Britain Decides It's Safe to Fly: Skies and Airports Reopen

British airports and airspace reopened today for the first time since massive volcanic ash clouds from Iceland grounded hundreds of planes and stranded thousands of passengers nearly a week ago.

A British Airways flight from Vancouver, British Columbia landed at London's Heathrow airport just after 10 p.m. local time, becoming the airlines' first flight to land -- or take off -- from Heathrow since last week.

Britain's Transport Minister Andrew Adonis announced that all U.K. airports will reopen at 10 p.m. (5 p.m. ET). Airports in Britain have stayed closed longer than other European hubs, due to the threat of more ash clouds blowing into British airspace.

VIDEO: The first flights arrive in London since Icelandic volcano grounded planes.Play

Heathrow is Europe's busiest airport, and airlines were eager for it to open its gates. British Airways alone hoped to land as many as 25 international flights in London tonight, including flights from the United States.

Flights resumed across much of northern Europe earlier today. Eurocontrol, Europe's aviation safety organization, said it expected 13,000 flights, about half of the scheduled departures to take off today. Still, some European airspace remains closed to jet traffic. Much of Germany's airspace remain closed until 8 p.m. ET due to a lingering ash threat, though some 800 flights were allowed to fly at low altitude.

"It's difficult to say when we will be back at full capacity," Eurocontrol's deputy head of operations Brian Flynn told "Good Morning America" today. "A good expectation [is] that in about two day's time we would return to very near normal situation."

VIDEO: Icelandic Volcano Loses Its Punch Play

Near the crater of Iceland's Eyjafjallajokull volcano, one of Iceland's top scientists monitoring the eruption said today that the worst is likely over.

"I think it is clear that the activity, the amount of magma that is coming up into the crater is decreasing. It has decreased quite markedly over the last few days," said Magnus Gudmundsson of the University of Iceland.

The volcano in southern Iceland is still spewing smoke and lava, but the ash plume is lower than it previously was, posing less threat to high-flying aircraft. Gudmundsson did note, though, that scientists "cannot be sure" the situation will continue to improve.

Stranded Passengers Cheer Liftoffs

The sound of jets finally taking off was music to the ears of stranded passengers.

VIDEO: Passengers are wary and relieved as some grounded airplanes fly again.Play
Air Travel Resumes Despite Volcanic Ash

"We were in the hotel having breakfast, and we heard an aircraft take off. Everybody got up and applauded," said Bob Basso, 81, of San Diego, who has been staying in a hotel near Charles de Gaulle Airport near Paris since his flight Friday was canceled.

Ash that had drifted over the North Sea from the volcano in southern Iceland was being pushed back over Britain today by shifty north winds, Icelandic scientists told the Associated Press, but Eurocontrol said it coordinated with meteorologists from across the continent to establish safe flying zones.

"It's a matter of wind directions. The volcano's plume is quite low actually, still below 3 kilometers (1.8 miles) near the volcano," said Gudrun Nina Petersen, meteorologist at the Icelandic Met Office.

VIDEO: Grounded FlightsPlay

Ash Plume Is Lower, Easing Threat to High Flying Jets

Earlier today, a Eurocontrol map showing the ash cloud listed the airspace between Iceland and Britain and Ireland as a no-fly zone, along with much of the Baltic Sea and surrounding area. The ash cloud also spread westward from Iceland, toward Greenland and Canada's eastern coastline, but at a less dangerous lower altitude.

"The European Commission has been working day and night to try and be sure that we are able to open the airspace bit by bit and do it in a gradual and a safe way," Flynn said.

European Union officials had been receiving increasing pressure from the aviation industry, which is losing an estimated $200 million in revenue per day due to the grounding.

VIDEO: Iceland Volcano Shuts Down U.K. AirportsPlay
Volcano in Iceland Shuts Down Airports

Officials from across Europe agreed on Monday to create three zones for flying over Europe -- a no-fly zone over the ash cloud, a caution zone in nearby areas "with some contamination," and an open-skies zone. Planes flying in the caution zone will need to be checked for engine damage.

For those passengers lucky enough to be on the first flights out, elation at finally getting in the air was only tempered by a fear of what the ash might do.

"I was very nervous," Lufthansa passenger Dominique Burkhard said of his Los Angeles to Frankfurt, Germany, flight. "One time we had turbulence. This was not so funny."

Britain Suspends 'Titanic' Laws to Help Ferries Carry More, U.S. Offers Emergency Loans

SLIDESHOW: Volcano Flyover: Ash Encounters

While it was still unable to take to the skies, the British government hoped to ease waterborne escapes from the island by suspending the "Titanic Laws," allowing ferries to carry more passengers than would normally be legal.

It's the first time such a measure has been taken since the laws' implementation nearly 90 years ago after the Titanic disaster in 1912. Dozens died after the massive ship's fateful run-in with an iceberg partially because there were far too many passengers for the number of lifeboats on the ship.

For Americans, home is a lot farther than a ferry ride away and the U.S. State Department said it had no plans to evacuate citizens by air or water, noting that by the time an evacuation could be organized, commercial flights would likely be available.

Eurocontrol predicted that by the end of the day, a total of 95,000 flights will have been cancelled since Thursday.

For those who have run out of money while stranded abroad, the State Department said it had a "limited amount of emergency loans that may be made available" under some circumstances and will help people send money to stranded loved ones.

Click here for more information at the State Department Web site.

ABC News' Maeva Bambuck, Bradley Blackburn, Kirit Radia and the Associated Press contributed to this report.