport. The entire Iceland Airspace was subsequently closed for IFR traffic. Iceland's Keflavik Airport suspended IFR operations at approximately 10:00L (10:00Z) on May 22nd (not NOTAMed so far), all flights for the day have been cancelled. ![]() The eruption significantly reduced in intensity during May 24th and stopped early May 25th. On May 22nd 06:00Z radar data estimated the ash plume to raise up to 15,000-17,000 meters (FL490-FL560). However, this time the volcano ash cloud has already been reported above F元00, the danger zone has been identified up to FL550 with the cloud estimated to have reached FL500. Icelandic Volcano Grimsvotn has erupted at 17:30Z on May 21st 2011, a minor eruption had already been expected similiar to the ones in the past (last in 2004). ![]()
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