Sunday, April 18, 2010

Thoughts on Europe's volcanic ash cloud crisis and aviation logistics

by B. N. Sullivan

volcanoFor days we all have been watching a crisis unfold in Europe as a large cloud of ash from the eruption of Iceland's Eyjafjallajökull volcano spread over much of the continent's airspace. Because of the presence of ash in the atmosphere at commercial flight levels, IFR air traffic has been suspended or severely limited in most of western and central Europe, save for Portugal, Spain, southern Italy and Greece. This has caused an unprecedented disruption of passenger and freight traffic into and out of Europe, and within the continent. In fact, it seems that the whole world has been affected, since airlines on every continent have had to cancel flights to and from Europe.

Air carriers are losing millions and millions in revenue each day. Faced with the prospect of huge operating losses of a magnitude that threatens their very survival, many in the aviation community are questioning whether this near-total suspension of air traffic in the region really is necessary. In principle, everyone subscribes to the "safety first" mantra, yet many have wondered if what amounts to a continent-wide ground stop is the correct solution. Airline managers and crews alike have begun to debate how to assess the true level of risk at a given time on a given route so that flying can resume.

As of this writing, the volcano is still erupting, it is still spewing a dense column of ash into the air, most of European airspace is still closed, and the outlook is, well, "iffy." There is even a concern that the eruption of Eyjafjallajökull could trigger that of a second Icelandic volcano, called Katla. All three past recorded eruptions of Eyjafjallajökull have triggered subsequent Katla eruptions. If that occurs this time, the present situation certainly could worsen.

In the past 24 hours, several carriers received permission to operate ferry flights to reposition aircraft -- mostly at low flight levels under VFR -- and several of those have been billed as "test flights." Publicity about the outcome of the so-called "test flights" has said that no problems were encountered, i.e., the engines did not choke or become damaged by ash.

The implied message is that since everything was hunky-dory on those "test flights," flight restrictions should be lifted to allow carriers to fly their planes at their discretion.

However, these were not scientifically conducted "test flights." The aircraft were not equipped with particle collectors or other sensors that could detect and measure the composition of the ash cloud through which they presumably flew. The fact that they flew and landed again without apparent problem does not mean that safe conditions prevail.

In contrast, the UK's Natural Environment Research Council (Nerc) did send aloft an aircraft equipped with instruments that could sense and measure components of the ash plume. The aircraft, a Dornier 228, departed from Cranfield and flew over East Anglia and the North Sea, and towards the Dutch coastline. The Nerc researchers reported that their instruments "identified three distinct layers of volcanic residue." Specifically, "Heavy, gritty particles seem to be sitting at around 8,000 feet, whilst lower down in the atmosphere there are sulphurous chemicals and finer dust particles."

The report went on to say, "The Dornier is also fitted with a storm scope and a weather radar, which are standard instruments in any commercial planes, and these were not able to detect the volcanic clouds."

So, is it safe to fly commercial aircraft in the area of the ash plume or not? On the one hand we have a small amount of research data from the Nerc Dornier flight, which documented levels of contaminants in the air column that could prove problematic for aircraft engines. On the other hand, the successful ferry flights provide anecdotal information that at least some flights can be operated safely (although the potential for cumulative effects from repeated exposure to the volcanic ash is not addressed by such flights).

Each of these -- the research flight and the ferry flights -- provided a snapshot of conditions in a particular chunk of airspace at a particular point in time. Unfortunately, neither can logically be generalized to apply to the whole region over a longer period.

Why? Because the location and composition of the volcanic ash cloud is constantly changing, and those changes are difficult to predict with any certainty.

I happen to know a thing or two about volcanic emissions -- not because I am an earth scientist or volcanologist, but because I am a long-time resident of Hawaii's Big Island, where Kilauea volcano has been erupting continuously since 1983. Over the years, those of us who occupy the same island as Kilauea have acquired quite a bit of empirical knowledge about the volcano and its emissions.

Here are a few things I have learned, that also apply to the present situation:
  • Volcanoes do not erupt in a continuous and uniform fashion, but in irregular bursts of varying duration. During some periods a volcano may emit large amounts of ash, smoke, steam, and gases, but those periods will be interspersed with others during which emissions are more sparse.
  • The gunk emitted by a volcano is not homogenized; it varies in composition and density -- sometimes from one hour to the next -- and as the plume rises into the atmosphere and is carried along by winds, some components may become more concentrated, while others may diffuse, or dissipate into the upper atmosphere, or fall to earth.
  • Weather affects the direction and density of volcanic ash plumes. Changes in wind strength and direction, humidity levels, and barometric pressure determine how high a plume will rise, how far it will spread, and how long it will remain in a given area.
And no matter how much you may yearn to be able to just 'put a cork in it' and make it stop, there is no way to control or predict when a volcano will erupt, how long it will continue to erupt, or what kinds and amounts of stuff it will puke up. Its most prominent characteristic is that it is always changing.

The current eruption of Eyjafjallajökull volcano may continue apace, may settle down a bit, or it may intensify. It may cease tomorrow, it may continue erupting for weeks or months, or -- like Kilauea -- for years or decades. And it may or may not trigger that nearby volcano, Katla, to erupt. We don't know, and we can't know.

That said, I really would like to see less debate about whether or not a given sector of airspace is "safe" for commercial air traffic, and instead see more discussion about practical work-arounds. It may be a matter of re-ordered logistics.

If, for example, airports in southern Europe remain largely unaffected, why not engage in an operation not unlike the Berlin airlift, wherein air traffic from abroad is directed in a concentrated fashion to, say, Madrid, Lisbon, and Rome, coupled with a massive mobilization of ground transportation -- buses, trucks, rail -- organized and marketed as a "package" to deliver goods and people to and from cities elsewhere on the continent. And, should changing weather patterns bring the cloud south, contingency plans should be in place to shift traffic to/from other hubs.

I'm sure there are other possible solutions as well, including ramped up sea lift, but the point is that this situation may be with us for some time, and it could intensify. Even if it goes away soon, it could re-occur. Contingency plans must be made to anticipate and deal with events like this, preferably before they arise and devolve into crises.