Effects of low concentrations of volcanic fallout dust intake on jet aircraft engines
UPDATE (19 November 2010): the U.S. Defense Threat Reduction Agency has now declassified many of its vital, formerly secret nuclear weapons effects research reports on the implications of various silicate (volcanic dust-like) fallout particle intake concentrations upon the operation of different jet aircraft engines:
DNA-TR-82-18: Dust-Cloud Effects On Aircraft Engines-Emerging Issues and New Damage Mechanisms (U)
DNA-TR-87-106: Characterization of Dust Environments for the F.I07, TF-33, and J.57 Engine Tests (U)
DNA-TR-90-72-1: Exposure of Air Breathing Engines to Nuclear Dust Environment (U)Volume I-Performance Deterioration of an Operational F100 Turbofan Engine Upon Exposure to a Simulated Nuclear Dust Environment (U)
DNA-TR-90-72-3: Exposure of Air Breathing Engines to Nuclear Dust Environment (U)Volume III-Performance Deterioration of a Second F100 Turbofan Engine Upon Exposure to a Simulated Nuclear Dust Environment (U)
DNA-TR-91-160: The "Most Probable" Dust Blend and Its Response in the F-I00 Hot Section Test System (H STS)
DNA-TR-91-26: Response of an Operational Turbofan Engine to A Simulated Nuclear Dust Environment (U)
DNA-TR-92-111: The Response of an F107-WR-102 Engine to a "Most Probable" Nuclear Dust Environment (U)
DNA-TR-92-121: The Response of a YF101-GE-100 Engine to a "Most Probable" Nuclear Dust Environment (U)
DNA-TR-93-124: Response Models for the FIOI, TF33, and F107 Turbofan Engines to Dust Environments
DNA-TR-93-2: Influence of Ingested Nuclear Cloud Dust, and Overpressure Waves on Gas Turbine Engine Behavior (U)
DNA-TR-94-110: The Response of a Third F100-PW-100 Engine to a "Most Probable" Nuclear Dust Environment (U)
DNA-TR-94-24: The Response of a Second YF101-GE-100 Engine to a Dust-Laden Environment (U)
DNA-TR-94-45: The Response of a F112-WR-100 Advanced Cruise Missile Engine to a Dust-Laden Environment (U)
DNA-TR-94-46: The Response of a Second F112-WR-100 Advanced Cruise Missile Engine to a Dust-Laden Environment (U)
“A spokeswoman from the CAA told BBC News: "Air manufacturers, both engine and airframe, were asked to look at the scientific evidence from test flights and at the Met Office data, to understand how much volcanic ash in the atmosphere... jet engines could tolerate [without being] damaged." Now, scientists and engineers have agreed a safe threshold - a concentration of ash of 0.002g per cubic metre of air. At or below this concentration, there is no damage to the engine. Current data suggested that concentrations of ash in UK airspace were around 100 micrograms (or 0.0001g) per cubic metre, explained Dr Grant Allen from the Centre for Atmospheric Science at the University of Manchester. ... Stephen Wright, a lecturer in the University of Leeds School of Process, Environmental and Materials Engineering, said that the UK's impeccable safety record in aviation would also have delayed the decision to lift the ban. He explained: ‘As well as the test flights, the authorities will have been trawling through historical data from episodes such as the first Gulf War, where the mass movement of troops in Saudi Arabia and Kuwait stirred up all the ultra fine sands in the region resulting in damage to the UK tornado aircraft fleet’.” - http://news.bbc.co.uk/1/hi/8634276.stm
“Before the initial grounding of UK flights in April, the rules were set by an international body called the International Civil Aviation Organisation. It had a limit of "no tolerance" for any concentration of volcanic ash. But since then, the Civil Aviation Authority (CAA) has raised the threshold for the concentration of ash based on test flights and analysis of the cloud. The CAA worked with scientists and engine and aircraft manufacturers to set a safe threshold for the concentration of ash of 0.004g per cubic metre of air. The authority initially set "conservative" threshold of 0.002g per cubic metre, which incorporated a "buffer" to ensure that planes could fly safely. New data, including reports from flights that have encountered ash, has now allowed manufacturers to confirm that the higher ash concentration will not damage aircraft or engines.” - http://news.bbc.co.uk/1/hi/uk/8627253.stm
