While it is still unclear how long flights will be grounded, at least one airline expects it will take at least several days to clear out any backlog. Delta Airlines is letting passengers booked through Sunday to fly in or out of several European airports including London, Amsterdam, Dublin, Paris, and Brussels -- to change their tickets for free.
There have been other incidents of aviation problems and restrictions caused by volcanic eruptions, but "nothing quite as dramatic as this has happened before" said Yates.
"Aircraft have suffered in the past when they've flown into ash, most notably a BA flight in 1982 which lost all four engines."
That British Airways plane was flying over Indonesia to Australia when it passed through a volcanic cloud.
"Anyone who goes into volcanic ash is a nutcase, it's very dangerous material." Eric Moody, the pilot on the 1982 flight, told ABC News today.
Moody was over the Indian Ocean when suddenly all four engines stopped.
"On the flight deck, the three of us, myself, first officer and flight engineer, admitted that when we got on the ground that we were totally confused," Moody said.
Miraculously, Moody managed to restart the engines once he had exited the ash cloud and land the plane safely in Jakarta.
"I will admit to a bit of apprehension just before they started." he said.
He found out two days later that volcanic ash had caused the engine failure.
A similar incident occurred in 1989 when a KLM Royal Dutch Airlines Boeing 747 flew into an ash cloud from Alaska's Redoubt volcano and lost all power, dropping from 25,000 feet to 12,000 feet (7,500 meters to 3,600) before the crew could get the engines restarted. That plane also landed safely.
ABC News' Lama Hasan and The Associated Press contributed to this report.