Atmospheric volcanic ash in serious quantities is new to Europe, and the learning curve on how to deal with it is steep. But it needs to get steeper, because it seems the number of differences in the way national aviation authorities are interpreting the internationally agreed guidelines almost equals the number of authorities in the Eurocontrol countries.
An example is last week's UK Civil Aviation Authority decision to dispense with the 60nm (111km) safety buffer zone around the estimated position of the ash cloud. At the same time the European Aviation Safety Agency was continuing to refer to the need for a 120nm buffer. Also lacking is Europe-wide agreement on how to measure, and react to, the acceptable ash contamination density. Europe may have unified agencies like EASA, Eurocontrol and the European Civil Aviation Conference, but Eyjafjallajökull has scattered national authorities like its ash, revealing how fragmented an aviation entity Europe still is.
The transatlantic picture is similarly confusing. North America has more experience of volcanic ash than Europe does, especially on the more northerly parts of its Pacific rim, but all its worst-affected regions are relatively low-traffic areas where avoidance is almost always possible, and therefore almost always adopted. Alaska Airlines says it will not even taxi its aeroplanes if ash is known to be present.
Europe's ash cloud is uniquely inconvenient because it affects the busiest air traffic region in the world, and it sometimes sits over the top of the continent so avoidance is not an option.
The Alaska volcanic activity advisory centre (VAAC) works on the same International Civil Aviation Organisation terms of reference as the London VAAC does, just as the US Weather Service International uses the same science as the UK Met Office to track weather and thus ash cloud drift. But that, apparently, is where the similarity ends.
Once the atmospheric data has been measured or calculated, how does the local system interpret it? Interpretation seems to be the key to differences.
As already observed, it depends where you are in Europe. Transatlantically, the mathematical models used by the WSI or the Met Office to calculate ash drift are based on the same algorithms, but it seems there is a difference in the assumed starting point.
The Met Office assumes residual ash remains in the atmosphere until it is cleared by factors like gravity or rain, and it measures continuing eruptions to see how much new material is thrown up to supplement the residual ash. The US Federal Aviation Administration's model works mainly on the ash newly emitted by the volcano and takes less account of the residual cloud.
They can't both be right in their approach. But since aircraft have not been falling out of the FAA's skies, maybe Europe had better look at whether the FAA actually has a workable model or has just been getting lucky. After all, the FAA advice to all aircraft is still what it used to be before Europe tweaked the figures in the interest of staying in business: avoid all volcanic ash at all times if humanly possible.
Finally, there is an ash detection technology that could be installed in aircraft to warn pilots of the presence of ash. Dr Fred Prata of the Norwegian Institute for Air Research says passive infra-red detection can "see" fine ash in dispersed quantities. But this is not a commercial, certificated product, and Prata points out that certification for use on aeroplanes "won't happen quickly".
He also picked me up on my statement that weather satellites cannot see dispersed ash, explaining: "Since I am an expert in satellite remote sensing of volcanic ash, I would like to say that we can detect fine ash from satellites and have done so for at least 20 years. Like the models (or anything really) it is not perfect, but actually pretty good."
He says that the airlines are, naturally, asking for a lot: "The industry seems to want 'no-fly zones' determined, and longer-term forecasts for route planning. Fair enough, but given the imperfect nature of the [mathematical] models and the satellite data, I wonder how well this can be done."
Eyjafjallajökull could mess up European aviation for years to come if it continues to erupt, so the agencies had better sort out what best practice is, and what we must research so we can get smarter at mitigating the operational effects of the ash cloud.
on May 17, 2010 8:40 PM | Reply
We are getting there! The panicky reaction has "annoyed" quite a few interested parties and now it’s time to accept that 100% safe transport (ground, sea, air) is utopia and we must accept the necessary minimal risks. Trains, maritime transport, taxies and all ground transport facilities have had their good day. The time has come to accept the American model and carry on with our job, that is air-transport our customers like we’ve always done. Insurance providers, airlines & engine manufacturers must share the risks and costs of their actions.
on May 23, 2010 2:30 PM | Reply
So we are in a brave new world of assumed ash since April 15th 2010. Quite a Titanic date for civil aviation.
And a terrible beauty of Eyjafjallajokull is re-born of Iceland’s fire and ice topography. Being humbled before Vulcan’s throne is sobering and inconvenient, at best. In my case, twice in Ireland from April 15-22 and on May 5-6. In CA crew rosters all volcanic displaced personnel are referenced as E-15 after April 15 2010, a new addition to book keeping. I improvised after being liberated from choice of actionable option and washed down the ash residue with Guinness and Beamish and Guinness again, it worked. Assumption makes an ass of u and me. Or in this case, Ash-umption does… QED. Of course in aviation, assumption-operationally speaking-is generally the mother of disaster. But, we have in fact been using an educated assumption from the Wright brothers to the operation of military and commercial jet aircraft, from 1013hPa in ISA-land, approaching Flight Level-land to CAT I-II-III Decision visual fail-operational Heights to Alert invisible avionic fail-passive heights.
