April 2010 Archives

The problems with decisionmaking about whether to fly - or not - in the volcanic-ash-affected skies over Europe is that so little is known about these circumstances. The situation is unique in that this ash cloud is affecting a large area of intense aviation activity.

The Met Office weather research Dornier 228 at work

Vocanoes somewhere on the planet erupt frequently, but normally the ash they produce affects areas in which aviation activity is far less intense. The tactic for dealing with ash clouds, until now, has been to fly around them. We never needed to understand them, just avoid them.

Engine manufacturer Rolls-Royce has, today, absolutely refused to comment or to answer questions about anything to do with the current volcanic ash threat.

UK air navigation service provider NATS, in contrast, has been immensely helpful, but honestly admits that the biggest problem it has in making decisions about opening or closing airspace is lack of data about the risk associated with these precise circumstances, and the lack of precision reporting about the position of the ash cloud.

NATS quotes its remit - one which all ANSPs are supposed to follow: they are "not to direct flights into a known flight hazard". If they were to do so, their position would be morally and legally parlous. The question is, is this a "known" flight hazard, or just a suspected one?

One of the consequences of applying the traditional technique of ash avoidance until now is that the aviation industry has never had to research the risk of damage, particularly to aero engines, of flight through areas of widely dispersed upper airspace volcanic ash, rather than the volcanic plume itself. 

The industry fully understands the effects of flying through volcano ash plumes downwind of the eruptions. This concentrated ash clogs the hot section and abrades the cold section of turbine engines, stopping them or dramatically reducing available engine power. Engine core repair following this damage is usually unfeasible, making replacement the only option.

But volcanic plumes themselves are easy to avoid. They don't cover a wide area and Satellites can track them accurately. Unfortunately satellites cannot detect the type of widely dispersed very fine ash particles over Europe at present. Their progress is estimated by computer modelling and atmospheric sampling. But the particles remain abrasive to moving parts in engines. 

There are greater and lesser concentrations of particles at different vertical levels, their distribution determined by a combination between the strength of the individual eruption that projected the ash skyward, then by the weather system. Meanwhile below these layers, the dust is constantly drifting down from the upper air to the ground, so no-where is absolutely ash-free. My car, parked outside in SW London, is covered by a thin layer of ash.

It looks as if today's videoconference of European ANSPs, aviation authorities and transport department officials has produced a decision to try to re-start operations in some of Europe tomorrow. The main reason appears to be a weakening of the volcanic activity - but that weaker level of activity is not guaranteed to be sustained.

Weather patterns, unfortunately, look as if they will sustain a drift of ash from Iceland toward Europe for the next five days at least.

In addition, consideration must have been taken of the results of test flights by aircraft of KLM, Lufthansa, Air France, British Airways and others. Their experience was universally benign. But did they get lucky? We don't know. What's more we don't yet know whether low level abrasion has affected the efficiency of the engines. An increase in fuel consumption for the life of an engine would be a high price to pay for an early return to the skies.

A fully-instrumented Met Office Dornier 228 returned from its flight yesterday saying it had found levels of ash that would probably represent a risk to flight safety.

The Met Office Dornier 228

And on 15 April a pair of Finnish Air Force Boeing F-18 Hornet fighters took off and had serious problems with their engines. When they returned, the inspected engines showed classic internal volcanic ash damage and they may never power an aeroplane again.

Finally, it is not just the Icelandic volcano that has provided Europe with this problem, it is the combination of the volcano and an untypical weather system for the time of year over the British Isles and northern Europe. High pressure and northerly winds have dominated for more than two weeks now, and look as if they will continue to do so.

If only typical April weather for the region were to return, the normal south-westerlies would bring frontal activity and rain showers, and they would drive the ash cloud north east toward northern Siberia, leaving Europe in the clear. 

It was on 24 June 1982 that the world learned, in dramatic fashion for the first time, precisely what kind of damage tropopausal volcanic ash can do to an aircraft. Since then a network of volcanic ash advisory centres - nine of them worldwide - have been set up to monitor occurrences and track their progress until the clouds dissipate.

A British Airways Boeing 747-200 out of Kuala Lumpur, Malaysia bound for Perth, Australia was flying over Indonesia at night with 262 people on board. Suddenly the slipstream noise was magnified and St Elmo's Fire surrounded the aeroplane with a ghostly glow. Then one by one the engines began to fail, until all four had stopped.

