Why not ALL flights cancelled due to Ash

[Sigene]

This article on CNN Volcano's grip on Europe's airspace expected for 3rd straight day - CNN.com) implies that SOME flights are occuring including a few transatlantic flights. I don’t understand why all of them are not cancelled. Either its too dangerous to fly or it isn’t.

Can someone enlighten me as to how some flights are deemed safe, when the majority are cancelled.

[Duckster]

Upper air space has been made available in some of these restricted areas, depending on the observed and forecasted area of ash contamination, air traffic officials said. Parts of southern Europe, including Spain, the southern Balkan area, southern Italy, Bulgaria, Greece and Turkey remained open and flights were taking place in these areas, the officials said.

The ash is not covering all of Europe, … yet.

[Martini_Enfield]

@Duckster

The ash is not covering all of Europe, … yet.

Spain, for example, is unaffected. The BBC was reporting there’s a plan afoot to fly stranded Britons to Spain from wherever they are (outside Europe, obviously) and then take them home via ferry from Santander or somewhere like that.

[Cardinal]

Britain is sending navy ships to get people across the channel, as I guess there are too many for the Chunnel trains.

[wmfellows]

@Sigene

This article on CNN Volcano's grip on Europe's airspace expected for 3rd straight day - CNN.com) implies that SOME flights are occuring including a few transatlantic flights. I don’t understand why all of them are not cancelled. Either its too dangerous to fly or it isn’t.

Can someone enlighten me as to how some flights are deemed safe, when the majority are cancelled.

Flights going to open airports.

Of which you have Iberia - Spain and Portugal (although the Northern airports closes this weekend in Spain), Italy, at least mid to South, Greece, Turkey.

[Magiver]

Adding to the problem is the difficulty identifying what altitude the ash is at. If it doesn’t pick up moisture then it won’t return a radar signature.

[JoelUpchurch]

NY Times Article

Authorities Criticized Over Handling of Flight Ban

Vienna airport has reopened.
Airports in the Czech Republic have reopened.
Flights over Scotland will resume tomorrow

Lufthansa has also been allowed to make a “very small number” of flights from Germany to the United States and destinations within Europe starting at 6 p.m. local time Monday, said Amelie Schwierholz, an airline spokeswoman. The planes will have to fly through specific corridors at lower elevations of 10,000 to 23,000 feet, she said.

Aviation authorities in Hungary announced they had reopened the country’s airspace for aircraft flying at 24,600 feet or higher.

Most airlines can fly above the ash cloud. The risks that need to be accessed is during ascent to cruising altitude.

[wmfellows]

@Magiver

Adding to the problem is the difficulty identifying what altitude the ash is at. If it doesn’t pick up moisture then it won’t return a radar signature.

Quite right and that element of uncertainty is the nasty item, as the risks of having a 747 or the like suddenly experience what the BA flight in Indonesia did (four engine failure, massive windscreen damage) over populated terrain is not a pleasant risk to assume.

[Sailboat]

To paraphrase Frank Zappa:

Some flights don’t go where the ash clouds go – and Lord, don’t eat Icelandic snow.