“After weeks of disruption for millions of passengers, the Civil Aviation Authority (CAA) is expected to announce new rules which will allow planes to fly through areas with double the intensity of ash later today. The latest move will enable planes, with the agreement of aircraft and engine manufacturers, to travel through airspace affected by the volcanic ash cloud for limited periods. It is the second time the CAA has raised the density of ash threshold. Currently, planes are not allowed to fly through air that has more than 0.002g of ash per cubic metre of air. That figure is expected to double for limited flying periods to 0.004g. Yesterday's flight ban saw tens of thousands of passengers have their travel plans disrupted and provoked strong criticism from airline bosses including Willie Walsh, Michael O'Leary and Sir Richard Branson. Yesterday British Airways chief executive Willie called the airspace closure 'a gross over-reaction to a very minor risk' while Ryanair chief executive Michael O'Leary called the computer imagery systems used to monitor volcanic ash levels 'outdated, inappropriate and imaginary'. Nats, the National Air Traffic Service, also welcomed the news of a higher threshold, saying they were 'delighted' the less restrictive limits were being put in place meaning 'no predicted restrictions on UK airspace in the immediate future'. The Eyjafjallajokull volcano on Iceland began erupting last month prompting fears that ash could turn into molten glass when caught in the hot engines of a plane, which would potentially cut the engines mid-flight.” - http://thaitouristinfo.blogspot.com/2010/05/ash-cloud-planes-set-to-be-allowed-to.html
"German carriers Lufthansa and Air Berlin have expressed scepticism over the volcanic ash risk, and the need to keep airspace closed, after neither detected any technical problems during a series of positioning flights. ... A spokesman for the airline says that none of the aircraft showed any sign of volcanic ash damage. ... Dutch pilots' union VNV believes the concentration of volcanic particles is 'so small that it presents no danger'." - David Kaminski-Morrow, German carriers lead backlash over volcanic ash closures, Flightglobal, 18 April 2010.
Above: jet engines suck in and heat up air to about 2,000 °C, which well above the melting point of silicate minerals in volcanic ash and nuclear fallout from typical land surface bursts, so the dust melts, and in high concentrations this molten material can stick to parts inside the engine. Notice however that the BBC Met Office "prediction" of the ash fallout area is as naive as possible: it contains no iso-contours of concentrations levels whatsoever. It is completely meaningless because it doesn't discriminate between low and high concentrations of ash in the air. Accurate fallout predictions of concentrations allowing for diffusion and fallout of larger particles with downwind distance have been used for nuclear test dust clouds since the 1950s nuclear weapons tests.
Is the Met Office aware of this? The Met Office has allegedly been implicated in spreading or not debunking lying propaganda which denies the fact that natural climate changes make the artificial effect of human carbon emissions trivial by comparison: the current rate of rise of the oceans is 0.2 cm/year, less than one third of the average rate of rise of 0.67 cm/year which naturally occurred over the past 18,000 years, 0.67 cm/year. In the event of a nuclear terrorist attack, this kind of incompetence would be fatal, because being unable to accurately discriminate between different degrees of hazard, the "safety first" advice would cost lives by not accurately quantifying the hazards and allocating resources appropriately to those who are most in need of it. Lies by environmental liars, supported by "quiet agreement" by radiation standards quangos, concerning low level radiation after the Chernobyl accident led to 100,000 unnecessary abortions, 100,000 lives lost. This is an example of the problem of the "why take the risk?" philosophy. The "why take the risk?" argument for excessively low safety limits had a very heavy penalty in terms of human lives, 100,000 of them. Similarly, CND lies that "duck and cover" won't stop thermal flash burns and flying glass injuries in a nuclear attack, would maximise the number of casualties to deal with and thereby reduce the effectiveness of civil defence response, which could otherwise be focussed on the relatively few people with unavoidable injuries near ground zero.
"A plume of volcanic ash from Iceland has led to flights across the UK being grounded. The events around one British Airways flight in 1982 reveal the potential dangers of this sort of dust.
"Airports are being closed across the UK after dust which spewed from a volcano in Iceland, began drifting southwards. The experience of Capt Moody, almost 30 years ago, shows the potential danger clouds of volcanic ash present to modern jet aircraft.