The crew decided to head for Jakarta, the nearest international airport, and declared an emergency. During the glide descent they continually went through the engine relight procedure until, when they had cleared the lower limit of the ash cloud, they had success. All four engines relit, but the crew closed down No 2 because it continually surged. The other engines' performance had been seriously impaired, and the ash had sandblasted the front windscreens so badly the crew could not see through them sufficiently to land the aircraft. The pilots had to cock their heads to the side to look out of the direct vision windows which had been less badly affected.

The aircraft landed safely at Jakarta, but the engines were unrepairable. Capt Eric Moody's crew had earned their money that day.

As more information emerges about the accident flight, it becomes increasingly difficult to understand the justification for its planning and execution in the marginal weather that prevailed.

On 10 April the Polish air force Tupolev Tu154M operating the presidential flight took off from Warsaw for the 800km journey to Smolensk Severny (Smolensk North). The latter is a former air force base, recently decommissioned by the military but now used as Smolensk's sole civil/military airport since the recent closure of nearby Smolensk Yuzhny (Smolensk South).

Smolensk airport has no precision approach aids, and meteorological observations provided there do not meet ICAO specifications. For example they can provide estimated visibility from the control tower, but not runway visual range. There were no special arrangements made for the presidential flight, according to our sources. Three days earlier (7 April) the same aircraft had flown the identical trip carrying the Polish Prime Minster, so the crew of the presidential flght should not have faced any unknowns.

The presidential flight was to be carried out in daylight, but fog was forecast at the destination airport. About 90min before the Tu-154 was due to arrive, a Polish air force Special Air Transport Wing Yakovlev Yak-40 carrying journalists landed at Smolensk in fog. About 30min before the presidential flight was expected, a Russian air force Ilyushin IL-96, bound for Smolensk carrying Russian Federal Security Service staff, was ordered to divert because the weather was below minimums. In Russia, air traffic control can give orders to military flights, but both the Polish air force flights had civilian status, so they could only be provided with advice and information.

When an aircraft hits the ground on the approach, it is self-evident that it was lower than it should have been at that point. The answer sought in all approach accidents is why it was too low. The Russian authorities say conversation between the crew and ATC was normal, and the pilots did not report any technical problems. Initial scans of information from flight recorders also suggests no problems with the aircraft.

If that is the whole truth, we are in the familiar realms of human factors.

If a pilot is determined to land from an approach in marginal conditions, it is tempting for him/her to continue descent below the minimum descent height (MDH)  for the approach aid in use, hoping to see the runway through the fog, and relying on seeing the ground below the aircraft so as to avoid collision with it. In the case of the presidential flight, according to air transport regulator Rosaviatsia's chief, Alexander Neradko, the aircraft was so low that it hit an 8m high tree when still 1,200m from the runway threshold. At that point on a standard 3deg approach glideslope it should still have been at 60m height, says Neradko.

But whatever the height of a theoretical glideslope at 1,200m, this flight should not have descended even as low as 60m (182ft) on this approach without the pilots being able to see the runway - and with the reported visibility being 400-600m in fog, they could not have done. The airport has no precision approach aids, and the status of the aids it has have not been confirmed by the authorities yet.

So why would pilots have ignored their minima? Widespread press speculation suggests pressure from the senior military personnel on board influenced the captain, but it's not at all clear how they could know that. Pilots flying their country's president would not need external pressure to feel the need to land successfully - they would supply their own. The only safeguard would have been the discipline needed to stick to the rules and disappoint nearly 100 of Poland's top officials by insisting on diverting a long distance away from Smolensk, and thus from Katyn, where the President was due to lead his retinue in honouring the memory of Polish soldiers who died in a Second World War massacre 70 years ago. 

When it closed as a military base in October 2009, Smolensk Severny had surveillance radar and a Russian RSPB beacon, almost identical to the western military aid TACAN (tactical air navigation), which operates in an overlapping frequency band. RSPB, like the civilian VOR/DME, offers bearing and range from the beacon, but slightly more accurately than its civil counterpart. It is still, however, not a precision approach aid. The status of the RSPB and the airport surveillance radar on that day is not known at present, but if surveillance radar were available the crew could have been provided with non-precision lateral and range guidance on the approach to the runway, which in this case was runway 26. Reports suggest that ATC was providing vectoring guidance, but what kind is not clear.

