In the ageless contest between man and nature, nature reasserted its primacy for an entire week, crippling air travel around the world and sending shudders through the global economy.
Man is now studying the lessons of the volcanic eruption to see how to, if not tame it, at least live with it.
From science to politics, the cloud of volcanic ash that drifted into the bustling air corridors of Europe revealed the inadequacy of the response system to an unfamiliar disaster. It is leading to a thorough post-mortem of an event that scientists say could recur any time — and perhaps with even greater severity.
Civil authorities reacted with extreme caution immediately after the April 14 explosion of Eyjafjallajokull (pronounced ay-yah-FYAH-lah-yer-kuhl) volcano, imposing a blanket no-fly ban in skies stretching from Scotland to Hungary. More than 100,000 flights were canceled, affecting some 1.2 million travelers a day.
"The unpreparedness of the whole decision-making chain was evident from the start," said David Henderson, a spokesman for the Association of European Airlines.
Siim Kallas, the European Union transport commissioner, said he will begin working next week with colleagues to lay out a road map for similar events.
The list of questions he faces is long and complex: How to measure the density and trajectory of an ash cloud; how to determine the safety threshold for each kind of engine; how to weigh the potential economic fallout against the potential danger; how to balance passengers' rights against the industry's health; how to coordinate the response to a crisis?
Some answers almost certainly will compromise the jealously guarded sovereignty with which each nation has protected its air space, even as it relinquished an ever increasing share of control on the ground to the bureaucracy in Brussels.
Kallas said Friday he will present preliminary thoughts to the EU's executive next Tuesday. Among them, he will propose speeding up the plan to unify control over all European skyways.
"The absence of a single European regulator for air traffic control made it very difficult to respond to this crisis," he told reporters. "We needed a fast, coordinated European response to a crisis. Instead, we had a fragmented patchwork of 27 national air spaces. ... We need a single European regulator for a single European sky."
A seamless EU air navigation system would straighten out Europe's zigzag air routes to reduce fuel and congestion in the sky that now keeps planes circling in a landing queue. It also would beef up the role of the European Air Safety Agency that now deals largely with planes' airworthiness, and would enable a single command center to divert traffic and to provide detailed data to national air traffic centers.
The EU had planned to start putting the Single European Sky reforms into effect in 2012, but Kallas said the latest crisis showed "we cannot afford to wait that long."
It's unclear if the reform would have led to a different response than the nervous reaction by the national civil aviation bodies that went along with the blanket closure, at least with the knowledge currently available.
Travel services and import-exporters will study the lessons of improvisation. In the week when most European passenger and cargo terminals were closed, businesses like DHL, the delivery service, engaged in creative routing to move essentials through the few open airports, mostly in Spain, and from there by truck. It's likely that more companies will look into emergency alternatives, including rail and refrigerated shipping for perishables.
Scientists and flight engineers, who still are unsure what is safe and what isn't, will be studying the effects of flying through volcanic debris, which can vary in concentration, chemical makeup and toxicity.
There is an urgency in the work to be done. Eyjafjallajokull has a history of lengthy eruptions, alternately sputtering with lava and exploding with ash for months at a time. And geologists are expecting an even more powerful volcano, Katla, to become active. The last time it erupted, in 1918, men were still flying biplanes.
For politicians and regulators, the debate has just begun over what can be learned.
Aviation executives denounced the lockdown in the sky as a knee-jerk overreaction, but authorities defended their action as prudent.
"It may be too early for us to provide a full list of lessons learned, except that the safety-first precautionary principle must be applied in any future similar situation," said Philip von Schoppenthau, secretary-general of the European Cockpit Association, which represents 38,200 pilots from 36 nations.
Initial calculations put airline losses from canceled flights at around $2 billion, but that is only the beginning of the red ink, Missed flights must be refunded, hotels and meals paid for, flights rebooked. That is EU law, Kallas said. "This is not a voluntary scheme."
But airlines said those rules should be reviewed for extreme cases. "We have also learned that European passenger rights rules simply do not seem to work in conditions like this," said Henderson. Unless they are amended, he said, airlines can keep paying "until they run out of cash."
The airlines say they should be entitled to government support, just like the U.S. government granted $5 billion in subsidies to the airlines after their fleets were grounding by the Sept. 11, 2001, terrorist attacks.
As for travelers, some will take away personal lessons from the ordeal, perhaps rethinking their dependency on air travel in a world where hopping a flight was once second nature.
The crisis only highlighted the shortcomings of airplanes as opposed to, say, trains: lengthy and intrusive security checks, shrinking leg room on board, deliberate overbooking and mounting hidden costs like paying extra for food or drink, a second suitcase and even hand luggage.
For a natural calamity of this scale, it is remarkable that no one was harmed.
In fact, no plane has ever been brought down by volcanic ash. The closest to a disaster came in 1989 when a KLM Boeing 747 flew through an ash cloud over Alaska. All four engines failed and the plane dropped more than two miles in five minutes. The pilots reignited the engines with about one minute left before crashing.
That event taught pilots to act counterintuitively: not to add thrust to a dying engine, which only heats the ash quicker and clogs up the rotors faster.
But there may be no escape from some disasters.
In 1783, another volcano in Iceland, Laki, pumped 120 million tons of sulfur dioxide into the air in an eruption that lasted off and on for eight months. The thick and poisonous haze over Europe literally suffocated thousands of people to death.
Arthur Max reported from Amsterdam. Slobodan Lekic is an AP aviation writer.