On April 19th, 2010, IATA, the chief trade group representing airlines, issued a press release which states in part: “IATA criticized Europe’s unique methodology of closing airspace based on theoretical modeling of the ash cloud. ‘This means that governments have not taken their responsibility to make clear decisions based on facts …’ said [Giovanni] Bisignani [IATA’s Director General and CEO].”
This statement leaves the unfortunate impression that decisions based on theoretical models are somehow suspect and of little value. The better, but less soundbite-friendly, question should have been whether the model adequately predicts the risk. To make useful predictions, a model needs to do two things:
- account for all key factors that influence the outcome
- quantify how each factor influences the outcome.
To the frustration of passengers, airlines and businesses around the world, the eruption of the Eyjafjallajokull volcano in Iceland presented several challenges for modelers. Some of the key factors playing a role here include:
- Ash composition: how damaging is it?
- Extent of the cloud: how high, how far and where?
- Aircraft capability: how much ash exposure can airplanes handle?
- The costs of staying grounded vs. the costs of catastrophic failure
These four bullets of course represent just the tip of the ice berg: each of them summarizes a long list of related factors. For example, while current data is unavailable, scientists have to rely on past experience when estimating the size and weight of ash particles, their chemical make-up and the density of the ash. To confound matters, predictions regarding wind speed, direction and turbulence need to be considered as well.
So the real question needs to be: how well does the model represent the current situation? How well do we understand what the actual key factors are? How well can we measure them? Are we relying purely on past insight or can we refine our knowledge with data from the current situation? To what extent can current satellite images, air samples and meteorological measurements improve our ability to predict the risk to life and well-being of people and property?
This interactive map on the BBC we site shows one example of how output from such modeling looks by mapping the extent of the plume over several days along with normal flight routes across the Atlantic. This post in Business Week sheds some light on our spotty knowledge regarding the real risks of volcanic ash.
The other critical question revolves around acceptable risk. Risk not only originates from ash clouds. It also comes from “playing it safe.” Billions of dollars in lost revenues and productivity put the livelihood of hundreds of thousands of people at risk. Every day we accept the risks of driving our car – so at what point do ash clouds represent a higher risk than driving a car? Even if we could come up with an exact numeric value for these risks, how does the value of human life fit into these equations?
Therein lies the apparent disconnect between statistical models and real life: intangible values sometimes outweigh what can be measured. The decisions we make depend on how we actually perceive the risk. Yet, in order to put our perceptions into perspective, we need to have good numbers to guide us – and getting good numbers requires a good model of reality.
So, before we start talking about law suits, we need to accept that risk is inherent to anything we do. Blaming people for doing the best they can to balance public safety with economic considerations wastes resources that would be better spent on improving our ability to assess and manage risks. We send unmanned drones to gather combat intelligence, why not modify them to collect air samples? Why not fund research to create better models for volcanic plumes? Especially if history should repeat itself and Eyjafjallajokull continues to sputter for the next year or two.
From Eruptions, a blog dedicated to volcanism:
Airlines lobby to reopen European airspace closed by Eyjafjallajökull
Posted on: April 18, 2010 2:30 PM, by Erik Klemetti
Eyjafjallajökull flight cancellations: How the right decision is being made to look wrong
Posted on: April 22, 2010 9:40 AM, by Erik Klemetti
Research Gap Left Airlines Exposed to Volcano’s Blast (Update1)
April 22, 2010, 9:05 AM EDT
Is driving more dangerous than flying through ash?
Page last updated at 10:51 GMT, Wednesday, 21 April 2010 11:51 UK
Could aircraft dodge the volcanic ash cloud?
Page last updated at 14:06 GMT, Tuesday, 20 April 2010 15:06 UK
By Stephen Mulvey
Recriminations erupt in ash-fueled aviation crisis
By Arthur Max, Associated Press Writer
How volcanic ash could ground your next flight
By Larry Dignan | Apr 15, 2010
How Volcanic Ash Can Kill An Airplane
Apr 15, 2010 09:00 AM
Story & pictures of KLM Flight 867
Iceland Volcano Vs Mt. St. Helens And Airspace
Pilot’s discussion forum
Volcanic Ash Contingency Plan
ICAO (International Civil Aviation Organization)