Sunday, 18 April 2010
Why European airspace is closed? Eyjafjallajökull eruptions and 1982 BA flight 009
All flights to and from the UK and parts of Europe remained cancelled from 15th April, 2010. The reason was a volcano eruption over 1,000 km away. Eyjafjallajökull eruptions has similarity with eruptions of Mount Galunggung and BA flight 009 in June 1982. In history of aviation this incident is also the cause of a classic masterpiece of understatement that goes as:
“ Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them under control. I trust you are not in too much distress.
On 15 April 2010, a volcano under the Eyjafjallajökull glacier in Iceland erupted and strong winds pushed the ash cloud towards Western and Central Europe. Almost all of the European airspace from Milan / Italy and north thereof was closed to prevent another incident similar to Flight 009. BA 009 was a British Airways aircraft carrying 240 passengers, accidentally entered the ash cloud during night time in June 1982 150 km downwind of the volcano. All four engines failed and the aircraft descended for 16 minutes, losing 7500 metres of its 11500 meter altitude, until the crew managed to restart the engines.
Mount Galunggung (Indonesian: Gunung Galunggung, formerly spelled Galoen-gong) is an active stratovolcano in West Java, Indonesia. The last major eruption on Galunggung was in 1982, which had a Volcanic Explosivity Index of 4 and killed 68 people. This eruption also brought the dangers of volcanic ash to aviation to worldwide attention, after two Boeing 747 passenger jets flying downwind of the eruption suffered temporary engine failures and damage to exterior surfaces, both planes being forced to make emergency landings at Jakarta.
The following month a Singapore Airlines aeroplane with 230 passengers aboard also inadvertently entered the cloud at night time, and three of its four engines stopped. The crew succeeded in restarting one of the engines after descending 2400 meters. Both aircraft suffered serious damage to their engines and exterior surfaces.
British Airways Flight 9, sometimes referred to as the Speedbird 9 or Jakarta incident, was a scheduled British Airways flight from London Heathrow to Auckland, with stops in Bombay, Madras, Kuala Lumpur, Perth, and Melbourne.
On 24 June 1982, the route was flown by City of Edinburgh, a 747-236B. The aircraft flew into a cloud of volcanic ash thrown up by the eruption of Mount Galunggung (c. 180 km south-east of Jakarta, Indonesia), resulting in the failure of all four engines. The reason for the failure was not immediately apparent to the crew or ground control. The aircraft was diverted to Jakarta in the hope that enough engines could be restarted to allow it to land there. The aircraft was able to glide far enough to exit the ash cloud, and all engines were restarted (although one failed again soon after), allowing the aircraft to land safely.
How Does Volcano Ash Cause Aircraft Engine Failure?
Several factors combine to make some volcanic eruptions a danger to aircraft. The first is that the particles in volcanic ash are composed of hard materials, such as rock, glass and sand. The second factor is that when these particles are ejected high enough, they may be picked up by the high winds that can disperse them over large distances. A third factor is that the dust plume is not dense enough to be easily seen by airline pilots, but it is dense enough to cause severe damage to the engines, which may cut out and fail. Failure happens when the fine dust particles block up the air vents.
Alaska Eruption at Redoubt Volcano - KLM Flight 867
In this case, the aircraft dropped from 25,000 feet to just 12,000 feet when all four of the engines cut out, on the Boeing 747. The incident happened when the jet flew through a cloud of high level ash from Redoubt volcano, Alaska. The pilot and crew were eventually able to restart two of the four engines, which was enough to keep the plane airborne long enough to land at Anchorage, Alaska. None of the passengers or crew were hurt. A contributing factor in this case was the height of the volcano, at over 10,000 feet.