"There had been no hint of trouble when flight BA 009 took off from Kuala Lumpur in Malaysia on the evening of 24 June, 1982.
"Heading for Perth, Australia, the weather forecast for the five-hour journey was good and the crew were anticipating an uneventful flight.
"Capt Moody, who had left the cockpit for a stroll, was summoned back to the flight deck. ... When he opened the door to the cockpit he saw the windscreen ablaze with a St Elmo's fire - a discharge of static electricity.
"Then Capt Moody's flight engineer detailed the impact the dust was having on the aircraft itself. Within a few moments, a passenger jet powered by four Rolls Royce engines had become a glider.
"Eventually, after quarter of an hour without any power, the engines were brought back to life. Ash had clogged the engines, which only restarted when enough of the molten ash solidified and broke off. [Nobody was hurt.]" - BBC
This BBC article states: "When all four engines on the Boeing 747 being flown by Captain Eric Moody shut down at 37,000ft, he hadn't a clue why. The plane had flown into a cloud of dust spewed out by an eruption of Mount Galunggung, 110 miles south east of Jakarta. A close examination of the plane revealed the damage a plume of these tiny particles can do to an engine - the tips of the turbine blades had been ground away. The findings were eventually incorporated into a report on the dangers of volcanic ash to aircraft."
There is a problem with using this close-in volcanic ash situation to infer such a hazard when aircraft are not 110 miles from a volcano, but 1,200 miles, which is the distance of London from Iceland. This is because the concentration of airborne ash decreases rapidly the further you go downwind, as a result of diffusion. Ultimately, some of the dust from any volcanic eruption diffuses into the air around the world. This doesn't mean that all aircraft should be grounded. The danger depends on the dust concentration. The lesson from the 1982 Boeing 747 experience at 37,000 feet near Jakarta, 110 miles from a volcano, is that the visible effects of dust on the aircraft such as static electricity on the windshield, correspond to turbine blade and dust clogging to the engines, and the crew of such an aircraft should get it out of the high concentration of dust immediately, just as they should avoid other aircraft, severe storms, mountains, etc.
Grounding aircraft over a thousand miles away from a volcano is not needed, judging from flights through low concentrations of volcanic dust (for a list of general consequences, see the paper linked here):
A number of airlines, including British Airways, have said they have carried out test flights within restricted zones with no obvious damage to aircraft.
BA chief executive Willie Walsh said analysis of its test flight and those of other airlines provided "fresh evidence that the current blanket restrictions on airspace are unnecessary".
Lord Adonis said: "In light of the test results we're getting from flights in Britain and similar test flights that have been taking place in Europe, discussions are taking place between the safety authorities and the manufacturers, to see whether there can be any updating of the safety regime for operating planes."
For five days, since Thursday 15 April 2010, all of Britain's airports have been closed because of confusion over the short term and long term risks from low concentrations of volcanic dust intake on jet engines. Now Royal Navy ships are being used to transport passengers!
As mentioned in a previous post, this airborne silicate dust damage threat was analyzed in June 1992 by J. R. Drake and others at RDA, in a revision of Chapter 20, Damage to Aircraft (report RDA-TR-2-2261-2201-001) of the secret Capabilities of Nuclear Weapons. The sand-blasting of jet engines by small irregular fused silicon fallout particles from nuclear detonations is similar to that caused by volcanic dust. The U.S. Department of Defense also have a separate secret Handbook for Analysis of Nuclear Weapons Effects on Aircraft, DNA 2084-1 Volume 1 and DNA 2084-2 Volume II. Alas, this Cold War data is not available to European Airlines or politicians, but is kept locked up in secret research laboratories.
