- Volcanic ash cloud
- Met Office
- Air travel
- Cancelled flights
Or was it? According to the latest evidence, the notorious cloud was virtually non-existent and, where it was present, was so thin that it posed no threat.
The news will leave out of pocket tourists and airlines alike fuming over the six days of anguish and travel nightmares.
Satellite images showed that the skies above Britain were largely free of dust danger and Jim McKenna, head of airworthiness at the Civil Aviation Authority, confirmed to the Daily Mail: "It's obvious that at the start of this crisis there was a lack of definitive data.
"It's also true that for some of the time, the density of ash above the UK was close to undetectable."
But the news will mean that the airlines, already insisting that the Government compensate them for the tens of millions lost to the six day flight ban, have an even stronger case.
The decision to clear British airspace was taken in view of Met Office computer models which appeared to show a cloud of ash billowing southwards from the Eyjafjallajokull volcano in Iceland.
However, they weren't tested by the Met Office's main research plane, which was holed up in a hangar awaiting a paint job until Tuesday - by which time the ban was drawing to its conclusion.
In fact, the evidence suggests that the maximum density of the ash was just one 20th of the "safe" limit agreed upon by scientists, the Government, and aircraft manufacturers.
So how could the Met Office get it so wrong and why was the Government so quick to ban air travel?