London's Heathrow airport, one of the world's busiest travel hubs, has re-opened for landings after a six-day air travel freeze across most of Europe that grounded some 95,000 flights.

European authorities say many more airports across the continent are set to reopen on Wednesday.

But the ash clouds are still visible and shows no sign of letting up as wind currents move it across the UK. Technical experts say it still represents a real danger to aircraft in the sky.

For now, though, airlines are celebrating a breakthrough allowing them to bring passengers home and stem losses which could top $1bn.

Al Jazeera's Imran Khan reports from Heathrow airport in London.