As a final caveat, it has not yet been possible to check some of this information with official organisations, so any input from industry professionals is welcome.

Following the world's first court verdict establishing the previously missing legal acceptance that there is a connection between contaminated cabin air and crew/passenger health, it's a good time to examine the law and politics behind the courtroom arguments.

We'll start with a comparable set of legal circumstances in another industry: tobacco.

This comparison is useful only as a study of the way society processes the discovery of health risks.

The tobacco industry has been through the whole process which, in the case of toxic fumes in aircraft cabins, the air transport industry is just beginning to face up to. The process of facing up to the risk is likely to follow a remarkably similar path.

The tobacco industry did not set out to provide people with carcinogens, and aircraft/engine manufacturers did not set out to allow neurotoxins into aircraft cabins, but in both cases, as a secondary effect of providing their primary products, a risk exists.

In 1954 the American Cancer Society said this: "The evidence to date justifies suspicion that cigarette smoking does, to a degree as yet undetermined, increase the likelihood of developing cancer of the lung."

Societal attitudes forty or so years ago are illustrated by the fact that, in 1965, as an officer cadet in the UK Royal Navy, I was provided at incredibly low cost with a ration of 200 cigarettes a month. I was not compelled to accept the ration, but I smoked them anyway.

It was about that time that court cases alleging tobacco companies' responsibility for causing lung cancer were becoming big news. But the rearguard legal defence action by companies like American Tobacco lasted years, the chief weapon being the argument that lung cancer can have many different causes, and that the connection between smoking and lung cancer could not be proven.  

Eventually it was proven. Today many people still choose to smoke, but the major difference is that everyone who does so is made aware of the risk.

I'd better make it clear at this stage that, although there are process parallels between dealing with the tobacco smoke/lung cancer issue, and the potential for passenger and crew harm through organophosphate fumes in cabin air, there are differences too. Most flights are fume-free, whereas every cigarette smoked exposes the smoker's lungs to carcinogens.

The comparative downside is that many crew and almost all passengers have no knowledge of the fact that they could, during any flight in an aircraft with cabin air supplied from engine or auxiliary power unit compressor bleeds, be exposed to neurotoxic organophosphates.

But what if they are? Symptoms are obviously affected by the dose, but in an intense fume event some people could be badly affected for the rest of their lives, and others get away with it entirely. Individual susceptibilities vary. The trouble is, you won't know whether you are susceptible or not until you are exposed to it. If you want to know more, visit the Aerotoxic Association's website.

 The effect on the human nervous system of certain organophosphates has been known for many years. So, for non-lawyers, making a connection between the presence of toxic fumes in an aircraft cabin and potential harm to the health of those in the aeroplane does not take much intellectual effort. It's obvious. But lawyers are paid not to see it that way.

If the air transport industry wants to buy itself time before it has to do something about aerotoxic syndrome - and it does want to buy time - its lawyers are given the job of making it as difficult as possible to prove a connection between a fume event and a case of illness in a passenger or crewmember. The burden of proof is on the plaintiff. There is no requirement for the airline or the manufacturer to prove anything, so all they do is work to discredit the evidence provided by the plaintiff. If that doesn't work, they employ legal technicalities. The process is nothing to do with justice.

Meanwhile, more difficult to understand is the attitude of the authorities. In the case of the UK, for example, that would be the Department for Transport and the Civil Aviation Authority. You would have thought that their job would include protecting the health and safety of passengers and crew. Apparently they don't think it is. They, like the lawyers, are waiting for proof on their terms. The amount of evidence that they have decided not even to consider is massive.

Government organisations like the Committee on Toxicity will not accept evidence gathered by organisations like the Aerotoxic Association or the Global Cabin Air Quality Executive on the grounds that they are interest groups. Implicit in that decision is the COT's judgement that the industry itself is not an interest group! 

Then there is the absolutely unbelievable case of pilot unions like the US ALPA, the UK BALPA, and organisations the European Cockpit Association and IFALPA. They are happy to go along with this dissembling rather than fighting to protect the health of their members. Strange.

But the tobacco industry eventually had to accept reality, and whatever you may think of it, it is prospering despite accepting reality. The aviation industry could do the same. There is hope yet, especially following the 1 April New South Wales Court of Appeal decision.