University of Iowa Associate Professor of Spanish Denise Filios and her husband, UI English Professor Jon Wilcox, were supposed to fly home late last week from London. But instead, they won’t leave London until at least Thursday.

They hope.

Filios and Wilcox are among the thousands of passengers stranded at airports throughout Northern Europe as a cloud of ash from the Eyjafjallajokull volcano in Iceland spread across the region.

“There are lots of people cramming in [airport hotels], and [there are] some tensions from that,” Wilcox said in an e-mail about the situation in London.

The volcano began erupting on April 14, leaving much of Europe under a cloud of ash. The Associated Press reports officials canceled almost 100,000 flights because of the ash, which can clog jet engines.

On Tuesday, the news agency reported some flights to and from Europe had resumed, but air travel is still inconsistent at best.

Since Monday, Wilcox and Filios have hotel hopped near London’s Heathrow airport, on standby for news of a flight home. They have also had to attend to business they’re missing in Iowa City.

Both were planning to sit on dissertation defenses this week. Filios participated in a defense via Skype on Monday — the connection crashed three times, she said — and Wilcox was able to reschedule his student’s defense for next week.

“Assuming we get back by then,” he said.

Wilcox and Filios are on leave this semester, and they had traveled to the UK to do research at the British Library. The couple used their weekend in airline limbo to visit a castle in southeastern England where William the Conqueror landed his troops in 1066 — a place Wilcox has taught about but never seen.

“Lest you think that medievalists stranded in England take a break from research,” Filios said in a separate e-mail.

Students studying abroad are also among those stranded.

UI junior Molly Slager had been studying in Italy for three months and was scheduled to fly back to the United States earlier this week. Instead, her flights were canceled.

Slager said she rescheduled her flights, but she expects those might be canceled or delayed as well.

“There’s just a lot of people with suitcases sitting around at the train stations,” Slager said in an e-mail. “I have been avoiding the airport, because there’s nothing they can do for me at the moment.”

While the ash still disrupts air travel in much of the continent, there’s a risk of new ash clouds forming from even more violent eruptions in Iceland.

Scientists worry Katla volcano — located around 12 miles from Eyjafjallajokull — could erupt, further hamstringing European travels, the Associated Press reported Tuesday.

That news has another UI faculty member anxious.

UI law Professor Adrien Wing, currently serving as director of the London Law Consortium, is scheduled to fly back to the United States on April 29. Two weeks later, she will have to fly to Arcachon, France, to run the UI College of Law’s summer program there.

“What to do if I can’t get there on time and some students can?” Wing said in an e-mail. “What to do if students trickle in over a number of days as they miss a course with an instructor who can’t stick around?”

Filios said the last few days have made her reflect on the transatlantic travel that she has taken for granted throughout her career as an academic.

“To some extent, I appreciate being reminded so forcefully of the limits of humanity’s conquest of nature,” she said. “It is not ruled by human agency.”

DI reporter Brittany Bierle contributed to this report.