The initial trusted-thrust assumption is a reduced takeoff thrust when noise abatement and runway and weather conditions permit. This assumed temperature is called FLEX, (as we would not like it be known that we assume anything). FLEX is on average 30C above ambient with the maximum thrust reduction being 25% below any authorised rating. The Assumed Temperature method assumes a rated thrust VMCG, so it is not considered a limitation. Therefore if more thrust is desired during takeoff for, lets say, a sudden windshear gust putting the throttles prematurely into the HOLD-dormant mode, below 65 KTs, the Captain has freedom to firewall. If the ambient attained the assumption, “Phew, wot a scorcha !”, then the thrust levers would be at the forward stop to attain the rating or applicable fixed de-rating.
A De-Rate is EICAS annunciated as D-TO-1 or 2 for 10-20% fixed reduction, respectively. If D-TO-2 is selected, climb thrust selection is not required-if one wants to climb at a commercially viable weight. V-speeds are therefore predicated on a lower thrust, resulting in a lower V1 and therefore a shorter runway, so it is considered a limitation. The general benefits are more protection from going off the runway edge, than it’s end. And long term preservation of the engine’s core N2 hot section surge margins and resultant specific fuel consumption margins. So available thrust to take-off and climb at 1.7% 3 out of 4 gradient B-744/A-340 is assumed flexibly against a rating or de-rating. E-15’s multi-FIR shutdown is assumed against no rating of previous zero tolerance. A zero-sum gain in which a regulator wins with public comfort and political vindication and a zero-sum loss in which airline and public passengers lose without comfort. How long is a piece of string ?...Europe’s single sky was indecisive, but in the wake of a theoretical ash cloud it is unsure. A B-744 end of takeoff briefing addendum with a 14C ambient dry temperature would be thus :”Flaps 20, trim set, D-TO-1, FLEX 44 THRust REF SEL, CLimB 1 ARM, L & VNAV armed.” The regulatory brief addendum to parroting Eurocontrol from it’s applicable constituent single sky ATS members was, “We don’t know where we are, so we are going nowhere, as we are all equally ignorant of this known unknown !”
With assumed RESIDUAL ash there is no such solid reasoning and as said , has illustrated a mathematical model that is beginning to make Al Gore sound intelligent and the University of East Anglia’s Climate Research Unit sound credible, this really is an inconvenient truth. This is a real worry, even more than the new religion of environmentalism or mentalism for short. It is actually well en-route to making psychiatry appear scientific, which previously made religion seem so. Residual theoretical ash must not snuff out residual thrust and trust as it has done by acute and obtuse regulatory overreaction since April 15, depending on where the ephemeral Hector O’ Pascal was sitting highest. The time for CAA ash drones has dawned. Their cost can be amortized against the blanket shutdown, very quickly if the April foolishness was any guide.
As David said, the FAA has operated an Icarus-free de-facto Volcanic Ash METAR promulgation service for many years. The London VAAC does Forecasts, based on mathematical models. In other words, static statistics in a dynamic environment. Consider the response of the airframers and powerplanters. They moved the decimal point of ash tolerance to the right, just around the time as Greek Achilles Heel accounting mythology, GDP, translating as Greek Decimal Point, moved left in the face of reality. Without testing, the A&P statistics are more credible as they have operational experience , checks, balances and TBO failure margins. Since E-15 didn’t erupt since 1821, it is understandable that it was never factored into Europe’s dense airspace traffic patterns.
Willie Walsh, former pilot and current BA CEO said on May 21, caught between mounting losses, industrial unrest and a vomiting volcano, that he has “No confidence in VAAC mathematical modeling and it was a gross overreaction for the CAA to shut down UK airspace upon it’s advice of a non-existent ash cloud”. I agree.
So the way forward is ash clear, to wit : EU transport ministers must order VAAC-NATS, EASA, Eurocontrol and the EU to propose formulating and agreeing a joint multi-agency proposition to elicit a UN Security Council resolution condemning unambiguously and without qualification, mitigation or reservation the unprovoked eruption and indiscriminate scattering of ash in European airspace and to desist erupting forthwith or suffer the consequences of-er- another binding resolution, augmented with an EU directive and possibly being taken to the European Court Of Human Rights or International Criminal court in The Hague. This exercise would be 100% more effective than how these institutional agencies of ineptitude have reacted thus far in isolation and combination. I’m convinced the volcano will see sense in the face of such resolute fortitude and stop being such a plane in the ash, as these agencies have been. And it would also be demonstrably the most useful thing the UN has done since the Korean War, perhaps only useful thing. Since the UK embraced a ConDem coalition of Dave and Nick on May 11 the UK is in a brave new political world, not seen since Winston and Clement. This is the frequent result of PR electoral politics, a tentatively optimal result in which everybody gets what nobody wanted for blunting or yawing the extremities of each party to optimal centre line CRM-hopefully. It is ash high time that we also embrace Proportional Regulatory Representation of the facts, not the theory.