By Artyom Liss BBC, Domodedovo Airport, Moscow

The flow of air passengers has continued despite the crashes

"I only learned the news when one of the journalists asked me what I think about it all," says Marina, 43, on her way to a resort in Turkey.

"Everybody is so calm and collected here - and this makes you so much more confident about flying."

From a huge video screen above Marina's seat in the waiting hall, a Russian pop star beams down an aura of peace and prosperity.

And just opposite, across the hall, shoppers are browsing in incredibly expensive airport boutiques.

Business as usual indeed - but the tranquillity is deceptive.

Speculation

Just four storeys higher, at Domodedovo's corporate headquarters, dozens of journalists are anxiously marching up and down the long corridors, trying to corner anybody with an airport ID.

There was little sense of disaster having occurred

And rumours are flying.

Did somebody really get on board without going through the check-in procedure?

Did six passengers on one of the flights really vanish into thin air somewhere between the check-in desks and the gate?

And what happened to their luggage? Could it be that the planes were shot down because they got too close to nuclear power stations?

As journalists are taken downstairs, to see how baggage is handled and what security measures are in force in Domodedovo, it becomes obvious that airport officials are unlikely to say anything other than express their condolences to friends and families of the victims.

Terror theories

Just across the road, at the headquarters of the Sibir Airline which operated one of the flights, there is already talk about possible causes of the crash.

You can carry a bomb aboard an aircraft or fly an old machine... it all depends on how much you are prepared to pay Anton Moscow resident

"Just seconds before our liner hit the ground, pilots pressed the hijack alarm button," says Ilya Novokhatsky, Sibir's PR manager.

"And just as the controllers received this May Day message, the airplane went off their radars".

At the Federal Security Service, these reports are "being considered", with the main line of inquiry a "breach of civil aviation regulations".

Security at the airport has already been tightened

But even now, as the investigation into the causes of the crashes is just beginning, many Muscovites are already certain: whatever officials say, the disasters were not an accident.

"Planes don't just explode by themselves in the sky," says Andrey, 25.

"There was a flash and an explosion. So the plane was blown up. That means it was terrorists - and that just gives the Kremlin another excuse for more military action in Chechnya."

Anton, another Muscovite, thinks corruption is at the root of all problems with Russia's airlines.

"Money buys you anything," he says.