Which is a shame, because it is costing airlines and millions of stranded passengers many millions, while the concentration of the volcanic dust over Britain has not proved enough to cause visible damage. If the airborne dust cloud is invisible to the eye (as this volcanic dust cloud over Britain is) the concentration of dust in grams per cubic metre is simply too low to cause any risk of engine failure. It won't sand-blast turbines to shreds and it won't clog air intakes. There is always some dust in the atmosphere, including rough particles of silicate (glass). These come from micrometeorites which are broken up during entry to the atmosphere from space, volcanic eruptions, erosion in sandy desert areas, etc. Aircraft are always flown through these natural low concentrations of airborne dust. Aircraft are designed to take it. As the dust concentration increases but remains invisible to the eye thousands of miles downwind from a volcanic eruption, the sandblasting of the engines will at least theoretically reduce the total engine lifespan or the time to full overhaul (worn engine parts can be replaced). However, this cost is not the overriding factor, requiring the grounding of aircraft, because engines will not shut down in such low (invisible) dust concentrations; the cost in replacing compressors and servicing engines needs to be offset against the costs of keeping aircraft grounded. You have to do a cost-benefit analysis that takes account of the costs to the airways of shutting down for long periods, thousands of miles from volcanoes, where diffusion has reduced the dust concentration to the extent that it is no longer visible:
Mr Bisignani, of the International Air Transport Association, has said the scale of the crisis facing the airline industry is now greater than at the time of the 9/11 attacks on the US.
"The decision that Europe has made is with no risk assessment, no consultation, no co-ordination, no leadership," he said.
"Europeans are still using a system based on a theoretical model which does not work... instead of using a system and taking decisions on facts and on risk assessment."
He said airspace closures were costing airlines $200m (£130m) a day in lost revenue.
European airlines have asked the EU and national governments for financial compensation for the closure of airspace, British Airways says. BA estimates that it is losing between £15m and £20m a day.
IATA's Giovanni Bisignani condemns European governments
At the weekend, some European airlines staged test flights through parts of the ash trail blowing from Iceland, leading to questions about whether the current flight bans were necessary.
Apart from the (over exaggerated) hazard to aircraft, the close-in volcanic ash is naturally toxic fallout because it can cause fluoride poisoning if inhaled in large quantities, resulting in "internal bleeding, long-term bone damage and teeth loss". Unlike radioactive fallout, the danger doesn't decay quickly with the -1.2 power of time. Close-in visible deposits of volcanic ash are a very long-term chemical hazard until the excess fluoride has been physically weathered out of the biosystem. Additionally, the fluoride in volcanic ash causes a corrosive effect on metals.
Instead of the government analyzing scientifically the concentration of airborne dust and evaluating whether it is cost-efficient to fly aircraft through (we know it is safe to fly aircraft through it, i.e. engines don't cut out in invisibly low dust concentrations), the government follows the scientifically inept BBC and instead confuses the close in threat from flying aircraft through visible dust clouds with invisibly low dust concentrations:
... according to current European regulations, no matter how low the concentration, aviation authorities will not reinstate normal control over airspace as long as the ash cloud remains.
A spokesperson from from Nats told BBC News that there was "no threshold" for concentrations at which volcanic ash was acceptable.
The dust is simply too dangerous for jet engines to risk commercial flights encountering it, said Nats.
This is just the political "no threshold theory", which in the context of radiation was discussed in an earlier post. The "no threshold" propaganda started with low level radiation in the 1950s. The idea is that if something is dangerous in large concentrations, it must also be banned in small concentrations, a form of pseudoscience which - if really true - would lead to most vitamins and minerals (which are dangerous in large amounts) being completely banned even in small concentrations, with tragic consequences.
The BBC has promoted this no-threshold theory by deliberately seeking to confuse the effects of observed visible dust clouds on jet engines with the lack of a problem at low concentrations:
In 1982, British Airways and Singapore Airways jumbo jets lost all their engines when they flew into an ash cloud over Indonesia.
Reports said that the ash sandblasted the windscreen and clogged the engines, which only restarted when enough of the molten ash solidified and broke off.
A KLM flight had a similar experience in 1989 over Alaska.
Stewart John, a fellow of the Royal Academy of Engineering and former president of the Royal Aeronautical Society, explained that the ash can cause severe damage.
"This dust really is nasty stuff," he told BBC News. "It's extremely fine and if it gets into a jet engine, it blocks up all of the ventilation holes that bleed in cooling air.
"Jet engines operate at about 2,000C, and the metals can't take that. The engine will just shut down."
In the case of the 1982 British Airways flight, Mr John explained, when the plane emerged from the cloud, the pilot repeatedly tried and failed to restart the engines.
"They were going down and down, and had just about accepted that they would have to ditch.
"But, at the last minute, one engine started. By repeatedly turning the engine over and having a clean airflow going through, he managed to blow the ash out."
