The problems caused by the eruption of the volcano in Iceland have caused an estimated 300,000 flights to be cancelled and almost a billion in economic damage. New York City, alone, has suffered over $250 million in economic damage.
The British Civil Aviation Authority maintains that test flights of planes in low levels of ash were successful. But given the known dangers of such flight attempts, and the varying skills of pilots in what is an unusual situation, it would seem to tempt fate to invite flights while the airspace is far from clear of volcanic ash.
While the British CAA has been accused by some of overreacting to the volcano in Iceland, reopening due to economic and family pressure, not discounting such issues, is dangerous if as it appears, CAA officials aren't clearly sure of the level of safety in the European airspace.
The decision to reopen Heathrow at this time is a risky one. We can only pray to God that it was the right one.