Dr Rothery explained that as a result of those incidents, emergency procedure manuals for pilots were changed.
"Previously, when engines began to fail the standard practice had been to increase power. This just makes the ash problem worse," he said.
"Nowadays, a pilot will throttle back and lose height so as to drop below the ash cloud as soon as possible. The inrush of cold, clean air is usually enough to shatter the glass and unclog the engines.
"Even so, the forward windows may have become so badly abraded by ash that they are useless, and the plane has to land on instruments."
Mr John concluded: "We do not know how long this will last.
"It's like a typhoon - because you can't fly through it, you can't directly monitor it, so we have rely on satellite images and to err on the side of extreme caution."
Their logic is that something is either good or bad, so if dust causes engine failure in visible concentrations, it must be dangerous at all concentrations. This is contradicted by the evidence:
"Carriers grounded for days as a result of the ash cloud are becoming increasingly sceptical over the situation, particularly given that several positioning flights have revealed no evidence of technical threats.
"UK cockpit union BALPA acknowledges the pressure on air navigation services to take precautionary action but it is irritated at the extent and duration of the airspace closure over this particular volcanic eruption." David Kaminski-Morrow, UK pilots demand clarity on criteria to restore ash-hit flights, Flightglobal, 18 April 2010.
Today's article by David Kaminski-Morrow, ASH CLOUD LIVE: IATA furious at 'theoretical' basis for airspace closures, states:
"IATA is heavily criticising the European response to the airspace crisis caused by the Icelandic volcano, accusing governments of basing critical decisions on unreliable or incomplete information. ... "Governments have not taken their responsibility to make clear decisions based on facts," says director general Giovanni Bisignani.
"Instead, it has been the air navigation service providers who announced that they would not provide service - and these decisions have been taken without adequately consulting the airlines."
He claims that the "blanket" closure of airspace means a number of airlines have unreasonably been denied opportunities to operate safely.
"This is not an acceptable system particularly when the consequences for safety and the economy are so large," he says. "Risk assessments should be able to help us re-open certain corridors, if not entire airspaces."
European ministers are holding an emergency teleconference today, but this has done little to reassure IATA.
"We are far enough into this crisis to express our dissatisfaction on how governments have managed it - with no risk assessment, no consultation, no coordination, and no leadership," says Bisignani.
IATA last week estimated the daily cost of the shutdown, which began on 15 April, at $200 million.
"In the face of such dire economic consequences, it is incredible that Europe's transport ministers have taken five days to organize a teleconference," says Bisignani.
"Governments must place greater urgency and focus on how and when we can safely re-open Europe's skies. This means decisions based on risk-management, facts and utilising operational procedures that maintain safety."
Jet aircraft were routinely flown into dust laden mushroom clouds a few minutes after 1950s nuclear weapons tests to collect "cloud samples" of fission products. This is important because it is easy to determine the airborne dust concentration from the specific radioactivity of fallout (the amount of radioactivity per gram at 1 hour after detonation); the total lofted dust in grams is simply equal to the total radioactivity produced in the bomb, divided into the specific activity. For decades this data was secret, but after the "nuclear winter" controversy in 1983, Dr Edward Teller managed to get a small amount of data declassified and released in a report by R. G. Gutmacher and others, Total Mass and Concentration of Particles in Dust Clouds, UCRL-14397 (revision 2) which showed that the 110 kiloton 1954 Castle-Koon surface burst at Bikini Atoll produced 500 tons of fallout per kiloton (this production ratio was much less for megaton bombs, because the lofted mass is a constant fraction of the cratered material, and crater volumes scale up less than linearly with increasing total explosive energy). By dividing this total measured dust cloud mass into the total visible volume of the dust cloud, you find the dust concentration in grams per cubic metre. Since many jet aircraft flew through that measured dust loading for known periods of time without suffering damage during nuclear tests, it sets an effective safe threshold.
Because of the similarity, natural volcanic ash has also been used to study radioactive fallout distributions in nuclear weapons effects research programmes.
Update: the U.K. Met Office has shown concern a third of a milligram of volcanic dust per cubic metre of air, detected over Scotland on 19 April 2010: "While the amount sounds small, a typical jet engine would ingest some 60 billion of these particles every second."